Two novel symmetric fluorene-based ligands, namely, 2,7-bis(1H-imidazol-1-yl)-9,9-dimethyl-9H-fluorene [L1 or (I), C21H18N4] and 2,7-bis(1H-imidazol-1-yl)-9,9-dipropyl-9H-fluorene (L2), have been used to construct the coordination polymerscatena-poly[[dichloridodicopper(I)(Cu—Cu)]-μ-2,7-bis(1H-imidazol-1-yl)-9,9-dimethyl-9H-fluorene], [Cu2Cl2(C21H18N4)]n, (II), andcatena-poly[[tetra-μ2-chlorido-tetracopper(I)]-bis[μ-2,7-bis(1H-imidazol-1-yl)-9,9-dipropyl-9H-fluorene]], [Cu4Cl4(C25H26N4)2]n, (III). There are three types of C—H...N hydrogen bonds in (I), resulting a two-dimensional network in theabplane, including a chiral helical chain along thebaxis. Compounds (II) and (III) are related one-dimensional polymers. In both, CuIatoms connect the symmetric ligands (L1 orL2) into a one-dimensional chain. In (II), the {[CuICl2]−} unit, acting as a co-anion, adheres to the one-dimensional chain through a weak Cu...Cu interaction. However, in (III), the {[CuI2Cl4]2−} unit links two different chains into a one-dimensional rope-ladder-type chain. In addition, there are C—H...Cl hydrogen bonds and π–π interactions in the extended structures of (II) and (III), the difference is that the chains in (II) are linked into a two-dimensional network while the chains in (III) are stacked into a three-dimensional framework.
Construcción y caracterización de un cristal artificial elástico
