Relevant bibliographies by topics / Cucurbita, chemistry

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers

Academic literature on the topic 'Cucurbita, chemistry'

Author: Grafiati
Published: 4 June 2021
Last updated: 5 February 2022

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Journal articles on the topic "Cucurbita, chemistry"

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Wang, Da-Cheng, Hong-Yu Pan, Xu-Ming Deng, et al. "Cucurbitane and hexanorcucurbitane glycosides from the fruits of Cucurbita pepo cv dayangua." Journal of Asian Natural Products Research 9, no. 6 (2007): 525–29. http://dx.doi.org/10.1080/10286020600782538.

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Li, Yuan, Arend-Jan Both, Christian A. Wyenandt, Edward F. Durner, and Joseph R. Heckman. "Applying Wollastonite to Soil to Adjust pH and Suppress Powdery Mildew on Pumpkin." HortTechnology 29, no. 6 (2019): 811–20. http://dx.doi.org/10.21273/horttech04391-19.

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Although not considered an essential nutrient, silicon (Si) can be beneficial to plants. Si accumulator species such as pumpkin (Cucurbita pepo var. pepo) can absorb Si from soil. Si uptake may reduce plant susceptibility to fungal diseases such as cucurbit powdery mildew (Podosphaera xanthii and Erysiphe cichoracearum). We previously reported that wollastonite, an Organic Materials Reviews Institute–approved natural mineral, can increase soil Si level, increase soil pH, provide pumpkin plants with Si, and increase their resistance to powdery mildew. In this study, we examined the optimum application rate of wollastonite for pumpkins grown in pots and exposed to cucurbit powdery mildew. We confirmed that wollastonite has liming capabilities similar to regular limestone. Regardless of the application rates, wollastonite and limestone showed similar effects on soil chemistry and plant mineral composition. Pumpkin plants grown with the lower doses of wollastonite amendments (3.13 and 6.25 tons/acre) had the greatest tissue Si concentrations and demonstrated the greatest disease resistance. We conclude that wollastonite is a useful material for organic cucurbit (Cucurbitaceae) growers who want to increase soil pH and improve plant resistance to powdery mildew at the same time. Applying wollastonite at rates beyond the amount required to achieve a desirable soil pH for pumpkin production did not further increase Si uptake, nor did it further suppress powdery mildew development.
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Kulczyński, Bartosz, and Anna Gramza-Michałowska. "The Profile of Secondary Metabolites and Other Bioactive Compounds in Cucurbita pepo L. and Cucurbita moschata Pumpkin Cultivars." Molecules 24, no. 16 (2019): 2945. http://dx.doi.org/10.3390/molecules24162945.

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Plants and animals are sources of various bioactive compounds that exhibit a broad spectrum of health-promoting effects. Scientists continue studies on the chemical composition of many products in search of foods with high nutritional value. The pumpkin (Cucurbita sp.) is unquestionably a source of valuable nutrients. This vegetable is well-known all over the world and it is appreciated due to its high content of carotenoids, but it is still not much used in the processing industry. The aim of present study was to compare the flesh of 15 pumpkin varieties belonging to the Cucurbita pepo and C. moschata species in terms of the bioactive compound content (carotenoids, phenolic acids, flavonols, minerals and vitamins) and to demonstrate whether the variety has an effect on the chemical composition. To date, no such extensive research has been carried out in this area. The research revealed that the pumpkin pulp had high content of carotenoids. In nearly all cases lutein was the most abundant carotenoid. Numerous phenolic acids and flavonols were also identified. All the cultivars contained gallic acid, protocatechuic acid, 4-hydroxybenzoic acid, vanillic acid, chlorogenic acid, caffeic acid, and rutin. The pumpkin pulp also contained alpha- and gamma-tocopherol. No beta- or delta-tocopherol was found. Potassium, calcium, and sodium were the most abundant minerals. The research also proved that the profile of bioactive compounds in the pumpkin pulp was considerably diversified and depended on the species and cultivar
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Kulczyński, Bartosz, Andrzej Sidor, and Anna Gramza-Michałowska. "Antioxidant potential of phytochemicals in pumpkin varieties belonging to Cucurbita moschata and Cucurbita pepo species." CyTA - Journal of Food 18, no. 1 (2020): 472–84. http://dx.doi.org/10.1080/19476337.2020.1778092.

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Ara, Neelam, Korakot Nakkanong, Wenhui Lv, Jinghua Yang, Zhongyuan Hu, and Mingfang Zhang. "Antioxidant Enzymatic Activities and Gene Expression Associated with Heat Tolerance in the Stems and Roots of Two Cucurbit Species (“Cucurbita maxima” and “Cucurbita moschata”) and Their Interspecific Inbred Line “Maxchata”." International Journal of Molecular Sciences 14, no. 12 (2013): 24008–28. http://dx.doi.org/10.3390/ijms141224008.

