Asymmetric reversible structural switching of a diene coordination polymer promoted by UV-visible light

Construction of olefinic coordination polymer single crystal platforms: precise organic synthesis, in situ exploration of reaction mechanisms and beyond

“…Besides fluorescent switches triggered by light and heat stimuli, that regulated by UV/visible light was also discovered by our group. 133 We reported an asymmetric reversible structural switching between [Zn(L 22 )(A 41 ) 2 ] n ( 113 ) and [Zn 2 (OP 32 )(A 41 ) 4 ] n ( 113′ ) accompanied by fast reversible fluorescence changes between orange and yellow under alternating light at 495 nm and 365 nm (Fig. 30a–c).…”

“…Derivatives of L 17 and L 18 , such as 1,4-bis(2-(3-pyridyl)ethenyl)-benzene (L 20 ), 4,4′-((2,5-dimethyl-1,4-phenylene)bis(ethene-2,1-diyl))dipyridine (L 21 ), 4,4′-((2,5-dioxymethyl-1,4-phenylene)bis(ethene-2,1-diyl))dipyridine (L 22 ) and 5-fluoro-1,3-bis(2-(4-pyridyl)ethenyl)benzene (L 23 ), have been reported to yield CP single crystal platforms ( 104–114 ). 129–134 These diolefinic ligands contain different substituents or have their pyridine nitrogen atoms placed differently, providing access to versatile structural topologies and diverse [2+2] photocycloaddition reactions. Modification of the olefin ligands allows to some extent fine tuning of the alignment of olefin pairs, the orientation, and the distance between proximate CC bonds, providing increased opportunities for the exploration of new physicochemical properties and potential applications.…”

“…160,161 Moreover, an incomplete solid-state [2+2] photocycloaddition reaction involving [Cd 2 (L 22 ) 2 (A 8 ) 2 ·2DMF·0.5CH 3 OH] n ( 112 ) was found to promote the luminescent quenching of inorganic anions. 133 After irradiation with visible light of 495 nm, 112 underwent an incomplete [2+2] photocycloaddition reaction to produce its monocyclobutane product 112-Vis with 87.5% conversion. The incomplete cyclobutane product 112-Vis could enhance the fluorescence sensing ability of Cr 2 O 7 2− and CrO 4 2− compared to 112 (Fig.…”

Photocycloaddition of Zero-Dimensional Metal Halide Hybrids with Reversible Photochromism

“…Since [2 + 2] photocycloaddition brings about great variation in lattice strain and conjugation of π electrons, it has been widely employed in the fields of photomechanical motions and optoelectronic devices including optical writing and data storage without any physical contact. − In principle, parallelly aligned olefinic bonds within less than 4.2 Å can undergo [2 + 2] photocycloaddition according to Schmidt’s criteria. − To satisfy this prerequisite, metal–organic frameworks (MOFs) and coordination polymers (CPs) with wide structural tunability and good designability are often designed to bring olefin group into the required alignment or incorporate olefins in the confined space. ,− …”