Steric and electronically biasing substituent effects on the Photoreversibility of novel, 3 '-, 5 '- and 3-substituted indolospirobenzopyrans. Thermal evaluation using H-1 NMR spectroscopy and Overhauser enhancement studies

作者：Roxburgh Craig J^*; Sammes Peter G; Abdullah Ayse

来源：Dyes and Pigments, 2009, 83(1): 31-50.

DOI：10.1016/j.dyepig.2009.03.017

• Spirobenzopyrans
• H-1 NMR spectroscopy and nOe studies
• Steric/electronic substituent control
• Synthesis

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.

• 出版日期2009-10
• 单位中国人民解放军海军医学研究所