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Henderson, Curtis W., Joseph C. Scheerens, and James W. Berry. "Antinutritional factors in Cucurbita seed meals." Journal of Agricultural and Food Chemistry 34, no. 3 (1986): 434–36. http://dx.doi.org/10.1021/jf00069a013.

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Kostecka-Gugała, Anna, Michał Kruczek, Iwona Ledwożyw-Smoleń, and Paweł Kaszycki. "Antioxidants and Health-Beneficial Nutrients in Fruits of Eighteen Cucurbita Cultivars: Analysis of Diversity and Dietary Implications." Molecules 25, no. 8 (2020): 1792. http://dx.doi.org/10.3390/molecules25081792.

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Aging is accompanied by gradual accumulation of molecular damage within cells in response to oxidative stress resulting from adverse environmental factors, inappropriate lifestyle, and numerous diseases. Adequate antioxidant intake is a key factor of proper diet. The study aimed to assess the antioxidant/antiradical capacities of Cucurbita fruits (18 cultivars of the species: C. maxima Duch., C. moschata Duch., C. pepo L., and C. ficifolia Bouché) grown in central Europe. The analyses were based on the FRAP (ferric reducing antioxidant power), CUPRAC (cupric ion reducing antioxidant capacity), and DPPH (2,2-diphenyl-1-picrylhydrazyl radical) assays. The content of phenolic compounds and β-carotene was evaluated with HPLC (high performance liquid chromatography), while the main macro- and micronutrients by ICP-OES (inductively coupled plasma mass spectrometry). The results revealed high intraspecies variability within the Cucurbita genus. The Japanese ‘Kogigu’ fruits were distinguished as extraordinary sources of phenolic compounds, including syringic and protocatechuic acids, catechin, and kaempferol. Another popular cultivar ‘Hokkaido’ exhibited the highest antioxidant and antiradical capacities. Most of the fruits proved to be rich sources of zinc and copper. The obtained data are discussed in the context of optimized nutrition of the elderly and suggest that Cucurbita fruits should become daily components of their diet.
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Anbarasi, K. "Electrochemical and Corrosion Inhibition Studies of Cucurbita Maxima." Oriental Journal of Chemistry 32, no. 4 (2016): 2139–45. http://dx.doi.org/10.13005/ojc/320443.

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Shi, Yuzi, Meng Zhang, Qin Shu, et al. "Genetic Mapping and Identification of the Candidate Gene for White Seed Coat in Cucurbita maxima." International Journal of Molecular Sciences 22, no. 6 (2021): 2972. http://dx.doi.org/10.3390/ijms22062972.

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Seed coat color is an important agronomic trait of edible seed pumpkin in Cucurbita maxima. In this study, the development pattern of seed coat was detected in yellow and white seed coat accessions Wuminglv and Agol. Genetic analysis suggested that a single recessive gene white seed coat (wsc) is involved in seed coat color regulation in Cucurbita maxima. An F2 segregating population including 2798 plants was used for fine mapping and a candidate region containing nine genes was identified. Analysis of 54 inbred accessions revealed four main Insertion/Deletion sites in the promoter of CmaCh15G005270 encoding an MYB transcription factor were co-segregated with the phenotype of seed coat color. RNA-seq analysis and qRT-PCR revealed that some genes involved in phenylpropanoid/flavonoid metabolism pathway displayed remarkable distinction in Wuminglv and Agol during the seed coat development. The flanking InDel marker S1548 was developed to predict the seed coat color in the MAS breeding with an accuracy of 100%. The results may provide valuable information for further studies in seed coat color formation and structure development in Cucurbitaceae crops and help the molecular breeding of Cucurbita maxima.
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Srbinoska, Marija, Nataša Hrabovski, Vesna Rafajlovska, and Snežana Sinadinović-Fišer. "Characterization of the seed and seed extracts of the pumpkins Cucurbita maxima D. and Cucurbita pepo l. from Macedonia." Macedonian Journal of Chemistry and Chemical Engineering 31, no. 1 (2012): 65. http://dx.doi.org/10.20450/mjcce.2012.58.

