文献类型：期刊文献

英文题名：Snapshotting the Excited-State Planarization of Chemically Locked N,N′-Disubstituted Dihydrodibenzo[a,c]phenazines

作者：Chen, Wei[1,2];Chen, Chi-Lin[3];Zhang, Zhiyun[1,2,3];Chen, Yi-An[3];Chao, Wei-Chih[3];Su, Jianhua[1,2];Tian, He[1,2];Chou, Pi-Tai[3]

机构：[1]East China Univ Sci & Technol, Key Lab Adv Mat, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Inst Fine Chem, Shanghai 200237, Peoples R China;[3]Natl Taiwan Univ, Dept Chem, Taipei 10617, Taiwan

年份：2017

卷号：139

期号：4

起止页码：1636

外文期刊名：JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

收录：;EI(收录号：20170603323553);WOS:【SCI-EXPANDED(收录号:WOS:000393355600047)】；

基金：P.-T. Chou thanks the Ministry of Science and Technology, Taiwan, for financial support. H. Tian thanks National 973 Program (2013CB733700) and NSFC/China.

语种：英文

外文关键词：Chains - Excited states - Locks (fasteners)

摘要：For deeper understanding of the coupling of electronic processes with conformational motions, we exploit a tailored strategy to harness the excited-state planarization of N,N'-disubstituted dihydrodibenzo[a,c]phenazines by halting the structural evolution via a macrocyclization process. In this new approach, 9,14-diphenyl-9,14-dihydrodibenzo[a,c]phenazine (DPAC) is used as a prototype, in which the para sites of 9,14-diphenyl are systematically enclosed by a dialkoxybenzene-alkyl-ester or-ether linkage with different chain lengths, imposing various degrees of constraint to impede the structural deformation. Accordingly, a series of DPAC-n (n = 1-8) derivatives were synthesized, in which n correlates with the alkyl length, such that the strength of the spatial constraint decreases as n increases. The structures of DPAC-1, DPAC-3, DPAC-4, and DPAC-8 were identified by the X-ray crystal analysis. As a result, despite nearly identical absorption spectra (onset similar to 400 nm) for DPAC-1-8, drastic chain-length dependent emission is observed, spanning from blue (n = 1, 2, similar to 400 nm) and blue-green (n = 3-5, 500-550 nm) to green-orange (n = 6) and red (n = 7, 8 similar to 610 nm) in various regular solvents. Comprehensive spectroscopic and dynamic studies, together with a computational approach, rationalized the associated excited-state structure responding to emission origin. Severing the linkage for DPAC-5 via lipase treatment releases the structural freedom and hence results in drastic changes of emission from blue-green (490 nm) to red (625 nm), showing the brightening prospect of these chemically locked DPAC-n in both fundamental studies and applications.