Long bipyridyl-type linking ligands containing an intervening cyclohexyl fragment and their cadmium coordination polymers: and (Ln=(n-py)–CHN–C6H10–NCH–(n-py); n=4,3,2)

Crystal structure of hemikis(cyclohexane-1,4-diammonium) (pyridine-2-carboxylate), [C6H16N2]0.5[C6H4NO2]

[C6H16N2]0.5[C6H4NO2], triclinic, P1̄ (no. 2), a = 6.7956(2) Å, b = 7.2840(3) Å, c = 10.2615(4) Å, α = 70.483(3)°, β = 80.902(3)°, γ = 66.404(3)°, V = 438.55(3) Å3, Z = 2, R gt(F) = 0.0359, wR ref(F 2) = 0.0988, T = 100(2) K.

Crystal structure and DFT study of (E)-4-[({4-[(pyri-din-2-yl-methyl-idene)amino]-phen-yl}amino)-meth-yl]phenol

In the title Schiff base compound, C19H17N3O, the configuration about the C=N bond is E. The mol-ecule is non-planar, with the phenolic and pyridine rings being inclined to the central benzene ring by 56.59 (4) and 15.13 (14)°, respectively. In the crystal, mol-ecules are linked by pairs of O-H⋯N hydrogen bonds, forming inversion dimers. The dimers are connected to neighbouring dimers by N-H⋯O hydrogen bonds and C-H⋯π inter-actions, forming layers parallel to the bc plane. The layers are linked by offset π-π inter-actions [inter-centroid distance = 3.779 (2) Å], forming a three-dimensional supra-molecular structure. Quantum chemical calculations of the mol-ecule are in good agreement with the solid-state structure.

Crystal structure of N,N'-bis-(pyridin-3-ylmeth-yl)cyclo-hexane-1,4-di-ammonium dichloride

The title salt, C18H26N42+·2Cl-, was obtained by the protonation of N,N-bis-(pyridin-4-ylmeth-yl)cyclo-hexane-1,4-di-amine with hydro-chloric acid in ethanol. The asymmetric unit consists of one half of an N,N-bis-(pyridin-3-ylmeth-yl)cyclo-hexane-1,4-di-ammonium dication, with a crystallographic inversion centre located at the centre of the cyclo-hexyl ring, and a chloride anion. The central cyclo-hexyl ring in the dication adopts a chair conformation. The two trans-(4-pyridine)-CH2-NH2- moieties at the 1- and 4-positions of the central cyclo-hexyl ring occupy equatorial sites. The terminal pyridine ring is tilted by 53.72 (6)° with respect to the mean plane of the central cyclo-hexyl ring (r.m.s. deviation = 0.2413 Å). In the crystal, N+-H⋯Cl- hydrogen bonds between the dications and the chloride anions, and π-π stacking inter-actions between the pyridine rings of the dications afford a two-dimensional sheet extending parallel to the ab plane. These sheets are further connected through weak C-H⋯Cl- hydrogen bonds, resulting in the formation of a three-dimensional supra-molecular network.

Crystal structure of N,N'-bis-(pyridin-4-ylmeth-yl)cyclo-hexane-1,4-di-ammonium dichloride dihydrate

Treatment of N,N-bis-(pyridin-4-ylmeth-yl)cyclo-hexane-1,4-di-amine with hydro-chloric acid in ethanol led to the formation of the title salt, C18H26N42+·2Cl-·2H2O, which lies about a crystallographic inversion center at the center of the cyclo-hexyl ring. The asymmetric unit therefore comprises one half of the N,N-bis-(pyridin-4-ylmeth-yl)cyclo-hexane-1,4-di-ammonium dication, a chloride anion, and a solvent water mol-ecule. In the dication, the two trans-(4-pyridine)-CH2-NH2- moieties occupy equatorial sites at the 1- and 4-positions of the central cyclo-hexyl ring, which is in a chair conformation. The terminal pyridine ring is tilted by 27.98 (5)° with respect to the mean plane of the central cyclo-hexyl moiety (r.m.s. deviation = 0.2379 Å). In the crystal, dications, anions, and solvent water mol-ecules are connected via N/C/O-H⋯Cl and N-H⋯O hydrogen bonds together with C-H⋯π inter-actions, forming a three-dimensional network.

4-({[(E)-Pyridin-3-yl-methyl-idene]amino}-meth-yl)cyclo-hexa-necarb-oxy-lic acid

The title compound, C₁₄H₁₈N₂O₂, contains two geometrically different mol­ecules in the asymmetric unit: the basal plane of the cyclo­hexane chair and the N-[pyridin-3-yl­methyl­idene]methanamine moiety are oriented at dihedral angles of 71.77 (7)° and 83.42 (8)°. In the crystal, the mol­ecules are linked by O—H⋯N hydrogen bonds, generating C(13) head-to-tail chains extending along the base vector [103]. R₂²(26) ring motifs are formed due to the C—H⋯·O inter­actions that link neighbouring chains. There also exist π–π inter­actions [centroid–centroid separation = 3.6925 (12) Å] between the symmetry-related pyridine rings of one of the independent mol­ecules.