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Chemical composition of seeds of C. maxima D. and C. pepo L. cultivated in the Republic of Macedonia and physico-chemical characteristics, fatty acid profiles, and sterol and tocopherol contents in pumpkin seed extracts were determined. Higher kernel yield and content of moisture, ash, total nitrogen, proteins and carbohydrates were measured in the C. pepo than in C. maxima seed. The highest extract yield of 487.4 g/kg dry matter was obtained from C. pepo kernel, while 388.2 g/kg dry matter was extracted from C. maxima kernel, when n-hexane was used as solvent. In all extracts, the palmitic, stearic, oleic and linoleic acids were predominant. The linoleic/oleic acid ratio was higher in C. maxima extracts. D7-Sterols were predominant in all extracts, while D5-sterols content was higher in the whole seed than in the kernel extracts. Higher tocopherol content was determined in the extracts of C. pepo whole seed and kernel (153.79 mg/kg and 117.81 mg/kg, respectively), than in those of C. maxima (121.24 mg/kg and 117.55 mg/kg, respectively). In all extracts γ-tocopherol content was higher than α-tocopherol.
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Dissertations / Theses on the topic "Cucurbita, chemistry"

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Ramos, Gabriel Vieira. "Validação de um método para análise de cucurbitacina B por CLAE-UVA/DAD em abóboras (Cucurbita sp.)." Niterói, 2018. https://app.uff.br/riuff/handle/1/5473.

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Submitted by Biblioteca da Faculdade de Farmácia (bff@ndc.uff.br) on 2018-01-11T12:31:55Z No. of bitstreams: 1 Dissertação Gabriel Ramos.pdf: 1422759 bytes, checksum: ed9596ebc8d11e25a874397e974e57ff (MD5)<br>Made available in DSpace on 2018-01-11T12:31:55Z (GMT). No. of bitstreams: 1 Dissertação Gabriel Ramos.pdf: 1422759 bytes, checksum: ed9596ebc8d11e25a874397e974e57ff (MD5)<br>Cucurbita moschata (abóbora sergipana), C. maxima (abóbora moranga) e Tetsukabuto (abóbora japonesa) são espécies vegetais pertencentes à família Cucurbitaceae, geralmente utilizadas como alimento, porém com propriedades nutracêuticas principalmente nas sementes. Algumas dessas propriedades terapêuticas se devem a presença de um grupo de substâncias denominadas cucurbitacinas. A cucurbitacina B – Cuc B – é um triterpeno que pode ser encontrado livre ou glicosilado e que vem sendo estudada quanto ao seu potencial farmacológico, mas ainda apresenta escassez de dados quanto às suas ocorrência e concentrações nas diferentes espécies e partes dos frutos. As cascas, bagaços e sementes são alguns dos resíduos do processamento agroindustrial de frutas e hortaliças que são gerados em grande quantidade e subutilizados na alimentação humana e animal. O presente trabalho objetivou desenvolver um método de produção de farinhas das sementes, da polpa e da casca das abóboras das espécies C. moschata, C. maxima e do híbrido Tetsukabuto, além de avaliar a qualidade do processo de obtenção das farinhas sob o ponto de vista microbiológico. Foi desenvolvido um método analítico para a detecção de Cuc B nessas amostras baseado no método QuEChERS, utilizandoacetonitrila/água (70:30) na extração e MgSO4, C18 e aluminana purificação, e análise por cromatografia líquida de alta eficiência (CLAE) com detecção por UV/DAD. Foi realizada também uma avaliação das concentrações de Cuc B nas sementes de abóboras provenientes de campos experimentais da Embrapa que tem genética conhecida. O método desenvolvido foi validado considerandoa seletividade, linearidade, faixa de trabalho (0,15 a 100,88 μg.mL-1), limites de detecção e quantificação na matriz de 0,602 μg.g-1 e 1,985 μg.g-1, respectivamente; a média da % recuperação da matriz abóbora foi de 83,54% (exatidão) e o coeficiente de variação foi 3,18 % (precisão). A análise das quatro amostras de sementes de abóboras aplicando o método validado no laboratório evidenciou uma concentração bem superior de Cuc B do que nas sementes de frutos adquiridos no comércio varejista. Isso comprovou a eficiência do aprimoramento genético e fenotípico realizado nas primeiras amostras. O valor médio de Cuc B nestas sementes foi de 5,652 μg.g-1 enquanto que a concentração de Cuc Bna farinha das sementes de C. moschata foi de 0,752 μg.g-1. Na espécie C. maxima e no híbrido Tetsukabuto não foram detectado a presença de cucurbitacina.<br>Cucurbita moschata, C. maxima and Tetsukabuto are plant species belonging to the Cucurbitaceae family, generally used as food, but with nutraceutical properties mainly in the seeds. Some of these therapeutic properties are due to the presence of a group of substances called cucurbitacins. Cucurbitacin B - Cuc B - is a triterpene that can be found free or glycosylated and that has been studied for its pharmacological potential, but still presents a scarcity of data regarding its presence and concentrations in the different species and parts of the fruits. The peels, bagasses and seeds are some of the residues of agroindustrial processing of fruits and vegetables that are generated in great amount and underutilized in human and animal feeding. The present work aimed to develop a method for the production of flours of seeds, pulp and peels of the pumpkins of C. moschata, C. maxima and Tetsukabuto hybrid and to evaluate the quality of this process from the microbiological point of view. A method for the detection of Cuc B has been developed in some flours of these samples based on the QuEChERS method, using acetonitrile/water (70:30) in the extraction and MgSO4, C18 and aluminum in the clean up, and analysis by quantification by high performance liquid chromatography (HPLC) with UV/DAD detection. An evaluation of Cuc B was also carried out in pumpkin seeds from experimental fields of Embrapa that has known genetics. The method developed was validated for selectivity, linearity, work range (0.15 to 100.88 μg.mL-1), detection and quantification in the matrix of 0.602 μg.g-1 and 1.985 μg.g-1, respectively; the average of % recovery of the pumpkin matrix was 83.54% (accuracy) and the coefficients of variation was 3.18% (precision). The analysis of the four samples of pumpkin seeds applying the validated method in the laboratory, evidenced a concentration higher of Cuc B in relation to the seeds fruits purchased in the retail trade. This proved the efficiency of the genetic and phenotypic improvement carried out in these first samples. The average value of Cuc B in these seeds was 5.652 μg.g-1 while the concentration of Cuc B in the seeds flour of C. moschata was 0.752 μg.g-1. In the species C. maxima and in the hybrid Tetsukabuto weren’t detected the presence of cucurbitacin.
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White, Tim Chemistry Australian Defence Force Academy UNSW. "Supramolecular chemistry and synthesis of Cucurbit[n]uril." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Chemistry, 2003. http://handle.unsw.edu.au/1959.4/38643.

