Selected recent examples of coordination polymers (CPs) or metal-organic frameworks (MOFs) constructed from different multifunctional carboxylic acids with phenyl-pyridine or biphenyl cores have been discussed. Despite being still little explored in crystal engineering research, such types of semi-rigid, thermally stable, multifunctional and versatile carboxylic acid building blocks have become very promising toward the hydrothermal synthesis of metal-organic architectures possessing distinct structural features, topologies, and functional properties. Thus, the main aim of this mini-review has been to motivate further research toward the synthesis and application of coordination polymers assembled from polycarboxylic acids with phenyl-pyridine or biphenyl cores. The importance of different reaction parameters and hydrothermal conditions on the generation and structural types of CPs or MOFs has also been highlighted. The influence of the type of main di- or tricarboxylate ligand, nature of metal node, stoichiometry and molar ratio of reagents, temperature, and presence of auxiliary ligands or templates has been showcased. Selected examples of highly porous or luminescent CPs, compounds with unusual magnetic properties, and frameworks for selective sensing applications have been described.

Two multifunctional, ether-bridged tricarboxylic acids, 2-(4-carboxylphenoxy)terephthalic acid (H₃cpta) and 2-(3,5-dicarboxylatobenzyloxy)benzoic acid (H₃dbba), were used as unexplored and highly versatile building blocks for the hydrothermal generation of a novel series of cadmium(II) metal–organic architectures. These were formulated as [Cd(μ-Hcpta)(phen)(py)]_n (1), {[Cd₃(μ₅-cpta)₂(phen)₃]·8H₂O}_n (2), {[Cd₃(μ₅-cpta)₂(2,2′-bipy)₃]·6H₂O}_n (3), {[Cd(μ₃-cpta)(Hbpa)]·2H₂O}_n (4), {[Cd₆(μ₄-cpta)₂(μ₆-cpta)₂(H₂biim)₂(H₂O)₆]·5H₂O}_n (5), [Cd₃(μ₄-cpta)₂(μ-prz)(H₂O)₄]_n (6), {[Cd₃(μ₄-dbba)₂(phen)₃]·H₂O}_n (7), and {[Cd₃(μ₃-dbba)₂(2,2′-bipy)₃(H₂O)₃]·2H₂O}_n (8) on the basis of single-crystal X-ray diffraction, elemental analysis, FTIR, PXRD, and TGA data. Products 1–8 were assembled in the presence of N-donor crystallization mediators selected from pyridine (py), 1,10-phenanthroline (phen), 2,2′-bipyridine (2,2′-bipy), bis(4-pyridyl)amine (bpa), 2,2′-biimidazole (H₂biim), or piperazine (prz). The nature of the crystallization mediator and/or the type of principal tricarboxylate building block have a significant effect on the structural diversity, dimensionality, and topology of the resulting cadmium-organic architectures. These span from 1D (1, 8) and 2D (7) coordination polymers to 3D metal–organic frameworks (2–6) with intricate topologies (3,4,5T64 in 2 and 3, utp (10³)-d in 4, 3,4,4T9 in 6) that also include unprecedented types in 5 and 7. Besides, MOF 6 features a 3D + 3D two-fold interpenetrated framework. Luminescent and photocatalytic properties of selected materials were investigated, showing that coordination polymer 7 is a promising photocatalyst for the UV-light-driven degradation of methylene blue as a model organic dye pollutant. Moreover, products 7 and 8 are the first examples of structurally characterized coordination compounds derived from H₃dbba.

A Lewis acid promoted tandem reaction of epoxide rearrangement and intramolecular [3+2] cycloaddition reaction of cyclopropanes with carbonyls formed by epoxide rearrangement in situ, which were obtained with difficulty by a general method, is reported. A wide variety of fused- and spiro-oxa-[n.2.1] skeletons could be efficiently constructed.