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In this work, two new single crystals of copper-tetraphenylporphine (Cu-TPP) (crystals 2 and 3), which were induced by external magnetic fields with strengths of 0.5 and 0.8 T, respectively, have been prepared and characterized by single-crystal X-ray diffraction and Hirshfeld surface analysis. Compared with the original Cu-TPP (crystal 1), crystals 2 and 3 exhibit significant differences in their unit cell parameters, crystalline stacking styles and intermolecular interactions, resulting in a “compressed” crystal packing. Here, the number of closer interactions (H…H, C…H/H…C) increased with the magnetic field strength, accompanied by a decrease in the number of π…π (C…C) interactions as a sacrifice. On considering the results of our previous work, the results here suggest that a magnetic field has a different influence on the crystallization process of mono-component and multi-component materials, which will certainly provide some suggestions for the design of crystallization strategies for other materials with the presence of an external magnetic field. [ABSTRACT FROM AUTHOR]

In order to determine the effect of halogen bonding on supramolecular assemblies and photophysical properties of diaryl oxalates, diaryl oxalate itself and its derivatives with fluorine, chlorine, bromine, and iodine substituents in the p-position of phenyl rings were studied and compared. Their single-crystal structures were studied by geometrical analysis and theoretical calculation. The study reveals that different halogen bonds are formed with respect to different halogen atoms, such as C...F and X...X (bromine and iodine atoms) interactions, and molecular stacking modes would be affected by halogen bonds directly. Comparative studies of photophysical properties in dilute solution and solid state indicate that halogen substitutions would not affect the emission processes of diaryl oxalates in dilute solution; this is not the case for their solid state. This work has demonstrated that halogen bonds play an important role in regulating structures and photophysical properties of diaryl oxalates. [ABSTRACT FROM AUTHOR]

An investigation into the effect of switching methoxy and hydroxyl groups on molecular salts is presented in this study. The salts HL1+·NO3− (1), L1·HL1+·ClO4− (2), L1·HL1+·H2PO4−·H2O (3), HL2+·NO3− (4), HL2+·ClO4− (5) and HL2+·H2PO4− (6) were synthesized and structurally characterized. The study was carried out by analyzing the crystal structure, properties and intermolecular interactions within each of the salts using IR and fluorescence spectra, TGA, Hirshfeld surface analyses and π…π stacking motifs. Salt 1 has a layered structure, while 4 has a distorted 3-D structure. Salt 2 possesses an edge-to-face type plane interaction, while 5 is formed with a twisted structure. It is important to note that water molecules play a key role in the 1-D chain structure of salt 3. The π…π stacking motif of salts 1–3 have a herringbone structure, while salts 3–6 exhibit a γ-structure. In addition, the competitive crystallization of the synthetic salts was investigated and found to be consistent with the measured solubility. [ABSTRACT FROM AUTHOR]

Two complexes 1 [Cu(L1)2(H2O)2]·2H2O and 2 [Co(L2)2 (H2O)4]·4H2O formed by hetero N- and O-donor ligands 1-methyl-3-imidazole-4-carboxylic acid (L1H) and 2-methyl-5-pyridine carboxylic acid (L2H) have been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. These two complexes consist of a 2:1 ratio of ligand to metal ion. The analysis of Hirshfeld surfaces and crystal structures reveal that O‒H···O hydrogen bond interactions and C‒H···π intermolecular interactions support the three-dimensional supramolecular structures of complexes 1 and 2. Meanwhile, the coordinated water molecules and lattice water molecules play a key role in the construction of their crystal structures. [ABSTRACT FROM AUTHOR]

Three diaryl oxalate derivatives, bis(4-chlorophenyl)oxalate, bis(2, 6-dichlorophenyl)oxalate and bis(2, 4, 6-trichlorophenyl)oxalate, have been synthesized and characterized via X-ray single crystal diffraction, differential scanning calorimetry, thermogravimetric analysis and infrared spectra, for the purpose of studying the influence of chlorine substitution on the crystal structures of diaryl oxalate. This work has demonstrated that, depending on the position and number, chlorine substitution will influence the molecular geometries and stacking modes of diaryl oxalate by tuning the types and numbers of intermolecular interactions. [ABSTRACT FROM AUTHOR]

