Zn(II) and Cd(II) Metal–Organic Frameworks with Azine-Functionalized Pores: Crystal Structures, Photoluminescence, Solvent Exchange, and Molecular Simulations of Carbon Dioxide Binding Sites

• Published in: Crystal growth & design 2023-05, Vol.23 (5), p.3171-3185
• Main Authors: Lozovan, Vasile, Kravtsov, Victor Ch, Chumakov, Yurii M., Costriucova, Natalia V., Siminel, Nikita, Petuhov, Oleg, Vlase, Titus, Vlase, Gabriela, Barba, Alic, Fonari, Marina S.
• Format: Article
• Language: English
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.2c01345

Four neutral metal–organic frameworks (MOFs) {[Zn­(bpdc)­(3-bpmhz)]·1.5­(dmf)} n MRT-1 (1), {[Zn­(bpdc)­(3-bpmhz)]·(dmf)·0.5­(Py)} n MRT-2 (2), {[Zn­(bpdc)­(4-bpmhz)]­(MeOH)·0.5­(H2O)} n MRT-3 (3), and {[Cd­(bpdc)­(bda4bPy)]·2.5­(dmf)} n MRT-4 (4) (where MRT stands for the Moldova Research Team), along with a one-dimensional coordination polymer {[Zn­(Hbpdc)2(3-bphz)­(MeOH)2]·2­(dmf)} n (5), a binuclear complex [Cd2(bpdc)2(3-bpmhz)­(H2O)6] (6), and a two-dimensional coordination polymer {[Cd­(bpdc)­(dmso)­(H2O)]·0.25­(H2bpdc)} n (7), were obtained from blends of 4,4′-biphenyldicarboxylic acid (H2bpdc) with 1,2-bis­(1-(pyridin-3-yl)­ethylidene)­hydrazine (3-bpmhz), 1,2-bis­(pyridin-3-ylmethylene)­hydrazine (3-bphz), 1,2-bis­(1-(pyridin-4-yl)­ethylidene)­hydrazine (4-bpmhz), or N 1,N 4-bis­(pyridin-4-ylmethylene)-benzene-1,4-diamine (bda4bPy). MOFs 1 and 2 are supramolecular isomers. MOF 1 is built on a single tetrahedral Zn­(II) atom giving rise to a diamondoid (dia) coordination network with threefold interpenetration. MOFs 2–4 represent a reticular series of primitive cubic (pcu) networks that originated from [M2(CO2)4] (M = Zn and Cd) secondary building units where the metal-carboxylate coordination layers are interlinked by azine double pillars. MOFs 2 and 4 reveal the twofold interpenetrations, while MOF 3 reveals threefold interpenetration. Thermal analysis of MOFs 1–4 carried out in the air and nitrogen atmospheres indicated their thermal stability. MOFs 1 and 4 had the solvent-accessible volumes of 30.1 and 43.7%, respectively. MOF 4 demonstrated an efficient solvent exchange with the nitrobenzene (nb) capture registered by spectroscopic methods and confirmed by X-ray single-crystal studies for the crystal {[Cd­(bpdc)­(bda4bPy)]·1.5­(nb)} n (4-nb). All compounds reveal ligand-based photoluminescence properties registered in the blue and green regions of the visible spectrum for 1–3 and 5–7. The most porous MOF 4 emitted very near to the standard white light and in the orange region when loaded with nb. The symmetry-adapted perturbation theory showed advantages of azine-functionalized pores in the studied MOFs for efficient capture of CO2 molecules on the pores’ walls.