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 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.

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.

Crystal Structure, Hirshfeld Surface Analysis and Quantum Mechanical Study of a Cocrystal Based on 1,3-Di（4-pyridyl）propane and 3-（（4~′-Carboxybenzyl）oxy） Benzoic Acid

A cocrystal based on 1,3-di（4-pyridyl）propane and 3-（（4′-carboxybenzyl）oxy）benzoic acid,C13H14N2·C15H12O5,has been synthesized and characterized by single-crystal X-ray diffraction.The compound crystallizes in monoclinic,space group P21 /c with a = 11.639（4）,b = 9.808（3）,c = 20.854（6）,β = 91.242（7）°,V = 2380.0（13）3,C28H26N2O5,Mr = 470.51,Dc = 1.313 g/cm3,μ（MoKα） = 0.091 mm-1,F（000） = 992,Z = 4,the final R = 0.0677 and wR = 0.1477 for 4175 observed reflections（I 2σ（I））.Intermolecular N H···O hydrogen bonds link two kinds of components into a one-dimensional chain in [10-1] direction and adjacent chains are further arranged into a two-dimensional network by π···π and C H···π interactions.Investigation of intermolecular interactions and crystal packing via Hirshfeld surface analysis reveals that the close contacts are mainly focused on weak interactions.The theoretical investigations with HF/6-31G（d） method were performed,and its stability,frontier molecular orbital composition and Mulliken charge distribution were also discussed.

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.

One Novel Mn(Ⅱ)Complex with 1-Substituted-1H-1,2,3-triazole-4-carboxylic Acid:Crystal Structure,Fluorescence and Hirshfeld Surface Analysis

The crystal structure of one novel Mn（II） complex, [Mn（pmta）_3]_2[Mn（H_2O）_6]·4H_2O（1）, is reported（Hpmta = 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid）. In the title compound, the asymmetric unit consists of a [Mn（pmta_）3]ˉ anion, half [Mn（H_2O）_6]^（2＋） counter cation and two lattice H_2O molecules, and the intra- and intermolecular hydrogen bonds connect the complex into a supramolecular structure. The liquid-state fluorescence spectra of complex 1 have been determined. Hirshfeld surface analysis was also studied. The main intermolecular interactions in the complex are O···H and H···H contacts.

Novel Perchlorate and Sulphate Salts of 2-Aminonicotinic Acid:Synthesis,Characterization,Thermal Studies and Hirshfeld Surface Analysis

Since 2-aminonicotinic acid is a zwitterionic molecule,the salt or co-crystal strategy was used for the precipitation under identical conditions and obtained two novel salts： salt 1 with 2：1：2 stoichiometry of 2-aminonicotinic acid：perchloric acid：H2O and salt 2 with 2：1：3 stoichiometry of 2-aminonicotinic acid：sulfuric acid：H2O. Their crystal structures were characterized by single-crystal X-ray diffraction,differential scanning calorimetry（DSC） and thermogravimetric analyses（TGA）. The structure determination shows that two salts are both primarily stabilized by the strong N–H…O hydrogen bonding interaction between 2-aminonicotinic acid and its corresponding acids. Constituents of the salt-crystalline phase were also investigated in terms of Hirshfeld surfaces. In the crystal lattice,a three-dimensional hydrogen-bonded network is observed,including the formation of a two-dimensional molecular scaffolding motif. Hirshfeld surfaces and fingerprint plots of two salts show that the structures are stabilized by H…H,O–H…O and C–O…π intermolecular interactions.

白桦脂酸-乙醇(1:1)的晶体结构及Hirshfeld Surface分析

白桦脂酸是一种具有多种药理活性的五环三萜类天然产物,已报道的其单晶体均为白桦脂酸-有机溶剂形式。本研究通过溶剂挥发法制备了白桦脂酸-乙醇(1:1)单晶体,通过X射线衍射法获得了其单晶数据,用Hirshfeld surface分析法对晶体中分子间作用力进行了分析。晶体结构分析结果为揭示其理化性质与成因等提供了基础科学数据,为该晶型的定性、定量分析及制备工艺研究提了标准依据,为白桦脂酸多晶型的筛选及共晶的设计提供了数据参考。

Physicochemical characterization, the Hirshfeld surface, and biological evaluation of two meloxicam compounding pharmacy samples

