Die Cyclisierung der aus den entsprechenden dichlorierten Polyethern und Na‐p‐nitrophenolat erhaltenen Diarylpolyoxaalkane (I) zu den trans‐Titelverbindungen (II) gelingt durch Reduktion zum Diamin und anschließende Oxidation in Gegenwart von tert.‐Butanolat in tert‐Butanol/DMSO.

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The photochromic reaction of spiropyran *» merocyanine has been studied with l'-octadecyl-3',3'-dimethyl-6-nitrospiro-[2H-1 -benzopyran-2,2'-indoline] (SSP) incorporated in Langmuir-Blodgett (LB) films prepared in a mixed film with stearic acid, arachidic acid, and tripalmitine. Time-resolved fluorescence spectra and decay curves of SSP and its photoisomer, merocyanine (SMC), were measured with a picosecond time-correlated, single-photon-counting apparatus. When SSP in LB films was excited at 360 nm, two fluorescence bands were observed: one has a maximum at 660 nm, and the other has a relatively weak band at 530 nm. We assigned them respectively to the fluorescence band of SMC and an intermediate X as a precursor of SMC. The rigidity of the medium surrounding photochromic molecules is an important factor in determining the rate of reversible photoconversion of SSP -*-* SMC.

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