Comparitive study on structural, magnetic and spectroscopic properties of four new copper(II) coordination polymers with 4′-substituted terpyridine ligands

Abstract

International audienceThe synthesis and characterization of four copper(II) complexes with different terpyridyl ligands have been carried out, their crystal and molecular structures determined and their magnetic and luminescent properties analyzed. The ligands used in the coordination reactions were 4′-(3-methyl-2-thienyl)-4,2′:6′,4''-terpyridine (4-stpy), -4′-(4-quinolinyl)-4,2′:6′,4''-terpyridine (4-qtpy), 4′-(4-quinolinyl)-3,2′:6′,3''-terpyridine (3-qtpy, unreported so far) and 4′-(4-cyanophenyl)-4,2′:6′,4''-terpyridine (4-cntpy); the reaction of these ligands with Cu(II)-hexafluoroacetylacetone (Cu(hfacac)2) gives rise to coordination polymers Cu(4-stpy)(hfacac)2 (I), Cu(4-qtpy)(hfacac)2 (II), Cu(3-qtpy)(hfacac)2 (III) and Cu(4-cntpy)(hfacac)2 (IV). The different location of the nitrogen atom of the outer ring is responsible for the different coordination modes. The emission spectra of dichloromethane solutions are consistent with dissociation of the complexes; the emission maxima simulate those of the free ligands. The emission of I, III and IV in the solid state is essentially quenched upon complexation with Cu(II), whereas for compound II an emission at 420 nm is observed. The interaction between copper centers has been related with the coplanarity of terpyridine rings. Complexes I–III exhibit a paramagnetic behavior, while compound IV, with the smallest torsion angle between pyridine moieties, shows an antiferromagnetic behavior described by a dimeric model, with J=−4.38 cm−1, g =2.06 and ρ=0.07

Isomeric 4,2′:6′,4″- and 3,2′:6′,3″-Terpyridines with Isomeric 4′-Trifluoromethylphenyl Substituents: Effects on the Assembly of Coordination Polymers with [Cu(hfacac)2] (Hhfacac = Hexafluoropentane-2,4-dione)

“…It is tempting to suggest that this is due to the steric hindrance of the {Cu(hfacac) 2 } domains. We note that there are also no π-stacking interactions between 4,2 :6 ,4"-tpy domains in the 1D-polymers [Cu(hfacac) 2 (L 2 )] n •CHCl 3 and [Cu(hfacac) 2 (L 4 )] n (see Scheme 2 for L 2 and L 4 ) [36], although Moreno and coworkers did observe π-stacking of 4,2 :6 ,4"-tpy units in the molecular complex [Cu 3 (ttfacac) 6 (L 1 ) 2 ] (L 1 , see Scheme 2) [37]. Another similarity between [Cu 2 (hfacac) 4 (1) Having investigated the effects of moving the substitution position of the CF3 group while retaining a 4,2′:6′,4″-tpy metal-binding unit on going from 1 to 2, we turned our attention to ligands 3 and 4 with 3,2′:6′,3″-tpy domains.…”

“…and [Cu(hfacac) 2 (L 4 )] n (L 1 -L 4 are defined in Scheme 2) [36]. All four compounds are 1D-coordination polymers with 4,2 :6 ,4"-or 3,2 :6 ,3"-tpy domains linking octahedral Cu(II) centers.…”

“…We note that there are also no π-stacking interactions between 4,2′:6′,4″-tpy domains in the 1D-polymers [Cu(hfacac)2(L2)]n . CHCl3 and [Cu(hfacac)2(L4)]n (see Scheme 2 for L2 and L4)[36], although Moreno and coworkers did observe π-stacking of 4,2′:6′,4″-tpy units in the molecular complex [Cu3(ttfacac)6(L1)2] (L1, see Scheme 2)[37]. Another similarity between [Cu2(hfacac)4(1)2]n .…”

Influence of structural changes on photophysical properties of terpyridine derivates: Experimental studies and theoretical calculations

“…have been prepared as previously reported. 15,24 Microanalyses were recorded on a Thermo-FINNIGAN Flash EA 1112 CHNS/O analyzer at the Microanalytical Service of the CRMPO at the University of Rennes 1, France. NMR spectroscopy: 1 H and 13 C NMR spectra in CDCl 3 solution were recorded on a Bruker-400 NMR spectrometer (chemical shifts referenced to residual solvent peaks, δTMS= 0).…”

Multitopic 3,2′:6′,3′′-terpyridine ligands as 4-connecting nodes in two-dimensional 4,4-networks

“…Although many examples of 1D-, 2D- and 3D-assemblies have been prepared from ligands containing one or more 4,2′:6′,4′′-tpy units, the coordination behaviour of 3,2′:6′,3′′-tpy ligands remains less exploited. 1,5–25 We have reported three copper( ii ) 1D-coordination polymers [Cu 2 (hfacac) 4 (L1) 2 ] n · n (1,2-Cl 2 C 6 H 4 ) (Hhfacac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione), [Cu 2 (hfacac) 4 (L1) 2 ] n · n C 6 H 5 Cl, and [Cu(hfacac) 2 (L2)] n · n C 6 H 5 Cl, containing ditopic 3,2′:6′,3′′-tpy ligands with coordinatively innocent 4′-substituents. In [Cu 2 (hfacac) 4 (L1) 2 ] n · n (1,2-Cl 2 C 6 H 4 ) and [Cu 2 (hfacac) 4 (L2) 2 ] n · n C 6 H 5 Cl the 3,2′:6′,3′′-tpy domains exhibit conformation C , while with [Cu(hfacac) 2 (L2)] n · n C 6 H 5 Cl conformation B is adopted (Scheme 1).…”