Meloxicam(MLX) is an anti-inflammatory drug susceptible to variations and crystalline transitions. In compounding pharmacies, the complete crystallographic evaluation of the raw material is not a routine procedure. We performed a complete crystallographic characterization of aleatory raw MLX samples from compounding pharmacies. X-ray diffraction indicated the presence of two crystalline forms in one sample. DSC experiments suggested that crystallization, or a crystal transition, occurred differently between samples. The FTIR and ~1H NMR spectra showed characteristic assignments.^(13)C solid-state NMR spectroscopy indicated the presence of more than one phase in a sample from pharmacy B. The Hirshfeld surface analysis, with electrostatic potential projection, allowed complete assignment of the UV spectra in ethanol solution. The polymorph I of meloxicam was more active than polymorph III in an experimental model of acute inflammation in mice. Our results highlighted the need for complete crystallographic characterization and the separation of freely used raw materials in compounding pharmacies,as a routine procedure, to ensure the desired dose/effect.

Structural Investigation,Quantum Mechanical Study and Hirshfeld Surface Analysis of One Novel Adduct Based on Aminopyridinium and Biphenyl-2,4′-dicarboxylate

One novel adduct based on aminopyridinium and biphenyl-2,4′-dicarboxylate, C5H7N2＋·C14H9O4-, has been synthesized and characterized by X-ray structural study. The compound crystallizes in trigonal, space group P32 with a = 9.2886（16）, b = 9.2886（16）, c = 16.746（6） , γ = 120°, V = 1251.2（5） 3, C19H16N2O4, Mr = 336.34, Dc = 1.339 g/cm3, μ（MoKα） = 0.095 mm-1, F（000） = 528, Z = 3, the final R = 0.0438 and wR = 0.1119 for 3097 observed reflections （Ⅰ 〉 2σ（Ⅰ））. Its electronic structure was calculated at the RHF/6-31G（d） level and a detailed analysis of intermolecular interactions was used by Hirshfeld surface and fingerprint plot. Intermolecular N-H…O hydrogen bonds link two components generating R22（8） rings which are linked into three one-dimensional chains in the [100], [010] and [110] directions, and these chains are finally arranged into a three-dimensional framework by hydrogen bonds. Investigation of intermolecular interactions via Hirshfeld surface analysis reveals that the close contacts are mainly associated with the classical hydrogen bonding interactions. The HOMO-LUMO energy gap of the compound indicates a higher kinetic stability.

Crystal Packing Studies, Thermal Properties and Hirshfeld Surface Analysis in the Zn(II) Complex of 3-Aminopyridine with Thiocyanate as Co-Ligand

Reaction of zinc acetate, potassium thiocyanate and the ligand 3-ampy gave the discrete tetrahedral complex [Zn(NCS)2(3-ampy)2] in which 3-ampy chelates in a monodentate fashion through its pyridine-N atom. It was characterized by single crystal X-ray diffraction, infrared, and elemental analysis. Density Functional Theory calculations were performed in order to gain insights into the role of weak molecular interactions in the complex that influence the self-assembly process and crystal packing. X---H (X = H, C, N and S) inter-actions. S-H interactions (30.2%) were found to be the main interactions that hold the molecules in the crystal structure. Furthermore, the thermolysis of the complex was studied in order to evaluate whether it was suitable as a precursor for zinc sulphide.

Crystal Structures,Luminescent Properties and Hirshfeld Surface Analyses of Zn(Ⅱ)and Cd(Ⅱ)Compounds Based on 1-(2-Carboxyl-phenyl)-3-(pyridin-2-yl)pyrazole

