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Your search keyword '"NMR CHEMICAL-SHIFTS"' showing total 2 results
Start Over Descriptor "NMR CHEMICAL-SHIFTS" Publisher royal society of chemistry
2 results on '"NMR CHEMICAL-SHIFTS"'

1. Computationally-Inspired Discovery of an Unsymmetrical Porous Organic Cage

Author

Andrew I. Cooper, Lukas Turcani, Enrico Berardo, Ben M. Alston, Kim E. Jelfs, Marcin Miklitz, Michael E. Briggs, Rebecca L. Greenaway, Rob Clowes, Michael J. Bennison, The Royal Society, Engineering & Physical Science Research Council (EPSRC), Engineering & Physical Science Research Council (E, and Commission of the European Communities

Subjects
Technology, Materials science, Chemistry, Multidisciplinary, Imine, Materials Science, Topicity, DENSITY FUNCTIONALS, Materials Science, Multidisciplinary, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Physics, Applied, NMR CHEMICAL-SHIFTS, Crystallinity, Molecular dynamics, chemistry.chemical_compound, DESIGN, Computational chemistry, Diamine, 10 Technology, Structural isomer, General Materials Science, Nanoscience & Nanotechnology, BASIS-SETS, Science & Technology, 02 Physical Sciences, Physics, Condensation, H-1, Microporous material, 021001 nanoscience & nanotechnology, DIFFUSION, 0104 chemical sciences, Amorphous solid, Chemistry, chemistry, SELECTIVITY, MOLECULAR-DYNAMICS, Physical Sciences, FORCE-FIELD, Science & Technology - Other Topics, SHAPE, 0210 nano-technology, 03 Chemical Sciences
Abstract

A completely unsymmetrical porous organic cage was synthesized from a C2v symmetrical building block that was identified by a computational screen. The cage was formed through a 12-fold imine condensation of a tritopic C2v symmetric trialdehyde with a di-topic C2 symmetric diamine in a [4+6] reaction. The cage was rigid and microporous, as predicted by the simulations, with an apparent Brunauer-Emmett-Teller surface area of 578 m2 g-1. The reduced symmetry of the tritopic building block relative to its topicity meant there were 36 possible structural isomers of the cage. Experimental characterization suggests a single isomer with 12 unique imine environments, but techniques such as NMR could not conclusively identify the isomer. Computational structural and electronic analysis of the possible isomers was used to identify the most likely candidates, and hence to construct a 3-dimensional model of the amorphous solid. The rational design of unsymmetrical cages using building blocks with reduced symmetry offers new possibilities in controlling the degree of crystallinity, porosity, and solubility, of self-assembled materials.

Published
2018

2. Functionalizing natural polymers with alkoxysilane coupling agents: Reacting 3-glycidoxypropyl trimethoxysilane with poly(γ-glutamic acid) and gelatin

Author

Luca Gabrielli, Louise S. Connell, Laura Russo, Laura Cipolla, Julian R. Jones, Oliver Mahony, Connell, L, Gabrielli, L, Mahony, O, Russo, L, Cipolla, L, Jones, J, and Engineering & Physical Science Research Council (EPSRC)

Subjects
SILOXANE HYBRIDS, food.ingredient, Polymers and Plastics, Carboxylic acid, Polymer Science, Biomedical Engineering, Epoxide, Bioengineering, 02 engineering and technology, SIMPLE NUCLEOPHILES, 010402 general chemistry, 01 natural sciences, Gelatin, Biochemistry, NMR CHEMICAL-SHIFTS, BONE REGENERATION, chemistry.chemical_compound, TISSUE REGENERATION, food, Nucleophile, Polymer chemistry, Organic Chemistry, CHIM/06 - CHIMICA ORGANICA, CHITOSAN MEMBRANES, Organic chemistry, BIOACTIVE GLASS, chemistry.chemical_classification, Science & Technology, Aqueous solution, Polymers and Plastic, Polymer, 021001 nanoscience & nanotechnology, 0104 chemical sciences, MULTIFUNCTIONAL MATERIALS, chemistry, Covalent bond, Physical Sciences, SOL-GEL METHOD, 0210 nano-technology, Hybrid material, IN-VITRO CYTOCOMPATIBILITY, 0303 Macromolecular And Materials Chemistry
Abstract

Hybrid materials, with co-networks of organic and inorganic components, are increasing in popularity due to their tailorable degradation rates and mechanical properties. To increase mechanical stability, particularly in water, covalent bonding must occur between the components. This can be introduced using crosslinking agents such as 3-glycidoxypropyl trimethoxysilane (GPTMS). Attachment of GPTMS to polymers in aqueous conditions is hypothesized to occur by opening of the epoxide ring by nucleophiles on the polymer chain. Despite side reactions that occur between the epoxide ring of GPTMS and water, a range of NMR techniques showed that the carboxylic acid group of poly(γ-glutamic acid) reacted with GPTMS. This result was used to identify the amino acids in gelatin that reacted most rapidly with the GPTMS epoxide ring, confirming that covalent bonding occurred in gelatin–silica hybrid materials.

Published
2017

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