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The recently discovered cucurbit[n]uril are a range of macrocyclic hosts which have enormous potential in industrial, medical and academic applications. Cucurbit[n]uril have a rigid repeating structure of methylene bridged glycouril, which give cucurbit[n]uril their gourd like shape of a cavity with two carbonyl fringed portals. In this thesis the host-guest binding abilities of three cucurbit[n]uril (n = 6, 7, 8) have been examined for a range of potential guests. These guests ranged from simple alkyl amines through globular alkyl and carboranyl amines to bipyridyl systems. In total 45 guest molecules where examined. Most of the guests examined where either cationically charged, capable of hydrogen binding, contained a substantial molecular dipole, or a combination of these. Furthermore, all of the potential guests examined had some solubility in an acidified aqueous sodium sulfate solution within which the host-guest properties were examined. It was generally found that the larger guests did have selectivity for the larger hosts. However, when the host became too large weaker complexes would form and for the range of materials examined here cucurbit[7]uril was found to be the 'best' host system. In one example, p-xylene diamine, a 2:1 complex with cucurbit[8]uril was observed. While not the focus of this work a new rapid purification method was developed for the cucurbit[n]uril using different metal ions to either solubilise or precipitate the different cucurbit[n]uril. In the second part of this work these same guest molecules where used as potential templates in the synthesis of cucurbit[n]uril. Surprisingly the guests that bound strongly to an individual host did not seem to template the cucurbit[n]uril synthesis at all. Rather these strong binders inhibited the reaction such that little or no cucurbit[n]uril formed under the reaction conditions studied. However, several examples provided excellent template results. Indeed the results indicate that guests which bound with intermediate rates of exchange are the best templates and using templates under these conditions we have been able to produce cucurbit[7]uril as 46% by mass of the total cucurbit[n]uril product. This is the highest yield ever recorded for cucurbit[7]uril and it is the first example of cucurbit[7]uril being the major product of this condensation reaction. In an another example cucurbit[8]uril formed 18% of the product an increase of 150% over the standard reaction conditions. While studying both the template reactions and the host-guest binding properties of the cucurbit[n]uril a new supramolecular form, an 'inverse rotaxane' was discovered. Inverse rotaxanes are not held in place by large blocking groups, rather the molecular structure encapsulated by the cucurbit[n]uril host prevents decomplexation of the axle.
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Andersson, Samir. "Supramolecular chemistry based on redox-active components and cucurbit[n]urils." Doctoral thesis, KTH, Organisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-24730.

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This thesis describes the host-guest chemistry between Cucurbit[7]uril (CB[7]) and CB[8] and a series of guests including bispyridinium cations, phenols and  napthalenes. These guests are bound to ruthenium polypyridine complexes or ruthenium based water oxidation catalysts (WOCs). The investigations are based upon utilizing the covalently linked photosensitizer and the electronic effects and chemical processes are investigated.<br>QC 20100927
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Tian, Feng. "Dynamic supramolecular assemblies on cucurbit[8]uril 'handcuff' surfaces." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610875.

