The elusive γ phase of trimesic acid (TMA, 1,3,5-benzenetricarboxylic acid) has been prepared by recrystallization of commercial α-TMA in acetic acid. This process yields a modified γ-TMA phase that contains guest acetic acid solvent molecules with an approximate stoichiometry of γ-TMA·1HAc. According to 1H NMR and crystal structure determination, guest molecules are located both in the channels and in relatively isolated cavities. Despite the constricted connection between channels and cavities, solvent guest molecules are easily removed, even at room temperature, yielding guest-free γ-TMA. This process is reversible, since pristine γ-TMA can reabsorb acetic acid vapor at room temperature, yielding again γ-TMA·1HAc. Conversely, γ-TMA only adsorbs negligible amounts of N2 at 77 K or CO2 at 273 K, denoting that the guest–adsorbent interaction is a key factor governing adsorption.

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The crystal structure of three new complexes of stoichiometry [Cu(pOHBz)2(dPy)2] (pOHBz: p‐hydroxybenzoate, dPy= 4‐phenylpyridine, 4‐benzylpyridine, 3‐phenylpyridine) and its comparison with the previously reported [Cu(pOHBz)2(Py)2] (1) indicate that the nature and position of the pyridine substituent determines different roles for the phenol group from the pOHBz ligand and, consequently, the coordination number and geometry of Cu(II) centers. Results herein reported show the versatility of the pOHBz ligand towards the coordination of Cu(II). Different carboxylate bonding modes are also observed: monodentate, bidentate chelating or bidentate bridge. Besides, this governs the different roles of the phenol group of the pOHBz ligand: founding of supramolecular hydrogen‐bond based network or direct bonding to the copper cation, yielding 2D coordination polymers.

Cu(m-MeCO2)2(4-Bzpy)]2 (4-Bzpy ¼ 4-benzylpyridine) has been synthesized by reaction of [Cu(m-MeCO2)2(H2O)]2 with 4-Bzpy in methanol at room temperature. The compound was characterized by Elemental Analysis, ATR-FTIR and X-ray Powder Diffraction. The molecular structure was determined by single crystal X-ray diffraction analysis at 100 K and 303 K. The compound consists of binuclear units where both Cu(II) atoms are linked by four syn-syn carboxylate bridges, showing a paddle-wheel unit. The role of CeH/O hydrogen bonds in the establishment of its supramolecular network is discussed, comparing the resulting structural parameters at the two different temperatures. Finally, the thermal variation of XpT for compound 1 has also been studied, suggesting an antiferromagnetic Cu/Cu interaction (J¼ 311 cm 1), which agrees with the presence of four m-kO-kO0 carboxylates bridging the metallic centers in the binuclear complex.

Conventional organic solvents are the preferred media to prepare and crystallize metallorganic materials, since the wide diversity of organic solvents allows the control of solubility parameters and precipitation kinetics. However, they are the largest waste input in fine chemical synthesis; and moreover, in the processing of materials with ester containing groups, which have a significant tendency to hydrolysis, the use of organic solvents can be too aggressive to keep the structure of labile molecules. In this context, milder methods to prepare crystalline metallorganic derivatives of triflusal (HTrf), a drug bearing an ester group, are here described. HTrf molecule itself and its derivatives have important applications in the pharmaceutical industry. In this work, copper triflusalate complexes and derived pyridine adducts are prepared via an environmentally friendly supercritical CO2 method, preserving the ester group from hydrolysis. For comparison, some intricate conventional solvent liquid methods are also envisaged. Products are fully characterized in regard of composition, structure and magnetic properties.