Two compounds,[Zn2（Hcppp）2（cppp）2（H2O）2]·2 NO3·6 H2O（1） and [Cd（Hcppp）2Cl2]· 3H2O（2）（Hcppp = 1-（2-carboxyl-phenyl）-3-（pyridin-2-yl）pyrazole）,are synthesized and characterized by IR,TGA and X-ray single-crystal/powder diffraction.Compound 1 crystallizes in monoclinic system,space group P21/c with a = 9.894（2）,b = 15.856（3）,c = 20.430（4） A,β = 101.70（3）°,V = 3138.5（11） A3,Z = 2,Mr = 1457.94,Dc = 1.543 g/cm^3,F（000） = 1504,R = 0.0278 and wR = 0.0749 for 6157 observed reflections（I 〉 2σ（I））.Compound 2 crystallizes in triclinic system,space group P1 with a = 9.1424（4）,b = 11.6427（5）,c = 16.1345（7） A,α = 102.6430（10）°,β = 95.4530（10）°,γ = 104.0060（10）°,V = 1605.94（12） A3,Z = 2,Mr = 767.88,Dc = 1.588 g/cm^3,F（000） = 776,R = 0.0307 and wR = 0.0764 for 6275 observed reflections（I 〉 2σ（I））.Compound 1 exhibits a binuclear structure while compound 2 shows a mononuclear structure.In compound 1,two cppp-ligands display the μ2-kN,N′：k O and two Hcppp ligands show the μ1-kN,N′ coordination modes.However,two Hcppp ligands connect one Cd（Ⅱ） cation and exhibit the μ1-kN,N′ binding mode in compound 2.The compounds are both studied using Hirshfeld surface analyses and 2D fingerprint plots.The luminescent properties are also discussed.

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.

双吡唑甲烷配合物的合成、晶体结构及性质

采用溶液法成功地合成两种新的双吡唑甲烷配合物[Ag_(2)(bpm)_(2)](NO_(3))_(2)(1)和[Pd(bpm)2]Cl·H_(2)O(2),(bpm:bis(pyrazol)methane),通过红外光谱、元素分析和X-射线单晶衍射等手段确定双吡唑甲烷配合物的晶体结构。X-射线单晶衍射研究表明,配合物1是[Ag_(2)]二聚体,通过氢键作用组装成一维链状结构;配合物2是Pd(II)单核结构,通过氢键形成三维超分子结构。对目标配合物的室温荧光光谱以及Hirshfeld surface表面作用力,研究结果表明,与自由配体bpm相比,配合物的荧光轻微蓝移;配合物1和2的主要相互作用分别是O…H/H…O和H…H接触。

Effect of Changing Anion on the Crystalline Structure, Crystal Structure, Hirschfield Surface, IR and NMR Spectroscopy of Organic Salts and Hybrid Compounds: C6H4(NH3)2Cl2 (I), β-[C6H10N2]2ZnCl4 (II), Respectively

Two organic-inorganic hybrid materials, C6H4(NH3)2∙Cl2 (I) and β-[C6H10N2]2ZnCl4 (II), have been synthesized by hydrothermal method. These two materials are one of the hybrid materials have emerged as one of the most brilliant components classes. These extraordinary compounds synergistically combine the desired physical properties of both organic and inorganic components into a single compound offering the possibility to achieve great improvement over time in terms of science across various sectors. Their structures were determined by XRD pattern investigations and single crystal X-ray diffraction. These two compounds are crystallized in the monoclinic system;C2/c space group. In the both structures, the anionic-cationic entities are interconnected by hydrogen bonding contacts and p-p Interaction forming three-dimensional networks. Intermolecular interactions were investigated by Hirshfeld surfaces and the contacts of the four different chloride atoms in (II) were compared. The vibrational absorption bands were identified by infrared spectroscopy. These compounds were also investigated by solid state13C NMR spectroscopy.

Syntheses,Crystal Structures and Theoretical Studies of Three Novel Salts of Vortioxetine and the Investigation of Their Solubility

Three new vortioxexine （VOT） salts with salicylic acid （SA）, 5-fluorouracil （FU） and （p-nitrophenyl）-acetic acid （PA） have been synthesized and characterized in detail. In VOT-SA（1：1）, the protonated VOT and deprotonated salicylic anion form a tetrameric unit with the R4 4（12） synthon via N（1）–H（1）…O（1）^a （a： x–1, y, z） and N（1）–H（2）…O（2）^b （b： –x, –y, –z＋1） hydrogen bonds. However, in VOT–FU（1：2）, the protonated VOT and deprotonated 5-fluorouracil anion feature an R4 4（16） ring motif via N（1）–H（1）…O（2）^c （c： –x＋1, –y＋1, –z＋1） and N（1）– H（2）…O（1）^d （d： x, y–1, z） hydrogen bonds. The neutral FU extends the R4 4（16） ring to form a two-dimensional structure through R2 2（8） N–H…O and N（6）–H（4）…N（4）……e （e： –x＋1, y–1/2, –z＋1/2） hydrogen bonds. In VOT-PA（1：1）, PA molecules are linked through N（1）–H（1）…O（1）f （f： –x＋1, y＋1/2, –z＋1） and N（1）–H（2）…O（2）, which forms a right-handed helical structure. Furthermore, components of the crystalline phase have also been investigated in terms of their corresponding Hirshfeld surface, and the salification improves the equilibrium solubilities and dissolution rates of VOT in three salts at 25 ℃ in water.

