Series of Cd(II) Metal–Organic Frameworks Based on a Flexible Tripodal Ligand and Polycarboxylate Acids: Syntheses, Structures, and Photoluminescent Properties

Abstract

Five novel metal−organic frameworks with a 1,3,5-tris-(triazol-1-ylmethyl)-2,4,6-trimethylbenzene (tttmb) flexible tripodal block, n a m e l y , { [ C d ( t t t m b ) 5) (H 2 atc = 1,3-adamantanedicarboxylic acid, H 2 tbi = 5-tert-butylisophthalic acid, H 2 bdc = 1,4-benzenedicarboxylic acid, H 3 btc = 1,2,4-benzenetricarboxylic acid, and H 4 btec = 1,2,4,5-benzenetetracarboxylic acid), have been synthesized. Complex 1 exhibits a two-dimensional structure with left-and right-handed helical chains arranged alternately. Complex 2 displays an intricate two-dimensional framework containing three layers with a 3,4,7-connected topology. It is notable that tbi 2− takes on five different coordination modes in 2. Complex 3 presents a 3D 3,4-connected network with a point symbol of (6 3 ) 2 (6 4 •8 2 ) 2 (6 3 •8 3 ). The structure of complex 4 is a self-penetrating 3D 3,4,8-connected framework with left-and right-handed helical chains arranged alternately. Complex 5 shows a 3D pillar-layered framework, which can be simplified as a 3,4,5-connected 3D topology with a Schlafi symbol of (5 3 )(5 2 •6 2 •7•9)(5 5 •6 2 •7 2 •8). Moreover, the investigation of photoluminescence properties reveals that complexes 1−5 show different fluorescent behaviors.

Four transition metal complexes constructed with mixed mercaptotetrazole and 4,4′-bipyridine ligands

“…While Zn2 is in a distorted tetrahedral coordination geometry provided by one hydroxy, one mtms, and two bpy ligands. The Zn-N bond distances range from 2.022(4) to 2.215(4) Å , and the Zn-S bond distance is 2.3215(16) Å , which are similar to other complexes [23,24]. The binuclear units link each other by bpy ligands (Scheme 2, mode I, II) to form a 1D zigzag chain along the c axis.…”

“…1a, complex 1 exhibits a dimeric structure in which two Cd atoms are bridged by two acetates; one adopts syn-syn mode (l 2 , g 2 -carboxylato), and the other coordinates through one O atom (l 2 , g 1 -carboxylato), which is different to other previously reported binuclear Cd(II) complexes [24]. The CdÁÁÁCd distance is 3.9462 Å .…”

“…It is well known that Cd(II) complexes can exhibit interesting luminescence properties [8,24]. The solid-state luminescence of the free Na 2 mtms ligand and complexes 1 and 2 was investigated at room temperature and is shown in Fig.…”

Lanthanide coordination compounds with 2,2′-bipyridine-6,6′-dicarboxylate: Synthesis, crystal structure, luminescence and magnetic property

“…3b), upon excitation at 330 nm, no characteristic peaks are observed at room temperature except for two broad emission bands at 438 and 546 nm, respectively. The broad emission band at 438 nm originates from an intraligand transition [45][46][47][48]. It is red-shifted about 52 nm compared with the ligand due to both the deprotonation of carboxylic acid and the coordination action of carboxylate groups to metal centers [49,50].…”

Two highly connected frameworks and one polythreading architecture based on multidentate N-donor ligands: Syntheses, structures, characterizations and photoluminescent properties

“…S8). The emission peaks of the free 4,4′-tmbpt, H 3 btc and H 4 btec are located at 458 nm (λ ex = 337 nm), 395 nm (λ ex = 350 nm) [40], and 368 nm (λ ex = 313 nm) [41], respectively, which may be attributed to the π*-n or π*-π transition [42,43]. The emission peaks of compounds 2 and 3 are observed at 548 nm (λ ex = 353 nm) and 438 nm (λ ex = 344 nm), respectively.…”