Crystal Structures and Spectroscopic Properties of Metal–Organic Frameworks Based on Rigid Ligands with Flexible Functional Groups

Abstract

Two rigid linear ligands with alkoxy functional groups (L1 = 4,4′-(2,5-dimethoxy-1,4-phenylene) dipyridine; L2 = 4,4′-(2,5-diethoxy-1,4-phenylene) dipyridine) incorporating carboxyl-containing auxiliary ligands (isophthalic acid = H2IPA; terephthalic acid = H2TPA; biphenyl-4,4′-dicarboxylate = H2BPDC) have been adopted to build a series of complexes with M(II) (M = Zn, Co, Cd) under solvothermal conditions. The formula of these complexes are {[Zn(L1)(IPA)]} n (1), {[Zn(L1)(TPA)]·DMF} n (2), {[Co(L1)(TPA)(H2O)2]·2DMF} n (3), {[Cd(L1)(TPA)(H2O)2]·2DMF} n (4), and {[Co(L2)(BPDC)]·0.5H2O} n (5). Five complexes have been characterized by elemental analysis, infrared spectroscopy, powder X-ray diffraction and thermogravimetry measurements. Topological analyses reveal that complex 2 is a 6-connected pcu net with point symbol {412·63}, while complex 5 is a 6-connected rob net with point symbol {48·68·8}, the other complexes 1, 3, and 4 can be simplified as 4-connected sql nets with point symbol {44.62}. Complexes 1, 3, and 4 are 2D layer motifs, 2 and 5 are both 2-fold interpenetrating 3D frameworks. The optical absorption spectra of 3 and 5 indicate the nature of semiconductivity. The strong fluorescence emissions and long emission lifetimes of 1, 2, and 4 display that they are promising phosphorescent materials.

Morphological and Structural Evolutions of Metal–Organic Framework Particles from Amorphous Spheres to Crystalline Hexagonal Rods

“…Even though IPAl inkers in addition to BDC linkers were present in MOF particles,M OF particles constructed from the dominant contribution of BDC linkers, such as inflated hexagonal rods,a ngulated ovals,a nd ovals, were highly crystalline materials that had athree-dimensional hexagonal structure similar to that of pure In-MIL-68. Ap lausible reason for the structural transition from crystalline to amorphous can be found from the different degree of disorders of the two organic linkers.Many possible disorders of IPAlinkers within the MOF structure likely resulted in the formation of amorphous materials during the rapid synthesis of MOF particles.S everal crystalline MOFs containing IPA linkers have been reported; [7] however,t hese crystalline MOFs were usually constructed slowly to ensure sufficient time for the construction of aw ell-ordered crystalline structure. Ap lausible reason for the structural transition from crystalline to amorphous can be found from the different degree of disorders of the two organic linkers.Many possible disorders of IPAlinkers within the MOF structure likely resulted in the formation of amorphous materials during the rapid synthesis of MOF particles.S everal crystalline MOFs containing IPA linkers have been reported; [7] however,t hese crystalline MOFs were usually constructed slowly to ensure sufficient time for the construction of aw ell-ordered crystalline structure.…”

Crystal structure of poly[aqua-(2,2′-bipyridine-κN,N′)-(μ4-5,5′-(hexane-1,6-diyl)-bis(oxy)diisophthalato κ8 O 1,O 2:O 3,O 4:O 5,O 6:O 7,O 8)manganese(II)], C21H

“…Metal-organic frameworks (MOFs) with boundless network structures have been a vibrant research field and aroused considerable attention from both academia and industry [1][2][3][4][5][6][7]. Theoretical predictions and network-based methods to regulate the network topology and geometries have been done to generate serviceable functional frameworks [8].…”

Morphological and Structural Evolutions of Metal–Organic Framework Particles from Amorphous Spheres to Crystalline Hexagonal Rods

“…However,s pherical particles (Figure 3a'), which contained ar elatively high proportion of IPAl inkers,h ad amorphous characteristic similar to particles produced from pure IPA linkers.B ased on these results,w ec oncluded that highly crystalline MOF particles were produced when the contribution of BDC linkers to MOF particles increased, while amorphous MOF particles were obtained when the contribution of IPAl inkers to MOF particles increased. Ap lausible reason for the structural transition from crystalline to amorphous can be found from the different degree of disorders of the two organic linkers.Many possible disorders of IPAlinkers within the MOF structure likely resulted in the formation of amorphous materials during the rapid synthesis of MOF particles.S everal crystalline MOFs containing IPA linkers have been reported; [7] however,t hese crystalline MOFs were usually constructed slowly to ensure sufficient time for the construction of aw ell-ordered crystalline structure.…”