Synthesis and Photochromism of Naphthopyrans Bearing Naphthalimide Chromophore: Predominant Thermal Reversibility in Color-Fading and Fluorescence Switch
Synthesis and Photochromism of Naphthopyrans Bearing Naphthalimide Chromophore: Predominant Thermal Reversibility in Color-Fading and Fluorescence Switch
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带有萘二甲酰亚胺发色团的萘并吡喃的合成和光致变色：褪色和荧光开关中的主要热可逆性
DOI：
10.1021/jp208082w
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发表时间：
2011-12-15
影响因子：
3.3
通讯作者：
Zhu, Weihong
中科院分区：
文献类型：
--
作者：
Song, Liwen;Yang, Yuheng;Zhu, Weihong
研究了两种含萘酰亚胺结构的新型光致变色萘并吡喃（Nip 1和Nip 2）在闪光光解条件下的溶液光致变色性能，结果表明，Nip 1和Nip 2具有较高的光致变色响应、快速的热漂白速率和良好的抗疲劳性能.由于萘酰亚胺单元上的N-取代酰亚胺基团不同，萘酰亚胺单元上带有苯基的Nip 2的热漂白速率约为带有正丁基的Nip 1的2倍，表明在萘酰亚胺单元上引入不同的官能团可以调节光致变色性能.在Nip 1和Nip 2中，在萘酰亚胺部分引入的酰亚胺基团的强吸电子效应保持了几个优点：（ii）相对于参比化合物NP，有利于提高反式-顺式（TC）异构体的比例和提高从反式-反式（TT）到TC的转化率，和（iii）导致优选的颜色漂白速率，并以热可逆性完全褪色至它们的无色状态。在NP体系中，TT向TC的缓慢转变过程可能是热回退过程中的主要动力学步骤，导致NP的残留颜色仅在可见光照射下褪色至无色。Nip 1和Nip 2的有色形式的光密度取决于入射光的强度，确保了在眼科镜片和智能窗制造中的可能应用。此外，Nip 1和Nip 2的荧光可以通过闭合和开放形式之间的光诱导转换来打开和关闭。
Two novel photochromic naphthopyrans containing naphthalimide moieties (Nip1 and Nip2) were studied in solution under flash photolysis conditions, exhibiting highly photochromic response, rapid thermal bleaching rate and good fatigue-resistance. Owing to the different N-substituted imide groups at the naphthalimide units, the thermal bleaching rate of Nip2 bearing phenyl on the naphthalimide unit is found to be approximately 2 times that of Nip1 bearing n-butyl, indicating that the photochromic properties can be modulated with introduction of different functional groups on the naphthalimide unit. In Nip1 and Nip2, the strong electron-withdrawing effect of the imide group incorporated at the naphthalimide moiety maintains several merits: (i) shifting absorption bands to longer wavelength, (ii) beneficial to an enhancement in the ratio of transoid-cis (TC) isomer and an increase in the transformation rate from transoid-trans (TT) to TC with respect to reference compound NP, and (iii) resulting in a preferable color bleaching rate and fading absolutely to their colorless state with thermal reversibility. As demonstrated in the system of NP, the slow transformation process from TT to TC might be the predominant dynamic step in thermal back process, leading to the residual color of NP being only faded to its original colorless state by visible light irradiation. The optical densities of colored forms for Nip1 and Nip2 are dependent upon the intensity of incident light, ensuring a possible application in the manufacture of ophthalmic lenses and smart windows. Moreover, the fluorescence of Nip1 and Nip2 can be switched on and off by photoinduced conversion between the closed and open forms.