DMF Solvate Research Articles

In Situ X-Ray Techniques Unraveling Charge Distribution Induced by Halogen Bonds in Solvates of an Iodo-Substituted Squaraine Dye.

The importance of halogen bonds (XBs) in the regulation of material properties through a variation in the electrostatic potential of the halogen atom is not attracted much attention. Herein, this study utilizes in situ single crystal X-ray diffraction and synchrotron-based X-ray techniques to investigate the cooling-triggered irreversible single-crystal-to-single-crystal transformation of the DMF solvated iodo-substituted squaraine dye (SQD-I). Transformation is observed to be mediated by solvent-involved XB formation and strengthening of electrostatic interaction between adjacent SQD-I molecules. By immersing a DMF solvate in acetonitrile a solvent exchange without loss of long-range ordering is observed. This is attributed to conservation of the molecular charge distribution of SQD-I molecules during the process. The different solvates can be used in combination for temperature-dependent image encryption. This work emphasizes the changes caused by XB formation to the electrostatic potentials of halogen containing molecules and their influence on material properties and presents the potential utility of XBs in the design of soft-porous crystals and luminescent materials.

Crystal structure and Hirshfeld surface analysis of (E)-2-[2-(2-amino-1-cyano-2-oxoethylidene)hydrazin-1-yl]benzoic acid N,N-dimethylformamide monosolvate

In the title compound, C10H8N4O3·C3H7NO, the asymmetric unit contains two crystallographically independent molecules A and B, each of which has one DMF solvate molecule. Molecules A and B both feature intramolecular N—H...O hydrogen bonds, forming S(6) ring motifs and consolidating the molecular configuration. In the crystal, N—H...O and O—H...O hydrogen bonds connect molecules A and B, forming R 2 2(8) ring motifs. Weak C—H...O interactions link the molecules, forming layers parallel to the (\overline{2}12) plane. The DMF solvent molecules are also connected to the main molecules (A and B) by N—H...O hydrogen bonds. π–π stacking interactions [centroid-to-centroid distance = 3.8702 (17) Å] between the layers also increase the stability of the molecular structure in the third dimension. According to the Hirshfeld surface study, O...H/H...O interactions are the most significant contributors to the crystal packing (27.5% for molecule A and 25.1% for molecule B).

Thermal decomposition of DMSO or DMF solvates: an advanced method for obtaining new hybrid bismuth(iii) halides

Producing new hybrid halobismuthates by the thermal decomposition of corresponding solvates.

Exploring the thermal behaviour of the solvated structures of nifedipine.

Understanding the solvation and desolvation of pharmaceutical materials is an important part of materials discovery and development. In situ structural data are vital to understand the changes to crystal form that may occur in the system. In this study, the isolation and characterization of seven solvates of the L-type calcium channel antagonist, nifedipine, is described using variable-temperature powder X-ray diffraction so that the structural evolution as a function of temperature can be followed. The solvates reported herein can be split into those that are structurally similar to the previously reported dimethyl sulfoxide (DMSO) and dioxane solvates and those that have a novel packing arrangement. Of particular note is the solvate with tetrahydrofuran (THF) which has a hydrogen-bonding motif between the nifedipine molecules very similar to that of metastable β-nifedipine. In addition to variable-temperature X-ray diffraction, the stability of the solid forms was assessed using differential scanning calorimetry and thermogravimetric analysis and indicates that in all cases desolvation results in the thermodynamically stable α-polymorph of nifedipine even with the THF solvate. From the diffraction data the pathway of desolvation during heating of the DMF solvate showed conversion to another likely 1:1 polymorph before desolvation to α-nifedipine. The desolvation of this material indicated a two-stage process; first the initial loss of 90% of the solvent before the last 10% is lost on melting. The methanol solvate shows interesting negative thermal expansion on heating, which is rarely reported in organic materials, but this behaviour can be linked back to the winerack-type hydrogen-bonding pattern of the nifedipine molecules.

Structure, derivatisation, and metal complexation of p-cyclohexylcalix[4]arene

ABSTRACT Driven by an interest in the impact of the para-substituent of calix[4]arenes on metal complexation and structural chemistry, studies of p-cyclohexylcalix[4]arene (L) have been carried out. The 1:1 dichloromethane and dimethylformamide solvates were found to be isostructural, and different to the typical bilayer structure often observed for p-t-butylcalix[4]arene solvates. The methanol solvate, in contrast, does form a bilayered structure but is also a 1:1 solvate, unlike the p-t-butylcalix[4]arene·2MeOH system. Lanthanoid complexation was investigated, resulting in the structural characterisation of two different DMF solvates of a 2:2 dimeric europium complex, Eu2(L–3H)2(DMF)4. A tetrazole derivative, 5,11,17,23-tetracyclohexyl-25,27-dihydroxy-26,28-bis(tetrazole-5-ylmethoxy)calix[4]arene, has been synthesised via the intermediate 5,11,17,23-tetracyclohexyl-25,27-dihydroxy-26,28-dicyanomethoxycalix[4]arene, with the latter compound being structurally characterised. Attempts to isolate lanthanoid clusters supported by the tetrazole derivative under conditions known to form Ln19 clusters with the p-t-butyl analogue were unsuccessful, resulting only in isolation of the ligand from the reaction mixture.

Insights into the Mechanochemical Synthesis of MOF-74.