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Rabbani, Ramin. "Cucurbit[8]uril: New Recognition Features and Applications in Chemosensing and Catalysis." Ohio University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1617370414505626.

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Ling, Xiaoxi. "Cucurbit[n]urils in Self-Assembling Molecular Devices: Thermodynamic and Kinetic Considerations." Ohio University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1377319288.

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Ren, Xiaohe. "Cucurbit[n]uril-engineered nano-constructs for molecular sensing." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/287939.

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Surface-enhanced Raman scattering (SERS) spectroscopy is a powerful analytical technique for ultrasensitive detection of chemicals and biomolecules. As the high sensitivity of SERS requires analytes to be in close contact with a plasmonic substrate, the detectionof analyte molecules with low chemical affinity towards the substrate is thus limited. Cucurbit[n]uril (CB[n]) exhibits strong and selective encapsulation of various guest molecules into its barrel-shaped cavity. In addition, it can function as a precise rigid spacer between metallic nanoparticles (NPs). The larger homologue CB[8] can simultaneously sequester two guest molecules to form ternary complexes, allowing for tailoring of the chemical environment of its cavity to trap specific analytes. CB[n] aggregated metallic NPs provide a powerful platform for the detection of a wide variety of molecules. However, the colloidal instability of this system requires the measurement to be finished within 60 min after the preparation of the substrate. In addition, in situ measurements may involve environments that affect such self-assembly processes. For example, the possible displacement of analytes in the nanogap by non-analyte moieties can give rise to fluctuating backgrounds. Therefore, a SERS substrate that can provide the same levels of detection and functionality but eliminates the need for aggregation is of great demand. This thesis mainly focuses on the preparation and characterisation of CB[n]-engineered nanostructures as SERS substrates with great colloidal stability, high SERS enhancements and sensitivities. Other applications of the prepared nanostructures such as peptide separation and high-performance catalysis are also discussed. In the first chapter, the historical development and the remaining challenges in the field of SERS are discussed. Three types of the most commonly used SERS substrates are introduced, followed by the introduction of rationally designed nanoplatforms for molecules with low chemical affinity towards metallic surfaces. In addition, CB[n] host guest complexation, examples of CB[n]-engineered nanostructures and the application of these nanostructures in SERS sensing are also discussed. The second chapter demonstrates the preparation of surface-bound CB[8] catenanes on silica NPs, where CB[8] is employed as a tethered supramolecular "receptor" to selectively capture target guest molecules. More specifically, CB[8] is threaded onto a methyl viologen (MV2+) axle and immobilised onto silica NPs with a surface density up to 0.56 nm$^{−2}$. Its use as an efficient and recyclable nanoplatform for peptide separation is demonstrated. The peptides captured by the catenanes can be released by reversible single-electron reduction of MV$^{2+}$. The entire process demonstrates high recoverability. Continued in the third chapter, a highly stable free-standing molecular sensor that exploits a catenane-engineered nanostructure is described. CB[8] is tethered onto spiky γ-Fe2O3@Au NPs in a similar approach, to collect target analytes from aqueous media. These target analytes can be detected with high sensitivities, on account of the high SERS enhancement (on the order of 10$^{8}$) of the spiky NPs. This CB[8] catenane-based molecular sensor provides a powerful SERS substrate that shows great promise in the detection of versatile chemicals, biomolecules, controlled substances and auxiliary diagnostics of various diseases. The fourth chapter introduces a facile preparation of monodispersed γ-Fe2O3@Au magnetic nanoraspberry NPs using a one-pot seeded growth method. The obtained nanoraspberry NPs show excellent colloidal stability and high SERS enhancement factors (on the order of 10$^{10}$). By immobilising a dense layer of CB[n]s onto the surface of nanoraspberry NPs, a new type of CB/Au NP SERS substrate is obtained. CB[n]s are located perpendicularly to the NP surface and their cavity maintain the capability to sequester guest molecules from aqueous media. More versatile molecules (both electron rich and electron deficient molecules) can thus be detected with high sensitivities. We envisage that this nanoraspberry-based molecular sensor will provide a powerful platform for SERS detection in various fields, such as chemical and biomolecule analysis, illegal drug detectionand pre-clinical/clinical diagnosis. The fifth chapter focuses on the preparation of CB[7]-based catalytic microreactors, where metallic NPs are immobilised onto microchannels via supramolecular interaction of methyl viologen@CB[7]. This microreactor exhibits remarkable catalytic activity on account of the high surface area to volume ratio of the microchannels and metallic NPs. Superior to most conventional heterogeneous catalytic reactions, separation post reaction and complicated recycling steps of the catalysts are not required. Moreover, CB[7] can complex a variety of metallic NPs onto its portal (e.g. gold, silver, palladium, quantum dot), providing a multifunctional in situ catalysis platform. In the end, a concluding chapter summarises the presented work, also giving a brief outlook of the potential future work.
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Liu, Chenyan. "Hierarchical supramolecular assemblies based on host-guest chemistry between cucurbit[n]uril and azobenzene derivatives." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289435.

