Hirshfeld Surface Analysis for Investigation of Intermolecular Interaction of Molecular Crystals

Hirshfeld surface analysis has been widely used in recent years as a means to quantify and visualize various types of intermolecular interactions in molecular crystals. This review article introduces intermolecular interactions discussed with Hirshfeld surface analysis and 2D fingerprint plots. In addition, using CIF files obtained from our previous results, Hirshfeld surface analysis was newly performed, and the resulting 3DHirshfeld surfaces, 2D print plots, molecular structural features, and crystal structure relationships were described. Classification of their intermolecular interactions, statistical discussion focused on crystalline water and perspective on ligand-protein docking are also mentioned.

A New Dinuclear Zinc Polymer Based on 3-Methoxy-2-hydroxybenzaldehyde:Synthesis,Structure,Spectral Characterization and Hirshfeld Surface Analysis

A highly efficient fluorescence material dinuclear zinc polymer [Zn2（mhbd）2（dca）2]n （1, Hmhbd is 3-methoxy-2-hydroxybenzaldehyde, dca is N（CN）2？） has been synthesized under room temperature and structurally characterized by elemental analysis, IR, and single-crystal X-ray diffraction. The structure belongs to the triclinic system, space group P with a = 8.475（1）, b = 9.595（1）, c = 15.001（1） A, α = 86.84（1）, β = 81.10（1）, γ = 68.78（1）°, Mr = 565.15, V = 1123.5（1） ？3, Dc = 1.671 g？cm–3, F（000） = 568, μ = 2.185 mm–1, R = 0.0451, and wR = 0.1297. 1 is a dinuclear zinc complex which further constructs a 1D chain through double μ1,5-dca bridge. Luminescent property and Hirshfeld surface analysis of 1 have been studied. The result indicates that the fluorescence intensity of complex 1 is forty-one times the fluorescence intensity of Hmhbd ligand.

A Novel Dinuclear Copper(Ⅱ)Complex:Synthesis,Crystal Structure,Properties and Hirshfeld Surface Analysis

A novel copper complex [Cu2（L）（DMF）2]（1, H4L =（1 Z,N？Z）-3,5-dibromo-N？-（（3,5-dibromo-2-hydroxyphenyl）（hydroxy）methylene）-2-hydroxybenzohydrazonic acid which was synthesized by in-situ oxidation reaction derived from H2hdb（H2hdb = 6,6′-（（1 E,1？E）-hydrazine-1,2-diylidenebis（methanylylidene）） bis（2,4-dibromophenol）） has been synthesized and characterized by IR, elemental analysis（CHN）, TG and single-crystal X-ray diffraction. The single crystal belongs to monoclinic system, space group P21/c with a = 13.538（1）, b = 3.912（1）, c = 23.778（1）A°, β = 105.232（5）o, Mr = 857.08, V = 1214.9（1） A°^3, Z = 2, Dc = 2.343 g/cm^3, F（000） = 824, μ = 8.375 mm^–1, R = 0.0566, and w R = 0.1610. Compound 1 displays weak anti-ferromagnetic interactions through a η^1：η^1：η^1：η^1：η^1：η^1：μ2-L^4- bridging mode. Hirshfeld surface analysis revealed that complex 1 was supported mainly by Br···H and H···H intermolecular interactions.

One Novel 2D Co(Ⅱ) Polymer with 1,2,3-Triazole Derivative: Crystal Structure, Fluorescence and Hirshfeld Surface Analysis

One new polymer [Co（L）（H2O）2]n（1） was synthesized by 4-（ethoxycarbonyl）-5-methyl-1H-1,2,3-triazole-1-carboxylic acid（Emtc） under the in situ solvent thermal reaction（H2L = 1-（carboxymethyl）-5-methyl-1H-1,2,3-triazole-4-carboxylic acid）. The title complex performs a wave-like 2D framework and the ligand H2L demonstrates the coordination mode as μ4-η-2：η-1η-1：η-1. The crystal structure has been established by single-crystal X-ray diffraction, and characterized by FT-IR. Fluorescent property was investigated in this work. Hirshfeld surface analysis has also been carried out on 1, and obvious main intermolecular interactions are observed.

