Coordination Polymers Based on Highly Emissive Ligands: Synthesis and Functional Properties

Coordination polymers are constructed from metal ions and bridging ligands, linking them into solid-state structures extending in one (1D), two (2D) or three dimensions (3D). Two- and three-dimensional coordination polymers with potential voids are often referred to as metal-organic frameworks (MOFs) or porous coordination polymers. Luminescence is an important property of coordination polymers, often playing a key role in their applications. Photophysical properties of the coordination polymers can be associated with intraligand, metal-centered, guest-centered, metal-to-ligand and ligand-to-metal electron transitions. In recent years, a rapid growth of publications devoted to luminescent or fluorescent coordination polymers can be observed. In this review the use of fluorescent ligands, namely, 4,4'-stilbenedicarboxylic acid, 1,3,4-oxadiazole, thiazole, 2,1,3-benzothiadiazole, terpyridine and carbazole derivatives, naphthalene diimides, 4,4',4''-nitrilotribenzoic acid, ruthenium(II) and iridium(III) complexes, boron-dipyrromethene (BODIPY) derivatives, porphyrins, for the construction of coordination polymers are surveyed. Applications of such coordination polymers based on their photophysical properties will be discussed. The review covers the literature published before April 2020.

Structural and transport properties of neutral radical crystals of CoIII(tmp)(CN)2 (tmp = 5,10,15,20-tetramethylporphyrinato) and the CN-bridged polymer [CoIII(tmp)(CN)]n

An axially ligated Co(tmp) (tmp = 5,10,15,20-tetramethylporphyrinato) anion, [Co^III(tmp)(CN)₂]^-, has been prepared and subjected to electrochemical oxidation to obtain the open shell tmp π-ligand. With acetone as the solvent, solvent-free neutral radical crystals of Co^III(tmp)(CN)₂ are obtained, whereas solvent-inclusive crystals of Co^III(tmp)(CN)₂·2CH₃CN are obtained with CH₃CN as the solvent. In both crystals, the open shell tmp ring deforms into a ruffled form, which makes the π-π interactions in the crystal weak. Thus, the electrical conductivity is low, and the crystals behave as semiconductors with a room temperature resistivity of 10⁶ Ω cm and an activation energy of about 0.3 eV. When the solvent is acetone, non-oxidized crystals of the CN-bridged polymer {[Co^III(tmp)(CN)](acetone)}_n are obtained as a byproduct. The closed shell tmp ring deforms into a ruffled form, and there π-π interactions in the crystal are negligible. The room temperature resistivity is rather high at about 10⁸ Ω cm.

Porphyrinic metal–organic frameworks from custom-designed porphyrins

This paper highlights porphyrinic metal–organic frameworks (porph-MOFs) assembled from metal ions and custom-designed porphyrins: pyridyl-based, carboxyphenyl-based porphyrins and other custom-designed porphyrins.

Heterogeneous catalytic properties of unprecedented μ-O-[FeTCPP]2 dimers (H2TCPP = meso-tetra(4-carboxyphenyl)porphyrin): an unusual superhyperfine EPR structure

Solvent accessible volume of the active catalyst μ-O-[FeTCPP]₂·nDMF dimer revealing an unusual superhyperfine EPR structure.

Multiply biphenyl substituted zinc(II) porphyrin and phthalocyanine as components for molecular materials

The preparation and physico-chemical characteristics of zinc(II) porphyrin and phthalocyanine derivatives with biphenyl units are reported. These compounds have been prepared as components for molecular electronics systems and rotor-based molecular machines, where the biphenyl units can act as paddles because they are oriented quasi-perpendicularly to the plane of the aromatic macrocycles which would be coordianted through the transition metal ion by an axial ligand. The minimalist design along with the absence of solubilizing groups leads to a low solubility of the compounds in organic solvents; the phthalocyanines is only sparingly soluble while the porphyrin is more easily manipulated, but in any case the concentration of both compounds is sufficient for surface deposition. The luminescence of the compounds is characteristic of the central unit, although it is clear in the absorption spectra that the phthalocyanine derivative has a particularly strong tendency to aggregate non-specifically. The porphyrin forms microcrystals while the phthalocyanines which bears eight biphenyl units forms amorphous aggregates from 1,2-dichlorobenzene reminiscent of glasses of other biphenyl derivatives, which is interesting for the preparation of amorphous materials for optics applications.

MALDI-TOFMS analysis of coordination and organometallic complexes: a nic(h)e area to work in

A mini-review of the characterisation of metal-containing compounds by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) is presented. Organometallic and coordination compounds have many varied applications, most notably in industrial catalytic processes and also in the electronics and healthcare sectors. In general, the compounds discussed, be they small or large molecules, have a high percentage metal content, rather than simply containing 'a metal atom'. A brief history of the field is given, but the main scope over the last 5 years is covered in some detail. How MALDI-TOFMS compliments electrospray for metal-containing compounds is highlighted. Perspectives on recent advances, such as solvent-free and air/moisture-sensitive sample preparation, and potential future challenges and developments, such as nanomaterials and metallodrug/metallometabolite imaging, are given.