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

Abstract

The reaction of copper(ii) acetate monohydrate with p-hydroxycinnamic acid (HpOHcinn) and different pyridine derivatives (4-tert-butylpyridine, 4-tBupy; 4-acetylpyridine, 4-Acpy; 3-phenylpyridine, 3-Phpy; 4-phenylpyridine, 4-Phpy) was essayed in methanol solvent at room temperature. The crystal structures of the resulting compounds were elucidated. Their analysis shows that the choice of pyridine ligands determines different coordination modes of the pOHcinn ligand and the Cu(ii) coordination, nuclearity and geometry. The pOHcinn acts as a monodentate carboxylate ligand in combination with 4-tBupy or 4-Phpy, yielding monomers and dimers, associated by hydrogen bonds into supramolecular networks in which the phenol group plays a key role. Conversely, in combination with 4-Acpy or 3-Phpy, the phenol group coordinates directly to the Cu(ii), acting as a ditopic ligand and yielding 2D coordination polymers. The compound containing 3-Phpy shows interesting MeOH-H2O reversible exchange behavior. Not only has the pyridine auxiliary ligand had a tremendous effect on the coordination mode of pOHcinn, but also its reactivity is influenced. Particularly, in the case of the compound containing 4-Phpy, it undergoes a photoinduced process, in which the phenol group deprotonates and coordinates to Cu(ii) as a phenoxy ligand. This yields a coordination polymer in which two different dimers alternate, bridged by the resulting pOcinn ligand. The magneto-structural correlation of this compound is also discussed.

Exploring the reactivity of α-Acetamidocinnamic acid and 4-Phenylpyridine with Zn(II) and Cd(II)

“…[Cu(4-Phpy)2(µ-p-OHCA)(p-OHCA)]2 and [Cu(µ-p-OHCA)2(4-Acpy)2]n. Interestingly, the compounds containing 4-Phpy undergo a photoinduced process [33].…”

Structure, Optical and Magnetic Properties of Two Isomeric 2-Bromomethylpyridine Cu(II) Complexes [Cu(C6H9NBr)2(NO3)2] with Very Different Binding Motives

“…Additionally, the nature of the ligand combined with the h ard and s oft a cids-and b ases principle (HSAB) help in taming the quite flexible geometries of many 3D transition metals. Thus, using the very simple synthesis approach of mixing ligands and transition metal precursors in solution and precipitating or crystallizing the products, defined materials with interesting catalytic [ 17 , 18 , 19 , 20 , 21 ], electrochemical [ 21 , 22 ], magnetic [ 23 , 24 , 25 ], photochemical [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ], and photophysical properties [ 30 , 31 , 32 , 33 , 34 , 35 ] have been obtained in good yields.…”

Construction of Zn(II) Linear Trinuclear Secondary Building Units from A Coordination Polymer Based on α-Acetamidocinnamic Acid and 4-Phenylpyridine

“…Recently, our group has been studying the reactivity of cinnamic acid derivative ligands towards Cu(II) [ 41 ], Zn(II), and Cd(II) [ 42 ] metal nodes. Specifically, the α-acetamidocinnamic acid (HACA), which incorporates an additional acetamide group in the cinnamic acid structure, has been examined in combination with the d 10 metal ions Zn(II) and Cd(II) yielding isostructural monomeric complexes ([M(ACA) 2 (H 2 O) 2 ], M = Zn(II) or Cd(II)), whose reactivity in presence of the 4-phenylpyridine ligand show a different behavior between Zn(II) and Cd(II), yielding a monomeric [Zn(4-Phpy) 2 (ACA) 2 (H 2 O) 2 ]·3H 2 O and a dimeric [Cd(4-Phpy) 2 (μ-ACA)(ACA)] 2 ·2EtOH complexes.…”