Analysis of Intra-and Intermolecular Hydrogen Bonds and Quantum Chemical Calculations on 1-(3-Fluorobenzoyl)-3-(4-trifluoromethylphenyl)thiourea

1-（3-Fluorobenzoyl）-3-（4-trifluoromethylphenyl）thiourea, C15H10F4N2OS, has been synthesized firstly and determined by single-crystal X-ray diffraction analysis. The title compound crystallizes in monoclinic system, space group C2/c with a = 31.87（3）, b = 7.705（9）, c = 12.591（14） A°, b = 106.06（2）°, V = 2971（6） A°^3, Z = 8, Dc=1.530 g·cm^-1, F（000） = 1392, m = 0.266 mm^–1, S = 1.06, the final R = 0.070 and w R（I 〉 2s（I）） = 0.249. The crystal structure revealed that the carbonyl thiourea unit in the determined compound was mostly planar due in part to the formation of intramolecular N–H···O=C and C–H···S=C hydrogen bonds that form two S（6） rings. The intermolecular contacts of the crystal structure have been preformed based on the Hirshfeld surface and their associated 2D fingerprint plots. In the packing diagram of the synthesized compound, the C=S group formed two types of intermolecular hydrogen bonds by the H–N（C=O） group and the H–C of the phenyl ring, respectively, and they formed R2^2（8） and R2^2（14） ring motifs, respectively. The crystal packing form was also stabilized by the intermolecular hydrogen bonds C–H···O（1–x, y, 0.5–z） with the R2^2（10） ring motifs. In addition, supramolecular layers sustained by π-π stacking interactions（between the C（2）～C（7） rings with the C（10）～C（15） rings） are formed in the crystal structure of the title compound. The electronic and reactivity were assessed by the natural bond orbital（NBO） analysis in this study.

Crystal and Molecular Structure Analysis in Knoevenagel Condensation Product of Substituted Napthofuran-2-Carbaldehydes

In the current study, two novel Knoevenagel condensation products of substituted napthofuran-2-carbaldehydes were designed, synthesized and characterized. In order to study the intermolecular interactions of title compounds, single crystals were grown by slow evaporation solution growth technique at room temperature and crystal structure has been determined by single crystal X-ray diffraction technique. Both the molecules crystallize in the monoclinic centrosymmetric space group P21/c with one molecule in the asymmetric unit. In compound [4] the molecules are connected via bifurcated C-H···O=C and C-H···N=C H-bonds and van der Waals interactions forming a layered structure, whereas in compound [5a] the molecular conformation is stabilized via intramolecular C-H···O H-bond and molecule interacts with other molecule generated via 21-screw via bifurcated C-H···O=C along with C-H···N=C H-bonds, which are interacting with nitro- of other molecule generated via same symmetry operation, forming bifurcated C-H···O-N H-bonds, which helps in formation of molecular sheet-like structure.Further, in order to understand the various types and nature of intermolecular interactions in the supramolecular structure Hirshfeld surface analysis and fingerprint plot analysis was carried out.

A New Non-centrosymmetric Microporous Fluorinated Iron Phosphate： Structural Elucidation, Spectroscopic Study and Hirshfeld Surface Analysis

The crystal structure of a new non-centrosymmetric microporous fluorinated iron phosphate, （H30）2[Fe4（H2O）2F4（PO4）2（HPO4）2]（H2O）, was determined by single crystal X-ray diffraction analysis and the result reveals that it belongs to the orthorhombic system with four molecules in the unit cell（space group P212121）. Thus, the complex was characterized by powder X-ray diffraction, spectroscopic techniques（Fourier transform infrared and Fourier transform Raman） and 19F MAS NMR. The elemental analysis of the sample was also carried out. The chiral inorganic sheets, which stacked along [100] showed the presence of FeF2O4 as well as FeF2O3H2O octahedra, PO4 besides HPO4 tetrahedra, hydronium ions（H3O＋） and isolated water molecules. Hirshfeld surface analysis, especially dnom surface and fingerprint plots, were used for decoding the intermolecular interactions in the crystal network and the contribution of component units for the construction of the 3D architecture. From the Hirshfeld surfaces and 2D fingerprint analysis, it was found that the subtle interactions, such as H...H associating the third intense interaction of all intercontacts, provide extra stabilization in addition to the presence of the strong hydrogen bonds mentioned above.

Crystal structures and phase transitions in two new hybrid crystals: (Me_(3)NCH_(2)CH_(2)X)_(4)[Ni(NCS)_6](X=Cl and Br)

Understanding phase transitions in multi-component crystals is of importance for regulating specified functional materials.Herein,we present two new organic-inorganic hybrid crystals,(Me_(3)NCH_(2)CH_(2)X)_(4)[Ni(NCS)_6](X=Cl and Br),revealing distinct phase transitions.Specifically,the Clsubstituted cations weakly interact with discrete inorganic part hence reveal step-wise dynamic changes upon heating,which result in multi-step solid-solid phase transitions (P1-P2_1/n-A2/a-Cmce) including a ferroelastic one with a spontaneous strain of 0.0475.Whereas the Br-substituted cations with larger steric effect prevent the solid-solid phase transition but give a solid-liquid phase transition at above 419 K.The present instances well demonstrate the complicity for multi-component crystals arising from the delicate balance established by abundant weak intermolecular interactions,and inspire the design of novel phase-transition materials by judiciously assembling multi-component crystals.