Two new mononuclear iron (II) coordination complexes: Fe(L1)2(SCN)2(1, L1:5-dimethylether-4-(4-methylphenyl)-3-(2-pyridinyl)-1,2,4-triazole) and Fe(L2)3(ClO4)2(2, L2:1-ethyl acetate-2-(2-pyridinyl)-imidazole), for the exploration of spin-crossover compounds have been synthesized and characterized. Structural analysis revealed that the framework of complex1is featured with 1-D chain structure connected by weak π···π interactions between the adjacent L1ligands, while complex2featured with various kinds of weak intermolecular hydrogen bonding interactions between Fe(L2)32+cation and ClO4−anion, which lead to a close crystal packing. The intermolecular interactions have shown a significant influence on the physical properties, and magnetic measurements of complexes1and2in the solid state at the room temperature revealed that the weak intermolecular interactions in1resulted in HS (high-spin) state, while the strong interactions in2lead to LS (low-spin) state over the whole temperature range. [ABSTRACT FROM PUBLISHER]

Two iso-structural two-dimensional (2D) porous coordination polymers, which formulated as [Fe(1,3-di(4-pyridyl)propane) 2 (NCX) 2 ] 2 (X = S [ 1 ], Se [ 2 ]) and featured 2-fold interpenetration, have been synthesised and characterized. Crystal structure, Hirshfeld surfaces analysis and magnetic properties of them were described. The basic-unit of 1 and 2 was the 2D rhombic grids [2 × (4, 4)] network, and the intermolecular interactions in the crystals were dominated by C–H…π, H–H and C–H…S (Se) contacts. The stronger ligand field strength of SeCN − than that of SCN − resulted to different magnetic properties: compound 1 shows paramagnetic property while 2 display displays an incomplete SCO transition approximately 30% conversion of high-spin (HS) to low-spin iron(II) sites with transition temperature of 100 K. [ABSTRACT FROM AUTHOR]

A series of Fe(II) complexes with (ClO4)−(SeCN)−, (ClO4)−(SCN)−, (Fe2OCl6)2−, and 2(BF4)−counter-anions for complexes1–4, derived from dmbpy (4,4′-dimethyl-2,2′-bipyridine), were prepared. The single-crystal studies and the Hirshfeld surfaces analysis revealed that the (Fe2OCl6)2−anion results more distortional octahedral geometry of the cation than other anions. In particular, the (ClO4)−(SCN)−and (Fe2OCl6)2−anions lead to complexes2and3stabilized via C-H···π interactions and π···π interactions, which were not found in the other two complexes. However, the double-chain structure of complex4was formed by C-H···F and C-H···C hydrogen bonds interactions. Due to the influence of different anions, magnetic susceptibility measurements showed that complex1was in high-spin (HS) state and complex2was in low-spin (LS) state. [ABSTRACT FROM PUBLISHER]

2,3-Dimethylpyrazine and 1,2-bis(4-pyridyl)ethane are both N-containing aromatic heterocyclics with two N atoms approximately in the para position. We here report two compounds derived from these heterocyclics (compounds 1 and 2). Compounds 1 and 2 both form a 1:1 2,3-dimethylpyrazine:perchloric acid (PA) and 1,2-bis(4-pyridyl)ethane:PA cocrystal, respectively. Their crystal structures were characterized by single-crystal X-ray diffraction, which revealed that the C-H⋯O and N-H⋯O hydrogen bonding interactions were found to stabilize the crystal structure in compounds 1 and 2. However, PA plays a necessary role for the one-dimensional structure in 1 and the three-dimensional structure in 2. Hirshfeld surfaces and fingerprint plots were applied to get the same conclusion. [ABSTRACT FROM AUTHOR]

