Effect of the Pyridine Substituent on the Role of the Phenol Functional Group in [Cu(pOHBz)₂(dPy)₂] Complexes (pOHBz: p‐Hydroxybenzoate, dPy= 4‐Phenylpyridine, 4‐Benzylpyridine, 3‐Phenylpyridine).

Abstract

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.

Modulatingp-hydroxycinnamate behavior as a ditopic linker or photoacid in copper(ii) complexes with an auxiliary pyridine ligand

“…Furthermore, the free space in 3 is much larger than the reported 4.2% for the [Cu(µ-pOHBz) 2 (4-Bzpy) 2 ] n polymer. 14 However, this result shows that not only a longer spacer between the phenol and the carboxylate functional groups is required for increasing the free space, but also functional groups that prevent the stacking of the layers from obstructing the cavities.…”

“…All these distances and angles are in good agreement with related Cu(II) carboxylate-pyridine compounds. 14,44,45 Relevant distances and angles are summarized in Table 1.…”

“…This supramolecular arrangement is similar to the one found in [Cu(µ-pOHBz) 2 (4-Phpy) 2 ] and [Cu(µ-pOHBz) 2 (4-Bzpy) 2 ] n . 14 This allows the formation of H-bonds that hold the layers together in a 3D supramolecular structure. In 2, the carbonyl group of 4-Acpy is responsible for these interaction, forming an H-bond with the hydrogen on the para position of the neighboring 4-Acpy ligand.…”

“…These previous results clearly suggest the potential of organic-inorganic building blocks with peripheral phenol groups for the preparation of both supramolecular and covalent networks. 14 Some of these compounds show incipient porosity. Hence, in light of the obtained results it was suggested that using ligands with longer distances between the carboxylate and the phenol functionalities could result in an increase in the overall empty space, an already successful strategy.…”

Reactivity of homoleptic and heteroleptic core paddle wheel Cu(II) compounds

“…Recently, we have been studying the role of carboxylic acids in the structural arrangement. In this sense, reactions with 4-hydroxybenzoic acid (HpOHBz), (E)-3-(4-hydroxyphenyl)-2-propenoic acid (para-hydroxycinnamic acid, HpOHcinn) and 1,3-benzodioxole-5-carboxylic acid (Piperonylic acid, HPip) with Cu(II) [17][18][19][20], Zn(II) [21] and Cd(II) [21] have already been studied.…”