Photochromism of spiroindolinonaphthoxazine. I. Photophysical properties

Abstract

NOR1 Y. C. CHU. Can. J. Chem. 61, 300 (1983). A solution of spiroindolinonaphthoxazine in a common organic solvent shows profound photochromic effect. The colorless form in ethanol displays three absorption bands (-320, 235, 203 nm) in the ultraviolet region of the spectrum. The absorption spectrum of the colored metastable form shows two prominent absorption peaks at 612 and 578 nm. The triplet state energy level of the colorless form is estimated to be in the range from 2.4 X lo4 to 2.1 x 10' cm-' by the triplet-triplet energytransfer method. There exists a thermal equilibrium between the colorless and colored forms. From the measurement of absorbance of the colored form at different temperatures, the standard enthalpy of equilibrium is obtained (AH" = 1500 cm-I). The thermal decay of the colored form to the colorless form depends strongly on temperature. The decay rate increases three times for every 10°C increase in temperature. From these temperature dependence studies of the thermal decay rate, the thermal energy barrier for the colored metastable state to decay to the colorless form is determined to be 6.9 x 10' cm-I.NORI Y. C. CHU. Can. J. Chem. 61, 300 (1983). La spiroindolinonaphthoxazine en solution dans un solvant organique ordinaire montre un effet photochimique marqui. La forme incolore dans l'ithanol prtsente trois bandes d'absorption (-320, 235, 203 nm) dans l'ultraviolet. Le spectre d'absorption de la forme metastable colorie montre deux pics de forte intensiti a 612 et 578 nm. On Cvalue que le niveau d'tnergie de l'itat triplet de la forme incolore est de l'ordre de 2,4 X 10' a 2,l X lo4 cm-' selon la mtthode de transfert d'tnergie triplet-triplet. I1 existe un Cquilibre thermique entre les formes incolore et colorCe. A partir des mesures d'absorptirn de la forme colorCe a diffirentes tempiratures, on obtient I'enthalpie standard d'iquilibre (AH0 = 1500 cm-I). I I disintegration thermique de la forme colorie en la forme incolore dipend fortement de la tempirature. La vitesse de disintegration augmente par un facteur de 3 pour chaque augmentation de tempirature de 10°C. A partir des etudes de l'influence de la temptrature sur la vitesse de disintegration thermique, on a ditermini la barriere d'inergie thermique de la disintegration de la forme mitastable colorie en la forme incolore. Cette barrikre est de 6,9 X lo3 cm-I.[Traduit par le journal]

Photochromic behavior of spironaphthoxazine in metal ion-containing solutions

“…These activation energy values are lower than those of the forward and backward reactions from SNO to MC, which were reported to be 100−102 and 81−83 kJ mol −1 , respectively [21,22].…”

Structure of photochromic spiroxazines. I. 1,3,3-Trimethylspiro[indoline-2,3'-[3H]-naphtho[2,1-b][1,4]oxazine]

“…Experimental. The title compound was prepared c(2) according to Chu (1983). Crystallization from c(3) methanol at room temperature produced a mixture c(4) c(5) of platelets and regular octahedral crystals, with c(6) melting points 399.5 and 416 K, respectively (deter-c (7) mined by DSC analysis).…”

Structures of photochromic spiroindolinobenzoxazines and a spiroindolinobenzopyran

“…While photochromic spiroindolinobenzopyrans have been extensively studied (Tyer & Becker, 1970a,b;Aldoshin, Atovmyan, D'yachenko & Gal'bershtam, 1981;Aldoshin & Atovmyan, 1984Aldoshin, Atovmyan & Kozina, 1986, 1987a only a few spectral and structural studies (Chu, 1983;Clegg, Norman, Lasch & Kwak, 1987;Clegg, Norman, Flood, Sallans, Kwak, Kwiatkowski & Lasch, 1991) have been reported for spiroindolinobenzoxazines. Spirooxazines are useful compounds because they show greater durability than spiropyrans on repeated photochromic reactions.…”