Crystal structural investigations and Hirshfeld surface analysis of three methoxy- and methyl-substituted indole-3-acetonitriles (IAN) (4-OCH-IAN, 5-OCH-IAN and 7-CH-IAN) are reported in this work. Their structures were characterized by infrared spectra, elemental analyses, NMR spectra, differential scanning calorimetry, thermogravimetric analyses, and hot stage microscopy. The Hirshfeld surface analysis in terms of intermolecular interactions and π···π stacking motifs of the three substituted IANs was investigated in detail, and the results revealed that the different kinds of substituent groups as well as different substituted positions have a significant effect on the crystal structures, molecular π···π stacking motifs, melting points, and the types of intermolecular interactions. [ABSTRACT FROM AUTHOR]

We here reported a series of co-crystal structure of pyrazinamide (PZA) with m-hydroxybenzoic acid (MHBA), p-hydroxybenzoic acid (PHBA) and 3,4-dihydroxy benzolic acid (3,4-DHBA) and obtained three co-crystals (co-crystal 1- 3, respectively) under the same conditions. These crystal structures were characterized by single-crystal X-ray diffraction, IR spectra, thermogravimetric analyses, differential scanning calorimetry, and Raman spectrum analysis. The images of single crystal diffraction revealed that 1 was a 1:1 (PZA:MHBA) co-crystal, 2 was a 1:1 (PZA:PHBA) co-crystal, and 3 was a 1:1 (PZA:3,4-DHBA). The strong O-H···O, N-H···O hydrogen bonding interactions between PZA and hydroxyl-substituted benzoic acid primarily made the structure of co-crystals stabilized. Hirshfeld surface and fingerprint plots of the three co-crystals showed that the structures were stabilized by H···H, O-H···O, N-H···O C-H···π, and π···π intermolecular interactions. [ABSTRACT FROM AUTHOR]

Guest molecule dependent crystal structures, intermolecular interactions and magnetic properties of an iron (II) coordination polymer ( 2 ) with 4,4′-dipyridyl disulfide (4-DPS) ligand have been investigated. Polymer 2 {[Fe(NCS) 2 (4-PDS) 2 ]·2(2,5-DCP)} n was derived from polymer 1 [Fe(NCS) 2 (4-PDS) 2 ·4H 2 O] n through the change of water molecules by 2,5-dichloropyrazine molecules (2,5-DCP). This substitution leads to the change of the polymer motif from di -triangle to rectangle, and the decrease of longer contacts (S–H, N–H, C–H and H–H) while increase of the π ⋯ π (C–C) contacts in the crystal. These above changes then tuned the electronic structure of the iron (II) ion from high spin (HS) state ( 1 ) to the onset high spin (HS)–low spin (LS) transition ( 2 ), and resulted intermolecular anti-ferromagnetic interactions at lower temperatures. [ABSTRACT FROM AUTHOR]

Crystal structural investigations and Hirshfeld surface analysis of three halogen atoms (4-Cl, 6-Cl and 4-Br) substituted indole-3-acetonitrile (IAN) were reported in this work. The structures of the present three compounds were characterized by Infrared spectra, Elemental analyses, NMR spectra, differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) and hot stage microscopy (HSM). The Hirshfeld surfaces analysis in terms of crystal structure, intermolecular interactions and π⋯π stacking motifs were performed. We found that the different kinds of halogen atoms and the different substituted positions have a significant effect on the crystal structures, molecular π⋯π stacking motifs, melting points, and the nature of intermolecular interactions for IANs. [ABSTRACT FROM AUTHOR]

