Ligands modulated the variable binuclear Cd2-SBUs and structures of four layered coordination frameworks. Issue 23 (27th May 2020)

• Record Type: Journal Article
• Authors: Wang, Mengdie; Zhang, Jian; Sun, Yunkai; Wei, Jing; Tan, Chunhong; Wang, Xiao-Feng
• Is Part Of: CrystEngComm. Volume 22:Issue 23(2020)
• Page Start: 3965
• Page End: 3974
• Publication Date: 2020-05-27
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/d0ce00513d
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : An intriguing modulation of Cd2 (RCOO)4 SBUs and the structural variation in their layered CPs have been observed, which were tuned by di-carboxylate/co-ligand. Abstract : Four layered coordination polymers, namely, [Cd2 (fuma)2 (phen)2 ] (1 ), [Cd2 (BDC)2 (phen)2 ]·2DMF (2 ), [Cd2 (NDC)2 (phen)2 ]·0.5H2 O (3 ), and [Cd2 (NDC)2 (bipy)2 ]·2DMF (4 ) have been synthesized under solvo-thermal conditions (fuma = fumaric acid, H2 BDC = 1, 4-benzenedicarboxylic acid, H2 NDC = 1, 4-naphthalenedicarboxylic acid, phen = 1, 10-phenanthroline, bipy = 2, 2′-bipyridine), which are composed of asymmetric/symmetric binuclear Cd2 (RCOO)4 (phen)2 or Cd2 (RCOO)4 (bipy)2 clusters as secondary building units (SBUs) linked by fuma 2−, BDC 2−, and NDC 2− . Owing to the different steric hindrances of the di-carboxylates, the variation in Cd2 (RCOO)4 (phen)2 SBUs showed an intriguing structural modulation, which was due to the carboxylates adopting dissimilar coordination fashions, while both the terminal phen co-ligands changed from cis - to trans -position. Thus, this further induced twist angles (three neighbouring SBUs connected by the di-carboxylic acid) in the single layer of 1–3 varying from 109.7°, 132.3° to 180° (viewed along the a -axis) and correspondingly, three Cd2 -SBU-based CPs exhibited structural evolution from an undulating to a lamellar layer. When the co-ligand bipy replaced phen, 4 also formed a lamellar layer framework based on the paddle-wheel Cd2 (RCOO)4 (bipy)2 SBUs with bipy perpendicular to the layer rather than the slanted phen in 3 . The luminescence properties of 1–4 have also been explored, and their fluorescence emission mechanism of ligand-to-ligand charge transfer (LLCT) are confirmed by the time-dependent density functional theory (TDDFT) calculations.