A study of the out-of-plane bending vibrations of aromatic CH groups in solution

Chekunov, A. V.; Polyakova, I. A.

doi:10.1007/bf00607803

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“…The bands at 1356 and 1324 cm À1 could be attributed to carbon nitrogen C-N vibrations while the peaks at 751 and 722 cm À1 can be attributed to an out-of-plane C-H di-substituted aromatic system as found in two benzene rings fused onto pyrrole. [39] Infrared spectra of cellulose nanocrystals and coumarin modified cellulose (ESI) clearly indicated the presence of the carbonyl stretching vibrations at 1762 cm -1 and compared with the unmodified CNC spectra, multiple aromatic C¼C stretching vibrations at 1609, 1566, 1485, and 1455 cm À1 become visible. The bands at 1242 and 1209 cm À1 are attributed to carbon oxygen C-O-C ether stretching vibration bands while the signals present at 795 and 763 cm -1 can be attributed to an out-of-plane C-H di-substituted aromatic system as in the case of the benzene ring fraction of the coumarin molecule.…”

Section: Resultsmentioning

confidence: 99%

Coumarin and carbazole fluorescently modified cellulose nanocrystals using a one‐step esterification procedure

2016

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This article is protected by copyright. All rights reserved Fluorescent cellulose nanocrystals with carbazole and coumarin functionalities were synthesised in a one-step esterification reaction using carbazole-9-yl-acetic acid and coumarin-3-carboxylic acid respectively, using a p-toluenesulfonyl chloride/pyridine system. Characterization with elemental analysis, X-ray diffraction, X-ray photoelectron spectroscopy, infrared, absorption and emission spectroscopy, and AFM and TEM imaging confirmed that a high degree of modification could be achieved (up to DS surf = 1.33) while retaining the CNC core crystallinity and nanoparticle dimensions. The present grafting method gives a straightforward way when compared with previously reported fluorescent labelling methodologies and gives an extremely high grafting density while retaining the CNC crystallinity. UV spectroscopy also indicates fluorescence quenching at high grafting densities so that optimal fluorescence does not necessarily mean maximum grafting density. This

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Section: Resultsmentioning

confidence: 99%