Four new complexes based on the 4-(4-carboxyphenyl)-1,2,4-triazole (Hcpt) ligand, {[Co(cpt) 2 (H 2 O) 4 ]·H 2 O}( 1 ), {[Cr(cpt) 2 (H 2 O) 4 ]·10H 2 O}( 2 ), {[Fe(cpt) 2 (H 2 O) 4 ]·10H 2 O}( 3 ), {[Zn(cpt) 2 (H 2 O) 2 ]}( 4 ) have been synthesized and characterized by elemental analysis, single crystal X-ray diffraction and TGA. For complexes 1 , 2 , and 3 , they almost have the same coordination mode that only one nitrogen atom of triazole are involved in the coordination, while in the complex 4 , only the group COO − participates in the coordination. In the crystal structure of 1 , each structural unit[Co(cpt) 2 (H 2 O) 4 ] is linked to another by hydrogen bonding formed by the lattice water molecules, thus forming a one-dimensional chain structure; In the crystal structure of 2 or 3, each structural unit[Cr(cpt) 2 (H 2 O) 4 ] or [Fe(cpt) 2 (H 2 O) 4 ] forms a two-dimensional layered structure by intermolecular hydrogen bonds from the coordinated water molecule and the group COO − . The results of thermogravimetric analysis show that the loss of lattice water and coordinated water molecules in 1 , 2 and 3 is below 120 °C, while the loss of coordinated water molecules in 4 is in the temperature range of 190–260 °C. Hirshfeld surface shows that the N H⋯O hydrogen bonding interaction plays a significant role towards the conformation of the basic structure of these complexes. [ABSTRACT FROM AUTHOR]

• Establishing a set of models of supramolecular complexes to further study substituent effect on the formation process of co-crystals. • Providing a widely applicable method for modifying industrial raw materials, finished products and auxiliary products. • Co-crystal strategy has been proven to be effective in the field of Spice Modification, improving the stability and release characteristics of traditional flavoring agents. Co-crystallizations of 2,3,5,6-tetramethyl pyrazin (TMP) with different substituted aromatic compounds [3,5-dinitrosalicylic acid (DNS), 5-chlorosalicylic acid (CSA) and 3,5-dichlorosalicylic acid (DCA)] have been performed, resulting in the formation of three co-crystals (TMP : DNS = 1:1 for 1 ; TMP : CSA = 1:2 for 2 ; TMP : DCA = 1:2 for 3). Those newly co-crystals were characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analyses (TGA), UV–Vis spectroscopy and X-ray diffraction (XRD). The Hirshfeld surface analysis revealed that N–H∙∙∙O/O–H∙∙∙N strong hydrogen bonds and other intermolecular interactions such as H∙∙∙H, C–H∙∙∙π, π∙∙∙π and lone-pair∙∙∙π participated in a cooperative way to stabilize the supramolecular structures. Additionally, thermodynamic results indicated that the halogen bonding exerted a positive effect on the stability of co-crystal structures, further improving the release process of pyrazine spices. This work provided a co-crystal strategy for the solidification of liquid pyrazine-related spices for broader applications. [Display omitted] [ABSTRACT FROM AUTHOR]

A new complex of the title system ([2(H 3 O + )·18-crown-6]·2[BF 4 − ]), which was induced by external magnetic field, has been prepared and characterized. When compared with other two members of the same system, the proton transfer induced by magnetic field from HBF 4 to H 2 O has leads to the co-plane of six oxygen atoms in the crown and stronger H F and O F intermolecular interactions, which can be attributed to the closer contacts between 18-crown-6, oxonium ion H 3 O + and counterion BF 4 − . In addition, a compression effect of crystals stacking has been observed. These results are of importance for the evaluation the effect of magnetic field on the host–guest systems. [ABSTRACT FROM AUTHOR]

Two zinc (II) pseudo-halide complexes [Zn( L 1 )(N 3 ) 2 ] n ( 1 L 1 : 1,2-diaminocyclohexane) and Zn( L 2 ) 2 (N 3 ) 2 ( 2 L 2 : 4,5-dimethy-2-(pyridine-2-yl) imidazole) have been synthesized and characterized. Single-crystal X-ray structural analysis revealed that the central Zn II atoms in 1 displays distorted trigonal bipyramidal arrangement with a 1D chain structure bridged by N 3 − anions, while in 2 , the central Zn II atoms incorporating with two bidentate L 2 ligands, and adopts an octahedral geometry and shows a “butterfly” coordination framework. Structural analysis demonstrated that the organic ligands play an important role in determining the resultant structure. In addition, both complexes were further characterized by thermal stability properties and Hirshfeld surface analysis. [ABSTRACT FROM AUTHOR]