Crystal Structure and Theoretical Studies of Tetrahytrate(1-H-1,2,4-triazole-3,5-dicarboxylicacid)nickel

A new compound, [Ni（Hdctrz）（H2O）4]（1, H3dctrz = 1-H-1,2,4-triazole-3,5-dicarboxylic acid）, has been successfully synthesized via slow evaporation. The structure of 1 was characterized by FT-IR, elemental analysis and single-crystal X-ray diffraction. Compound 1 crystallizes in monoclinic, space group P21/c with a = 6.871（1）, b = 11.468（1）, c = 12.178（1） A, b = 101.291（1）o, V = 941.01（16） A3, Z = 4, C4H9N3O8Ni, Mr = 285.85, Dc = 2.018 g·cm–3, m = 2.10 mm–1, F（000） = 584, GOOF = 1.025, the final R = 0.0515 and wR = 0.2125 for 1404 observed reflections（I 〉 2s（I））. The crystal structure is assembled by a slightly distorted {NiNO5} octahedral geometry and hydrogen bonds viz. N–H…O, O–H…O, C–O…π and π···π weak interactions. A rare π···π interaction from triazolate and carboxylate is affirmed through the molecular orbitals（MO） of three adjacent Ni CN molecules. The 3D Hirshfeld surface analysis was employed to gain additional insight into the interactions responsible for the packing of compound 1. Quantitative examination of 2D fingerprint plots revealed, amongst others, the dominating participation of O···H, N···H and π···π interactions in the molecular packing.

Synthesis, Characterization and Theoretical Studies of a Novel Salt(Dexmedetomidine: Perchloric Acid = 1:1) and the Investigation of Its Stability

Dexmedetomidine and its novel salt have been synthesized and characterized by single-crystal XRD and TGA/DSG. Components of the crystalline phase have also been investigated in terms of their corresponding Hirshfeld surface. In the crystal lattice, a three-dimensional hydrogen-bonded network is observed. In this work, the salt strategy has been applied successfully to dexmedetomidine. One important parameter, i.e. stability, has also been significantly improved, which proves to be an important factor for solid dosage formulation. Furthermore, DSC/TGA analysis indicates that the salt maintains its crystallinity up to 300℃, suggesting a higher stability of the salt compared to pure dexmedetomidine.

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.

Hydrothermal Synthesis, Structural Investigation and Characterization of an Organic-inorganic Hybrid, [Co(BⅡM)_3]_2H[BW_(12)O_(40)]·7H_2O

An organic-inorganic hybrid based on a-Keggin-typed [BWI2040]5- anionic cluster, [Co（BIIM）3]2H[BWx2040]＇7H20 （BIIM = 2,2＂-biimidazole）, was hydrothermally synthesized and structurally characterized by thermogravimetric analysis, IR and UV spectra. The title compound crystallizes in monoclinic, space group P21/n with a = 12.3490（10）, b = 33.270（3）, c = 18.9660（16） A, β = 105.9950（10）°, V= 7490.5（11） A3, C36HsoBCo2N24047W12, Mr = 3905.80, Dc = 3.45 l g/cm3, μ（MoKa） = 18.886 rnm-1, F（000） = 6972, Z = 4, S = 1.004, the final R = 0.0404 and wR = 0.0914 for 14683 observed reflections （1 〉 2tr（/））. The compound consists of two isolated [Co（BIIM）3]2＋ cations and one [BW12040]5 anion, in which each Co2＋ ion is coordinated by six N atoms from three BIIM ligands displaying a regular CoN6 octahedron. These components are finally linked together via N-H...O（polyoxometalate and wate） hydrogen bonds into a two-dimensional framework. Full investigation of the intermolecular interactions by Hirshfeld surface and fingerprint plots clearly indicates that there are rare W--Oterminal···πimidazole ring interactions which cooperate with the classical N-H···O hydrogen bonds to stabilize the structural packing.