title: Modulating stepwise photochromism in platinum(II) complexes with dual dithienylethene-acetylides by a progressive red shift of ring-closure absorption.
abstract: To modulate stepwise photochromism by shifting ring-closure absorption of the dithienylethene (DTE) moiety, trans-Pt(PEt3)2(C≡C-DTE)2 [C≡C-DTE = L1o (1oo), L2o (2oo), L3o (3oo), and L4o (4oo)] and cis-Pt(PEt3)2(L4o)2 (5oo) with two identical DTE-acetylides were elaborately designed. With the gradual red shift of ring-closure absorption for L1c (441 nm) → L2c (510 nm) → L3c (556 nm) → L4c (602 nm), stepwise photochromism is increasingly facilitated in trans-Pt(PEt3)2(C≡C-DTE)2 following 1oo → 2oo → 3oo → 4oo. The conversion percentage of singly ring-closed 2co-4co to dually ring-closed 2cc-4cc at the photostationary state is progressively increased in the order 1cc (0%) → 2cc (18%) → 3cc (67%) → 4cc (100%). Compared with trans-arranged 4oo, stepwise photochromism in the corresponding cis-counterpart 5oo is less pronounced, ascribed to either direct conversion of 5oo to 5cc or rapid conversion of 5co to 5cc. The progressively facile stepwise photocyclization following 2oo → 3oo → 4oo is reasonably interpreted by gradually enhanced transition character involving LUMO+1, which is the only unoccupied frontier orbital responsible for further photocyclization of singly ring-closed 2co-4co.
authors.affiliation: State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , Fuzhou, Fujian 350002, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Wen
authors.forename: Jin-Yun
authors.initials: JY
authors.lastname: Wang
authors.forename: Lin-Xi
authors.initials: LX
authors.lastname: Shi
authors.forename: Zhong-Ning
authors.initials: ZN
authors.lastname: Chen
mesh_terms: D060326:Chemistry Techniques, Synthetic; D003500:Cyclization; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010777:Photochemistry / Q000379:methods; D017671:Platinum Compounds / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D017671:Platinum Compounds