Fluorescent materials have many interesting applications, but it remains difficult to control the luminescence of organic materials and in particular to retain the same luminescence in solution and in the solid state, a property of interest for various imaging applications. In this work, the influence of inorganic-anions on the crystal structure and physical–chemical properties of a series organic salts L + Cl − ( 1 ), L + ClO 4 − ( 2 ), L + NO 3 − ·H 2 O ( 3 ), 2 L + SO 4 2− ·2H 2 O ( 4 ) ( L = 4-[(4H-1,2,4-triazol-4-ylimino)methyl]phenol) has been investigated. Single crystal X-ray analyzes revealed that salt 1 formed a linear structure connected by H⋯O interactions, while salts 2 – 4 all formed 2D network structures through O⋯O interactions. The protonated L + s adopt face-to-face slipped π-stacked arrangement in salts 1 and 3 , while display monomer arrangements in 2 and 4 , the latter can be attribute to the entrapment of heavy anions in the crystal lattices. Optical-properties measurements of these four salts have shown L + arrangements dependent on solid-state properties: salt 1 and 3 show broad emission bands ( λ 1 = 478 nm, λ 2 = 487 nm) with a red shift of about 60 nm relative to its fluorescence in solvents, while 2 and 4 are similar to each other, exhibiting sharp bands ( λ 3 = 453 nm, λ 2 = 433 nm) with the higher ϕ PL values ( ϕ PL1 = 0.08, ϕ PL1 = 0.15, ϕ PL1 = 0.06, ϕ PL1 = 0.14). These results demonstrated the significant influence of inorganic-anions on the organic salts and the optical properties of organic materials could be modulated by entrapping different anions in lattice. [ABSTRACT FROM AUTHOR]

In the present study, the assembly of 6-aminonicotinic acid with inorganic acids (HBr, HNO 3 and H 3 PO 4 ) has been performed, which resulted in the molecular salts C 6 H 7 N 2 O 2 + ·Br − ( 1 ), C 6 H 7 N 2 O 2 + ·NO 3 − ( 2 ) and C 6 H 7 N 2 O 2 + ·H 2 PO 4 − ( 3 ), respectively. These three molecular salts have been characterized by single-crystal X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) and UV–Vis absorption spectroscopy (UV). The results revealed that molecular salt 1 exhibits an infinite 1-D chain structure stabilized mainly by N–H⋯Br contacts, while 2 and 3 show a 2-D network and a 3-D stereoscopic framework, respectively, which are stabilized mainly by strong N–H⋯O hydrogen bonding contacts. Hirshfeld surface analysis demonstrated the presence of H⋯H, O–H⋯N, C–H⋯π and π⋯π intermolecular interactions. In addition, the UV–Vis spectra exhibit a slight blue-shift to a shorter wavelength, which suggests the clear influence of the inorganic anions. [ABSTRACT FROM AUTHOR]

Four new complexes, [Co(dmbpy) 2 (dca) 2 ]·CH 3 OH ( 1 ), [Ni(dmbpy) 2 (dca) 2 ]·CH 3 OH ( 2 ), [Zn(dmbpy) 2 (dca) 2 ]·( 3 ) and [Cu(dmbpy) 2 (OH) 2 ]·5H 2 O ( 4 ) (dca = dicyanamide), derived from 4,4′-dimethyl-2,2′-bipyridine (dmbpy) have been synthesized and characterized by elemental analysis, TGA and single-crystal X-ray diffraction. Crystal structures and Hirshfeld surfaces analysis revealed that the complexes 1 – 3 were mainly supported by O H ⋯ N, C H ⋯ N and π ⋯ π intermolecular interactions, and for complex 4 , the uncoordinated water molecules play a key role in the construction of the 3D stacking motif. UV spectrum measurements demonstrate that all of the complexes show typical metal to ligand charge transfer (MLCT) absorption bands between 301 and 306 nm. Moreover, after complexation, the absorption maximum bands about intraligand π → π* transitions similarly show slightly red shift compared to dmbpy ligand, consisting with the DFT calculations. [ABSTRACT FROM AUTHOR]