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Cucurbit[8]uril (CB[8]) has attracted great interest in the cucurbit[n]uril (CB[\textit{n}]) family on account of its capability to simultaneously accommodate two guests inside its cavity, to form strong yet dynamic ternary complexes. Owing to the photo-induced \textit{trans} to \textit{cis} isomerisation property, azobenzene (Azo) derivatives have been widely employed in several host-guest systems, leading to various light-responsive materials. This thesis focuses on CB[8]-based ternary complexes, especially those involving Azo derivatives. These systems can be exploited as a platform to hierarchically fabricate supramolecular constructs, including crystalline structures and composite materials. Specifically, novel morphology-controlled (1D needle-like, 2D sheet-like) crystals have been prepared by adjusting the assembly of Azo-CB[8] complexes, which can be further developed to oriented macroscopic free-standing crystalline pillars grown from a glass surface. Next, a composite micelle-nanoparticle complex has been prepared utilising Azo-CB[8] assemblies, which demonstrates $\sim$90$\%$ efficiency in surfactant recycling. Finally, an organic CB[8]-mediated hydrogel reinforced by inorganic nanowires has been prepared. This hybrid structure shows increased stiffness due to various supramolecular interactions. Chapter 1 gives a brief introduction to CB[\textit{n}] host-guest chemistry with emphasis on CB[\textit{n}]-based crystalline structures and CB[8] ternary complexes. Recent progress of Azo-based host-guest chemistry is then reviewed. In addition, shape-controlled crystals formed \textit{via} supramolecular interactions are discussed at the end of the chapter. Chapter 2 focuses on the crystalline structure of the 1:2 homoternary complex formed between CB[8] and a methyl orange (MO) guest, which is the fastest CB[8]-based crystallisation to date. As a commonly used pH indicator, MO possesses an azobenzene moiety with both an electronically positive amino group and an anionic sulfonate group. At low pH values, formation of the homoternary complex 2MO@CB[8] occurs, serving as a 'tectonic' building block, which rapidly stacks into a herringbone arrangement. The intermolecular and intercomplex interactions inside 2MO@CB[8] crystals are discussed, whereby the CB[8] macrocycle orients the electrostatic charges on MO guests resulting in the repulsive interactions being shielded; this in turn leads to fast electrostatically-driven crystal growth. The 2MO@CB[8] system provides a promising approach for designing ultrarapid crystallisation systems derived from CB[\textit{n}] host-guest complexes. Moreover, the host-guest chemistry between CB[8] and a variety of Azo derivatives with different functional groups is discussed, demonstrating the influence of guest structures on their crystalline behaviours. Chapter 3 further explores the mechanism of 2MO@CB[8] crystallisation through a series of experimental and computational methods. Control over the crystal shape, length and growth rate can be achieved in a facile manner whilst maintaining the same (internal) unit cell. Therefore, the properties of the macro-scale crystals can be tuned at the molecular level through adjusting the assembly of 2MO@CB[8] building blocks. For example, tuning the ionic strength of the solution enables a second growth dimension, yielding 2D crystals with sheet-like and more complex morphologies. Furthermore, our understanding of oriented electrostatics provided by the homoternary tecton can then be exploited to prepare oriented macroscopic free-standing crystalline pillars grown from a glass surface at room temperature. Next, CB[8] ternary complexes have been employed as 'bridges' to link (organic) soft and (inorganic) hard materials together, resulting in composite materials. In chapter 4, a micelle-nanoparticle complex (\textbf{MNC}) structure has been assembled \textit{via} host-guest interactions between Azo-functionalised, cargo-loaded micelles and magnetic SiO$_2$ nanoparticles (NPs) functionalised with CB[8] catenanes. Owing to the photo-responsive and magnetic properties, \textbf{MNCs} can be exploited to recycle detergents (micelles) from aqueous solution. This is followed by the controlled release of the encapsulated hydrophobic molecules inside the micelle cavity. In this process, both the micelles and NPs can be recycled efficiently. The novel \textbf{MNC} structure provides a promising approach to recycle versatile drug carriers through host-guest chemistry. Chapter 5 introduces a CB[8]-based hydrogel in which inorganic nanowires (NWs) are employed to enhance the gel stiffness. The supramolecular hydrogel is comprised of methylviologen-functionalised poly(vinyl alcohol) (PVA-MV), hydroxyethyl cellulose with naphthyl moieties (HEC-Np) and CB[8]. The gel structure is effectively enhanced by the framework supporting effects of CePO$_4$ NWs and additional hydrogen bonding interactions between NWs and PVA-MV/HEC-Np polymers. The high aspect ratio NWs serve as a 'skeleton' for the network, providing extra physical crosslinks. This results in a single continuous phase hybrid supramolecular network with improved strength, showcasing a general approach to reinforce soft materials. Finally, this thesis closes with a summary and perspective chapter, concluding the present work and highlighting an insight towards future work. Utilising CB[8] ternary complexes, various supramolecular constructs can be prepared through hierarchical self-assemblies, leading to a wide variety of composite systems and functional materials in the future.
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McCune, Jade Alexis. "Functionalisation of cucurbit[n]uril and exploring deep eutectic solvents as a medium for supramolecular chemistry." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/278225.

