Silver–pyrazole complexes as hybrid multifunctional materials with metallomesogenic and photoluminescent behaviour

Abstract

New pyridine-functionalised pyrazole compounds [Hpz(R(n)py)] (R(n) = C(6)H(4)OC(n)H(2n+1); n = 12, 14, 16, 18; 1-4) and their corresponding silver complexes [Ag(Hpz(R(n)py))(2)][A] ([A] = NO(3)(-), BF(4)(-); ) have been synthesised and characterised. All of them, with the exception of 1, are liquid crystal materials exhibiting monotropic or enantiotropic SmA mesophases, in contrast to the non-mesomorphic related R(n)-monosubstituted compounds. Because the molecular shape is a factor determinant in the organisation of molecules in the liquid crystal phase, we were interested in solving the crystal structure of representative examples of the mentioned compounds, such as 1 and 6. So, the X-ray crystal structure of [Hpz(R(12)py)] 1 shows the presence of dimeric units through N-H···N hydrogen bonds, which conform to an elongated molecular shape containing a double chain length. On the other hand, the structure of [Ag(Hpz(R(14)py))(2)][NO(3)] 6 also evidenced Ag-Ag bonded dimers from 'U'-shaped cationic entities. These dimers exhibit four chains, two by two alternated, so giving rise to a longer molecular length. Of particular interest was to observe that in both structures, the dimers are layer-like packed, their lamellar structures being related to that of the mesophases found in both kinds of compounds. Furthermore, the analysis of the optical data of the compounds 2 and 4 and the silver compounds 5, 6, 9 and 10 as representative examples pointed out their luminescent behaviour as well as their good ability to act as fluorescent probes for Zn(2+), Cu(2+) and Ag(+). An increase in the fluorescence quantum yields is observed in the final complexes produced in the titrations, this fact being specially notable when 9 was used as the starting compound.

Synthesis and antimicrobial evaluation of a pyrazoline-pyridine silver(I) complex: DNA-interaction and anti-biofilm activity

“…The lengths of Ag-N bond range from 2.294 to 2.454 A ˚and the bite angles N-Ag-N are equal * 71°. These B3LYP/ LANL2DZ calculated values of distances and angles around the Ag atom are in good agreement with experimental values reported for similar silver(I) complexes (Ovejero et al 2013;Cifuentes-Vaca et al 2019).…”

An overview of phosphorescent metallomesogens based on platinum and iridium

“…[62][63][64][65][66] Pt complexes with bidentate N^N ligands Bidentate, anionic N^N ligands derived from, for example, 2-(pyrazol-3-yl)pyridines or 2-(1,2,3-triazol-4-yl)pyridine, can lead to highly luminescent cyclometallated platinum complexes, 67 with the azido nitrogen increasing the ligand field by virtue of being a strong -donor. Pyrazolylfunctionalised pyridines turn out to be especially popular, [68][69][70][71][72][73][74][75] so that complex 18a (Figure 13) with tris(alkoxy)phenyl groups, prepared by Hsu et al, 68 exhibited columnar mesophases with very wide temperature ranges. The melting point had an obvious dependence on chain length whereas the clearing temperature did not.…”

Two 1D Silver(I) Coordination Polymers with 1,3‐Bis(4‐pyridyl) propane and Aromatic Carboxylate Anions: Synthesis, Structure and Photocatalytic Behavior

“…[1,2,3] In fact, such coordination complexes find potential applications in different fields like medicine, electronics, catalysis, photocatalysis and technology. [4][5][6][7][8][9] CPs of silver ions with appropriate NÀ and OÀ donor ligands (like bipyridine, bicarboxylate species, etc.) are presently very common, and the strong proclivity of Ag(I) for linear coordination geometry, allows the construction of simple, one-dimensional motifs.…”