Syntheses, structures, photophysical and photochemical research of a series of coordination polymer analogues: [M(pda)(bpeb)]n, (M = Zn, Ni and Co, pda = 1,4-phenylenediacrylate, bpeb = 1,4-bis[2-(4-pyridyl)ethenyl]benzene)

Abstract

Three coordination polymers [M(pda)(bpeb)]_n, 1, 2 and 3 (M = Zn, Ni and Co, bpeb = 1,4-bis[2-(4-pyridyl)ethenyl]benzene, and pda = 1,4-phenylenediacrylate) have been synthesized and characterized. Their structures have been carefully investigated. They are compact 8-fold interpenetrating three-dimensional diamondoid network structures. Photophysical and photochemical investigations have been carried out. The d and θ for the closest CC bonds in 1–3 are: 3.714 Å, 35.62°; 4.007 Å, 47.92° and 3.865 Å, 40.817°, respectively. The distances conform to Schmidt's rule, but the angles deviate far from the 0° required by Schmidt's rule, yet they are less than the 70–100° range for structures that may potentially undergo photochemical reaction. Photochemical studies have confirmed that these compounds are inert to photochemical reactions. Photoaddition cannot occur because the θ angle between the CC double bonds is between 15 and 55°. An extended Schmidt's rule is proposed to consider the influence of the θ angle between 0 and 115° on the photoaddition: θ should be 0–15° for direct photoaddition; or 55–115° for photoaddition after photoisomerization; and θ = 15–55° is very unlikely to undergo photoaddition.