R-Substituent-Induced Structural Diversity and Single-Crystal to Single-Crystal Transformation of Coordination Polymers: Synthesis, Luminescence, and Magnetic Behaviors

Abstract

Four Zn(II) coordination polymers (CPs), namely, [Zn(3-bpdb)(MeO-ip)] n (1), [Zn(3-bpdb)(EtO-ip)] n (2), {[Zn(3-bpdb)(n-PrO-ip)]•H 2 O} n (3), and [Zn(3-bpdb)(n-BuOip)] n (4), have been first prepared under solvothermal conditions on the basis of four 5-substituted isophthalic acid ligands including 5-methoxy-1,3-benzenedicarboxylate (MeO-H 2 ip), 5-ethoxy-1,3benzenedicarboxylate (EtO-H 2 ip), 5-propoxy-1,3-benzenedicarboxylate (n-PrO-H 2 ip), and 5-butoxy-1,3-benzenedicarboxylate (n-BuO-H 2 ip) with the help of 1,4-bis(3-pyridyl)-2,3-diaza-1,3butadiene (3-bpdb) as a secondary ligand. CPs 1 and 2 exhibit double pillared layered three-dimensional (3D) structures with non-interpenetrated fsc topology. CP 3 possesses a two-dimensional (2D) terrace layered structure with (4 2 .6)(4 2 .6 7 .8) topology, while CP 4 features a one-dimensional (1D) infinite tubular helical chain. Second, when the orange-yellow crystals of 4 were immersed in the mother liquor at room temperature, vivid bright yellow crystals of {[Zn(3-bpdb)(n-BuO-ip)]•2H 2 O} n (5) with a 2D terrace layered structure and bright yellow crystals of {[Zn(3-bpdb)(n-BuO-ip)(H 2 O)]•1.5H 2 O} n (6) with a single-layered 2D (4,4) grid network were obtained on the 8th and 20th days by single-crystalto-single-crystal (SCSC) phase transformation, respectively. These structural transformations were thoroughly studied by powder Xray diffraction (PXRD) analysis and field-emission scanning electron microscopy (FE-SEM) along with single-crystal X-ray diffraction. In order to clarify the structure control factors in this series of CPs, similar reactions with 1−4 were continuously carried out, except that Zn(NO 3 ) 2 •6H 2 O was replaced by Co(NO 3 ) 2 •6H 2 O, and four Co(II)-based CPs formulated as [Co(3-bpdb)(MeOip)] n (7), [Co(3-bpdb)(EtO-ip)] n (8), {[Co(3-bpdb)(n-PrO-ip)]•H 2 O} n (9), and [Co(3-bpdb)(n-BuO-ip)] n (10) were purposefully constructed. The whole structures of 7−10 are isostructural with 1−3 and 5, respectively. The present results reveal that substitutions of isophthalic acid ligands with different lengths exert significant effects on the architecture of the CPs. Besides, the fluorescent properties of 1−6 were also investigated. The magnetic measurements indicate that CP 7 exhibits weak antiferromagnetic interactions, and CPs 8−10 exhibit weak ferromagnetic interactions within the binuclear (Co II ) 2 units. Magnetostructure relationships were investigated as well.

SCSC Transformation and Post-Synthesis Modification of MOFs with Proton Conduction and Ratiometric Fluorescence-Sensing Properties

“…Details of the holes are shown in Video 1. The structure of 1 is isomorphic to our previously reported case of Zn–MOF …”

“…The structure of 1 is isomorphic to our previously reported case of Zn−MOF. 31 As estimated by the PLATON program, the accessible void volume in 1 is 9.6%; this is possibly occupied by few solvent molecules; however, the solvent molecules cannot be accurately identified. According to the thermogravimetric measurement, almost no weight loss occurred before 350 °C, indicating that the solvent molecules in the skeleton were negligible (Figure S2).…”

Solvent-oriented structural diversity, sequential SCSC and low-temperature transformation in Cd-coordination polymers: unique turn-on–off sensing of Fe3+

“…As mentioned earlier, the flexible conformation of n-BuO-H 2 ip ligands and 3-bpdb is advantageous for the proposed strategy as they can easily respond to the solvent environment. As shown in previous work, 34,35 the presence of alkoxy groups exhibits a certain degree of structural flexibility in the rigid backbone, and increasing the chain length increases the possibility of flexible conformation, resulting in the structural diversity of CPs. The alkoxy chain, like a tadpole, swims around under the stimulation of different solvents to give rise to a number of conformations that direct the selfassembly of CPs (Fig.…”

In Situ Conversion of Ligand to a Coordination Polymer via a Core@Shell Crystal: A Multi-Step Phase-Dependent Structural Transformation

“…Synthesis of [Cd(3,3′-pytz)(H 2 O) 2 (ClO 4 ) 2 ] n (3). Our analysis shows that single crystals of compounds 1 and 2 were unstable after extraction from the mother solvent at room temperature and after 5 months completely transformed into purplish-red powder of compound 3.…”