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Das, Anjali Devi. "Study of ternary complexes of cucurbit[8]uril and their applications in self diagnostic composites." Doctoral thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/32631.

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Self-assembly in supramolecular systems has profound implications on creating the next generation of smart materials, with potential applications in self healing, energy storage, stimuli responsive hydrogels and sensors. Macrocyclic receptors that form host guest complexes with organic molecules, provide a unique platform for the formation of tailor made materials with programmable properties for specific applications. The cucurbiturils are one such class of receptors that have garnered increasing interest in the last decade due to their unique guest binding abilities. Cucurbit[8]uril, as one of the larger homologues, is a particularly appealing host molecule for functional materials, capable of forming ternary complexes with suitable guests. The main scope of this thesis is to design and employ host guest systems based on the macrocyclic host cucurbit[8]uril as supramolecular probes to identify early stage damage in carbon fibre reinforced composite materials. Chapter 2 outlines the main project, the development of a novel system for early stage damage detection in a fibre reinforced polymer composite. CB[8] has the ability to form heteroternary complexes of high stability of two different guests in polar environments. In the reported system, CB[8] encapsulates two pendant molecules in the matrix, a donor and a fluorescent acceptor forming a complex by stabilising a charge transfer pair within its cavity. The emission of the probe is suppressed within the ternary complex via photo induced electron transfer. The application of stress causes the weak supramolecular link to break apart, and in turn the fluorescence of the probe is reinstated. Several ternary complexes of the host molecule and fluorescent guest molecules were investigated and a Perylene imide (PER) - Cucurbit[8]uril (CB[8]) based system was found to be best suitable as a strain sensor. Studying the photophysical behaviour of the complex showed that the fluorescence of the PER - CB[8] complex was effectively switched off upon the complexation of a second guest molecule such as dibenzofuran or azobenzene. The supramolecular complex cross-linking the polymer chains was seen to provide a fluorescence response induced by strain even if present in a very low amount of 10−6 mol kg−1 , preserving the mechanical characteristics of the matrix. In addition to uniaxial compressive and tensile testing, the specimens were subjected to fatigue to assess the performance of the material under similar conditions during actual use. The ability to detect fatigue damage is especially important, due to it being one of the major causes of in-service failure of materials. Carbon fibreepoxy composite materials are widely used in the structures of aircraft, robots and other machines because of their high specific strength. Self-diagnosis is potentially an important tool for Non-Destructive Evaluation (NDE) of such composite materials used for purposes where structural integrity is absolutely essential. This work has been recently published in ACS Applied Polymer Materials in 2019 and was recognised by ACS as Editor's Choice. While studied as a versatile host molecule for molecular recognition, cucurbit[8]uril also offers a platform for the development of supramolecular organic frameworks and the formation of porous materials. In this context, the fundamental study of the stoichiometry and geometry of CB[8], its complexes in the solid state and the exploration of new binding motifs is pivotal. Indeed, due to their differential solubility, CB[8] complexes have proved to be difficult to characterise in the solid state, and limited examples are present in literature. Chapter 3 outlines the synthesis of nanotubular CB[8] assemblies. Organic molecular porous materials, in particular materials with a one-dimensional nanochannel structure have found a diverse range of applications in separation, energy storage, and adsorption. Three tubular frameworks of CB[8] were synthesised through chaperone induced methods and metal coordination. Finally, in a bid to develop better probes for self diagnostic composites, different CB[8] complexes with varying stoichiometry were studied in solution and in the solid state. Several CB[8] host guest systems were extensively studied with the aim to improve upon the damage reporting system reported in Chapter 2, by two main approaches. Firstly, there is an interest to move to near IR dyes due to their improved depth-penetration of light, allowing visualisation of damage deeper within the composite material. Secondly, moving from a 1:1:1 heteroternary complex by accommodating two different guests, to a 2:1 homoternary complex by accommodating two identical guests should provide an advantage by reducing the complexity of the system. Chapter 4 describes the study of the interaction of a series of potential dye molecules with CB[8] that fulfil these categories with the aim of developing improved supramolecular probes for self diagnostic composites. In addition, this chapter also reports three novel crystal structures of CB[8] complexes of varying stochiometry, from a 2:1, 1:1 to an unusual 1:2 complex with respect to the host. Overall, this thesis deals with the design and characterisation of CB[8] based host guest complexes, the study of their photo-physical behaviour and binding in solution, and exploits this behaviour in the design and implementation of a novel approach to the technologically relevant field of damage detection in composites.
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Books on the topic "Cucurbita, chemistry"

