Co(II) coordination polymers exhibiting reversible structural transformation and color change: A comparative analysis with Ni(II) analogue

Metal and Ligand Effect on the Structural Diversity of Divalent Coordination Polymers with Mixed Ligands: Evaluation for Photodegradation

Eight coordination polymers constructed from divalent metal salts, N,N^'-bis(pyridin-3-ylmethyl)terephthalamide (L), and various dicarboxylic acids are reported, affording [Co(L)(5-ter-IPA)(H₂O)₂]_n (5-tert-H₂IPA = 5-tert-butylisophthalic acid), 1, {[Co(L)(5-NO₂-IPA)]⋅2H₂O}_n (5-NO₂-H₂IPA = 5-nitroisophthalic acid), 2, {[Co(L)_0.5(5-NH₂-IPA)]⋅MeOH}_n (5-NH₂-H₂IPA = 5-aminoisophthalic acid), 3, {[Co(L)(MBA)]⋅2H₂O}_n (H₂MBA = diphenylmethane-4,4'-dicarboxylic acid), 4, {[Co(L)(SDA)]⋅H₂O}_n (H₂SDA = 4,4-sulfonyldibenzoic acid), 5, {[Co₂(L)₂(1,4-NDC)₂(H₂O)₂]⋅5H₂O}_n (1,4-H₂NDC = naphthalene-1,4-dicarboxylic acid), 6, {[Cd(L)(1,4-NDC)(H₂O)]⋅2H₂O}_n, 7, and {[Zn₂(L)₂(1,4-NDC)₂]⋅2H₂O}_n, 8, which were structurally characterized by using single-crystal X-ray diffraction. The structural types of 1-8 are subject to the metal and ligand identities, showing a 2D layer with the hcb, a 3D framework with the pcu, a 2D layer with the sql, a polycatenation of 2-fold interpenetrated 2D layer with the sql, a 2-fold interpenetrated 2D layer with the 2,6L1, a 3D framework with the cds, a 2D layer with the 2,4L1, and a 2D layer with the (10²⋅12)(10)₂(4⋅10⋅12⁴)(4) topologies, respectively. The investigation on the photodegradation of methylene blue (MB) by using complexes 1-3 reveals that the degradation efficiency may increase with increasing surface areas.

Structural Transformations in Cobalt(II) Coordination Polymers Constructed from Flexible N,N’-Bis(3-pyridylmethyl)sebacoamide and benzene-1,3,5-tricarboxylic acid

Hydro(solvo)thermal reactions of cobalt(II) salts, N,N’-bis(3-pyridylmethyl)sebacoamide (L) and benzene-1,3,5-tricarboxylic acid (1,3,5-H3BTC) in water afforded {[Co(L)(1,3,5-HBTC)]·H2O}n, 1, and {[Co2(L)2(1,3,5-HBTC)2(H2O)4]·9H2O}n, 2, whereas in MeOH and MeOH/H2O gave {[Co3(L)(1,3,5-BTC)2(CH3OH)5]·5CH3OH}n, 3, and {[Co1.5(L)0.5(1,3,5-BTC)(CH3OH)(H2O)3]·H2O}n, 4,...

Zn(ii) and Co(ii) coordination polymers based on semi-rigid bis-pyridyl-bis-amide and angular dicarboxylate ligands: synthesis, structures and properties

Hydro(solvo)thermal reactions of N,N′-di(3-methylpyridyl)oxalamide (L1) and N,N′-di(4-methylpyridyl)oxalamide (L2) with angular dicarboxylic acids and metal salts afforded six new coordination polymers showing interesting properties.

Exploring Reversible Thermochromic Behavior in a Rare Ni(II)-MOF System

Thermochromic metal-organic frameworks (MOFs) are promising functional materials for a wide range of applications due to their ability to exhibit color variation under external temperature stimuli, yet the development of them with high cyclability and efficient regeneration processes remains challenging. Here, presented is a rare example of an ultrastable Ni(II)-MOF exhibiting an unprecedented reversible four-step color change between two complementary colors in a wide temperature range, which could be repeated for at least 500 cycles without losing crystallinity and thermochromic performance. Notably, the regeneration can be achieved within 1 min by simply letting the crystals cool naturally in the air, facilitated by the unique nature of the channels' inner surface. The reversible thermochromic behavior is owing to a series of reversible crystal structure changes with temperature, including the stepwise dehydration/rehydration process, and structural changes. This work facilitates the future development of more MOF-based reversible thermochromic materials with excellent performance and improved practical applicability.

Cobalt(ii) coordination polymers constructed from bis(N-pyrid-3-ylmethyl)adipoamide and polycarboxylic acids: reversible structural transformation upon proton delivery and removal

The reversible structural transformation upon proton delivery and removal in Co(ii) coordination polymers can be ascribed to the various bonding modes and the flexibility of the spacer ligands.

A Pair of CoII Supramolecular Isomers Based on Flexible Bis-Pyridyl-Bis-Amide and Angular Dicarboxylate Ligands

Thermal reactions of cobalt(II) salts with flexible N,N′-bis(pyrid-3-ylmethyl)adipoamide (L) and angular 4,4′-sulfonyldibenzoic acid (H₂SDA) in H₂O and CH₃OH afforded a pair of supramolecular isomers: [Co₂(L)(SDA)₂], 1, and [Co₂(L)(SDA)₂]⋅CH₃OH⋅H₂O, 2. The structure of complex 1 can be simplified as a one-dimensional (1D) looped chain with L ligands penetrating into the middles of squares, forming a new type of self-catenated net with the (4²⋅5⁴)(4)₂(5)₂ topology, whereas complex 2 displays a 2-fold interpenetrated 2D net with the rare (4²⋅6⁸⋅8⋅10⁴)(4)₂-2,6L1 topology. While both complexes 1 and 2 display antiferromagnetism with strong spin-orbital coupling, the antiferromagnetism of 2 is accompanied by a cross-over behavior and probably a spin canting phenomenon.

p-Xylylenediamine derived ligands as flexible connectors in the design of porous coordination polymers

Flexible tetrabenzoate xylylenediamine-based ligands form both discrete and polymeric assemblies, the latter displaying the targeted amine-lined pore spaces.

Crystal-to-crystal transformation and linker exchange in Cd(ii) coordination polymers based on flexible bis-pyridyl-bis-amide and 1,4-naphthalenedicarboxylate

Solvothermal reactions of Cd(ii) salts and naphthalene-1,4-dicarboxylic acid with bis(N-pyrid-3-ylmethyl)adipoamide and bis(N-pyrid-3-ylmethyl)suberoamide yield three Cd(ii) coordination polymers that undergo reversible crystal-to-crystal transformation and linker exchange.