The preparation, X-ray crystal structure, Fourier Transform infrared (FTIR) spectroscopy, and elemental analysis of the four compounds based on hexamethylenetetramine, and N, N, N, N-tetramethylethylenediamine are reported. XRD and FTIR analysis indicated that the compound 1 is a cocrystal, while 2-4 are organic salts. The compound 1 crystallizes in the triclinic, space group P-1, with a = 7.9280(6) Å, b = 11.1452(9) Å, c = 18.2226(16) Å, α = 80.9580(10)°, β = 86.285(2)°, γ = 70.1740(10)°,V = 1495.8(2) Å3, Z = 2. The compound 2 crystallizes in the monoclinic, space group P2(1)/c, with a = 11.4207(9) Å, b = 10.1095(6) Å, c = 14.9048(12) Å, α = 90°, β = 96.2950(10)°, γ = 90°, V = 1710.5(2) Å3, Z = 4. The compound 3 crystallizes in the Triclinic, space group P-1, with a = 7.6542(6) Å, b = 12.2296(11) Å, c = 13.9565(12) Å, α = 67.6900(10)°, β = 85.571(2)°, γ = 71.8270(10)°, V = 1147.09(17) Å3, Z = 2. The compound 4 crystallizes in the monoclinic, space group P2(1)/c, with a = 6.9377(5) Å, b = 12.0824(9) Å, c = 12.1639(11) Å, α = 90°, β = 94.6840(10)°, γ = 90°, V = 1016.22(14) Å3, Z = 2. In this work, the hexamethylenetetramine at 1–2 formed two, three and four classical hydrogen bonds, respectively. Each NH+ at the diprotonated N, N, N, N-tetramethylethylenediamine generated one or two hydrogen bonds. In addition to the classical hydrogen bonds, the auxiliary expanding interactions as CH–O, CH2–O, CH3–O, CH2···Cπ, CH2-π and CH3-π also play important roles in the structure extension. In conclusion, we have shown that 3D structures can be constructed by the collective non-covalent interactions.
Graphical Abstract
In the four prepared supramolecular assemblies there are plenty of weak nonbonding interactions such as directional hydrogen bonds of O–H···N, N–H···O, O–H···O, N–H···S, intra- and interchain CH–O, CH2···O, CH3–O, CH2···Cπ, CH2-π and CH3-π interactions. Due to these collective weak interactions, all the compounds displayed the 3D framework structures.