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Tao, Zhu, Xin-Long Ni, Xin Xiao, and Hang Cong. Supramolecular Assemblies of Cucurbit[n]urils with Metal Ions: Coordination, Structures and Properties. Springer, 2015.

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Book chapters on the topic "Cucurbita, chemistry"

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Ayyildiz, Hamide Filiz, Mustafa Topkafa, and Huseyin Kara. "Pumpkin (Cucurbita pepo L.) Seed Oil." In Fruit Oils: Chemistry and Functionality. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-12473-1_41.

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Ni, Xin-Long, Xin Xiao, Hang Cong, and Zhu Tao. "Cucurbit[n]uril Chemistry." In SpringerBriefs in Molecular Science. Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-46629-2_1.

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Jacks, T. J. "Cucurbit Seed Protein and Oil." In Plant Proteins: Applications, Biological Effects, and Chemistry. American Chemical Society, 1986. http://dx.doi.org/10.1021/bk-1986-0312.ch020.

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Kim, Kimoon, Dinesh Shetty, and Kyeng Min Park. "Robust Host-Guest Chemistry of Cucurbit[n]uril." In Macrocyclic and Supramolecular Chemistry. John Wiley & Sons, Ltd, 2016. http://dx.doi.org/10.1002/9781119053859.ch6.

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Hoogland, D., J. Liu, and O. A. Scherman. "Chapter 14. Cucurbit[8]uril-based Polymeric Materials." In Monographs in Supramolecular Chemistry. Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788015967-00407.

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Baek, Kangkyun, and Kimoon Kim. "Chapter 15. Cucurbit[6]uril-based Polymer Nanocapsules and Thin Films." In Monographs in Supramolecular Chemistry. Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788015967-00426.

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Kaifer, Angel E., Carlos Peinador, and Marcos D. García. "Chapter 12. Cucurbit[n]uril-based (n=7 and 8) (Supra)molecular Switches." In Monographs in Supramolecular Chemistry. Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788015967-00324.

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King, K., K. Sokolowski, X. Ren, and O. A. Scherman. "Chapter 13. Functionalisation and Self-assembly of Nanoparticles through Cucurbit[n]uril-based Binding Motifs." In Monographs in Supramolecular Chemistry. Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788015967-00362.

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Murkli, Steven, and Lyle D. Isaacs. "Chapter 19. Cucurbit[n]uril-type Receptors: Influence of Building Block Exchange, Deletion, and Augmentation." In Monographs in Supramolecular Chemistry. Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788015967-00505.

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Reany, O., and E. Keinan. "Chapter 11. Machines, Switches and Delivery Devices Based on Cucurbit[6]uril and Bambus[6]uril." In Monographs in Supramolecular Chemistry. Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788015967-00283.

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Conference papers on the topic "Cucurbita, chemistry"

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Saridewi, Nanda, Heri T. Syaputro, Isalmi Aziz, Dasumiati Dasumiati, and Biaunik N. Kumila. "Synthesis and characterization of ZnO nanoparticles using pumpkin seed extract (Cucurbita moschata) by the sol-gel method." In 4TH INTERNATIONAL SEMINAR ON CHEMISTRY. AIP Publishing, 2021. http://dx.doi.org/10.1063/5.0051826.

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Nair, Bhagyalakshmi, Praful Patil, Sandeep Waghulde, Pravin Naik, Nilesh Gorde, and Tushar Baviskar. "ANTI MICROBIAL ACTIVITY OF SEED EXTRACT OF CUCURBITA PEPO ." In The 21st International Electronic Conference on Synthetic Organic Chemistry. MDPI, 2017. http://dx.doi.org/10.3390/ecsoc-21-04793.

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Wagner, Andreas, Erwin Reisner, Nina Heidary, et al. "1 Host-guest Chemistry Meets Electrocatalysis: Cucurbit[6]uril on a Au Surface as Hybrid System in CO2 Reduction." In nanoGe Fall Meeting 2019. Fundació Scito, 2019. http://dx.doi.org/10.29363/nanoge.ngfm.2019.070.

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