Copper(I) Cyanide Networks:  Synthesis, Luminescence Behavior and Thermal Analysis. Part 1. Diimine Ligands

Abstract

Metal-organic networks of CuCN with diimines (L) = pyrazine (Pyz), 2-aminopyrazine (PyzNH(2)), quinoxaline (Qox), phenazine (Phz), 4,4'-bipyridyl (Bpy), pyrimidine (Pym), 2-aminopyrimidine (PymNH(2)), 2,4-diaminopyrimidine (Pym(NH(2))(2)), 2,4,6-triaminopyrimidine (Pym(NH(2))(3)), quinazoline (Qnz), pyridazine (Pdz), and phthalazine (Ptz) were studied. Open reflux reactions produced complexes (CuCN)(2)(L) for L = Qox, Phz, Bpy, PymNH(2), Pym(NH(2))(2), Qnz, and Pdz and (CuCN)(3)(L) complexes for L = Pyz, PyzNH(2), Qox, Bpy, Pym(NH(2))(3), and Pdz. Also produced were (CuCN)(3)(Pyz)(2), (CuCN)(PyzNH(2)), (CuCN)7(Pym)(2), (CuCN)(5)(Qnz)(2) and (CuCN)(5)(Ptz)(2). X-ray structures are presented for (CuCN)(2)(Pdz), (CuCN)(2)(PymNH(2)), and (CuCN)(7)(Pym)(2). Hydrothermal reactions yielded additional X-ray structures of (CuCN)(2)(PyzNH(2)), (CuCN)(3)(Pym(NH(2))(2)), (CuCN)(4)(Qnz), a second (CuCN)(2)(Pdz) phase, (CuCN)(5)(Pdz)2, (CuCN)(2)(Ptz), and (CuCN)(7)(Ptz)2. Structural trends, including cuprophilic interactions and cyano-bridged Cu(2)(CN)(2) dimer formation, are discussed. Particularly short Cu...Cu interactions are noted for the novel 4- and 5-coordinate Cu(2)(CN)(2) dimers. Thermal analyses show that most of the complexes decompose with loss of L around 160-180 degrees C. Luminescence behavior is relatively weak in the products.

Vibrational–Structural Combined Study into Luminescent Mixed Copper(I)/Copper(II) Cyanide Coordination Polymers

“…CuCN itself is characterized by an emission band at λ = 392 nm in the solid state. [32,34] This luminescence results from electronic excitation between π character orbitals, in particular from the dCu/πCN highest occupied molecular orbital (HOMO) to the pCu/π*CN lowest unoccupied molecular orbital (LUMO). [31] After the coordination of ligands with N or S atoms as the binding site, the luminescence moves towards the visible region, as the presence of two different transitions leads to two possible emissive paths: metal to CN ligand and metal to S/Nligand; the CC transitions can be discounted if the Cu···Cu distance is longer than 2.8 Å.…”

Solvent-Free Synthesis of Luminescent Copper(I) Coordination Polymers with Thiourea Derivatives

“…8 CuCN itself is characterized by a weak luminescence. 9 However, its photoluminescence emission interestingly shifts from the near UV (392 nm) into the visible region upon the coordination of nucleophiles, while the intensity increases by several orders of magnitude. In some cases, small differences in the ligands, such as the presence of methyl or ethyl groups like in piperazine, methylpiperazine, and ethylpiperazine, can result in remarkable differences in the emission color of the obtained coordination polymers, providing several luminescence tuning possibilities.…”

3D-Interpenetrating Frameworks of 3∞[Cu2(CN)4(Me3Pb)2(bpy)] Containing the Rhombic [Cu2(µ3-CN)2] Motifs

“…The [Cu 2 (l 3 -CN) 2 ] motifs seem to display the essential role as the main building block in the structure of 1. It is worth mentioned that the number of the SCP containing the rhombic [Cu 2 (l 3 -CN) 2 ] motifs is now growing up [7,9,[18][19][20][21][22][23][24][25][26] presenting a rich collection of structural data on cyanide groups point towards the copper ions producing l 3 -CN units. The previously described 3D-framework of the coordination polymer [Cu 2 (CN) 2 (pip)] (pip = piprazine) even seems to involve l 4 -CN units, i.e.…”

“…The presence of the [Cu 2 (l 3 -CN) 2 ] fragments having two bifurcated cyanide groups leads to bridge the corrugated chains via the bpy ligand developing 3D-network structure. The presence of the rhombic [Cu 2 (l 3 -CN) 2 ] fragment acquires the formation of bent CN groups, Cu2-C4-N12 = 160.20 (3) [18,19,[21][22][23][24][25][26], present in the rhombic motifs. However, the Cu2 ii -C4 ii distance is shorter exhibiting bond length equals to 1.950 Å .…”