期刊
DYES AND PIGMENTS
卷 83, 期 1, 页码 31-50出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.dyepig.2009.03.017
关键词
Spirobenzopyrans; H-1 NMR spectroscopy and nOe studies; Steric/electronic substituent control; Synthesis
资金
- Science and Engineering Research Council (SERC)
Several, novel, 3'-, 5- and 3-substituted indolospirobenzopyrans were prepared and their reversible thermochromic equilibria were investigated by synthesising derivatives with appropriately placed. electronically modifying substituents in both the indole and benzopyran rings as well as by synthesising structural variants that contained sterically hindering (with regard to spiropyran-opening <-> closing) groups, within the spirocyclic ring-system. in addition, structural combinations of the above, involving the syntheses of sterically restricted and electronically biasing substituents were prepared and their effects upon the spiropyran ring-opening <-> closing process investigated. The influence of these steric and electronic substituent effects on the relative quantities of the open- and closed-forms was established using H-1 NMR at six temperature intervals (298, 320, 340, 360, 380 and 410 K). Further elucidation of the stereochemical conformation in these systems was undertaken using nuclear overhauser enhancement (nOe) studies. (C) 2009 Elsevier Ltd. All rights reserved.
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