Mechanochemical synthesis has recently emerged as a scalable “green” approach for the preparation of MOFs, but current understanding of the underlying reaction mechanisms is limited. In this work, an investigation of the reaction pathway of the mechanochemical synthesis of MOF-74 from ZnO and 2,5-dihydroxyterephthalic acid (H4HDTA), using DMF as a liquid additive, is presented. The complex reaction pathway involves the formation of four short-lived intermediate phases, prior to the crystallization of MOF-74. The crystal structures of three of these intermediates have been determined using a combination of single-crystal and powder X-ray diffraction methods and are described here. The initial stages of the reaction are very fast, with a DMF solvate of H4HDTA forming after only 2 min of milling. This is followed by crystallization, after only 4 min of milling, of a triclinic one-dimensional coordination polymer, Zn(H2DHTA)(DMF)2(H2O)2, which converts into a monoclinic polymorph on additional milling. Highly crystalline MOF-74 appears after prolonged milling, for at least 70 min.

Synthesis, crystal structure, and supramolecular interactions in a bis(tetrachlorocatecholate) chelated manganese(III) complex

A mononuclear manganese(III) complex [DABH2][Mn2(Cl4Cat)2(H2O)2]·4DMF (1) (DAB = 1,4-diaminobutane, Cl4CatH2 = tetrachlorocatechol) is synthesized by a one-pot reaction involving manganese(II) chloride tetrahydrate and tetrachlorocatechol in a 1:2 molar ratio in the presence of 1,4-diaminobutane in a DMF-water mixture under aerobic conditions, and is structurally characterized. X-ray crystallography reveals that the complex anion is constructed with two tetrachlorocatecholate ligands coordinated to the manganese(III) center in equatorial positions, and two axial positions are occupied by two water molecules. The crystal packing of 1 is stabilized by complex networks of hydrogen bonding interactions in which oxygen atoms of coordinated tetrachlorocatecholate ligands and lattice DMF molecules serve as hydrogen bond acceptors, while the axially coordinated water molecules together with doubly protonated 1,4-diaminobutane act as hydrogen bond donors. The solid state packing of 1 is further stabilized by Cl⋯Cl halogen bonding interactions within tetracholorocatecholate units and the C—H⋯π and π⋯π interactions involving DMF solvates and aromatic rings of the tetracholorocatecholate ligands. The complex is further characterized by IR spectroscopy and cyclic voltammetry, and the results are analyzed.

Crystal Structure Characterization, Independent Gradient Model Analysis, and Gas‐Phase‐Mediated Transformation of Nicosulfuron DMF Solvate and Hydrate

AbstractThis review presents a comprehensive crystallographic study of nicosulfuron solvates and their transformation. N,N‐dimethylformamide solvate and hydrate are prepared and characterized by single‐crystal X‐ray diffraction. Although the crystal systems are different, their space conformations are quite similar. Independent gradient model simulation reveals that the nicosulfuron dimer structure is dominated by dispersion energy and the solvent molecules combine with the solute molecules by electrostatic energy. Dynamic vapor sorption is used for observation of the gas‐phase‐mediated transformation from the N,N‐dimethylformamide solvate to the hydrate, which is found to be dominated by the diffusion of water molecules and desorption of N,N‐dimethylformamide molecules.

An energetic derivative of 2,2′,4,4′,6,6′-hexanitrostilbene (HNS) and its DMF solvate crystallized from HNS solution with tertiary amine additives

ABSTRACTAn energetic derivative of 2,2′,4,4′,6,6′-hexanitrostilbene (HNS) and 2,4,7,9-tetranitro-10H-benzofuro[3,2-b]indole (TNBFI) has been synthesized from the N,N-dimethylformamide (DMF) solution of HNS with different tertiary amine additives, 4-(4-pyridyl)morpholine and 1,1-bis(morpholino) ethylene. TNBFI crystallized with DMF in a solvate, TNBFI·2DMF, was identified by negative ESI mass spectrum and single-crystal X-ray diffractions. The 3D-supermolecular structure of TNBFI·2DMF was built from the alternate stacking of TNBFI and DMF layers with π-stacking interactions between TNBFI molecules and H-bonding interactions between TNBFI and DMF molecules. The energetic properties of TNBFI molecule as well as the thermal stability of its DMF solvate have been investigated.

Four solid forms of filgotinib hydrochloride: Insight into the crystal structures, properties, stability, and solid-state transitions

Four solid forms of filgotinib hydrochloride were introduced in this study, including form A (trihydrate), form B (DMF solvate), form C (DMSO-water solvate) and form D (anhydrate). Single-crystal structures of the three pseudopolymorphs were elucidated by single-crystal X-ray diffraction. The results show that both form B and C are crystallized in the P‾1 space group with similar packing arrangement, while form A is in the P21/n space group. The host molecule conformations, H-bonding interactions, and packing arrangements of these single crystals were analyzed also. Besides, Hirshfeld surface analysis were used to compare the intermolecular interactions in these crystal structures. The properties of these solid forms were fully characterized by powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and Fourier transform infrared spectroscopy. The transformation relationship and the solid-state stability of all forms under different conditions were examined. Form A is proved to be the most stable form under normal storage conditions. However, solid-state transition experiment shows that it would transform to the corresponding solvate form under specific solvent atmosphere.

Pamoic acid-phenanthroline co-crystal and its Cu(II) complex: X-ray structures and luminescence properties

In this study, pamoic acid-phenanthroline proton transfer complex [(HPhen)(HPam)] and its Cu(II) complex {[Cu(Phen)2(H2O)2]Pam·2.5H2O were prepared and characterized by spectroscopic and analytical methods. The structures of the compounds were determined by single crystal X-ray diffraction studies. In the structure of the proton transfer complex [(HPhen)(HPam)], one of the carboxyl group proton of a pamoic acid molecule transferred to the one of phenanthroline nitrogen atom. In the structure, no hydrogen bond contacts were observed between the protonated phenanthroline (HPhen)+ and mono-deprotonated pamoic acid (HPam)- and phenanthroline (HPhen)+ cations involve in a hydrogen bond (N1-H····O7) with a DMF solvate. Hydrogen bonds between mono-deprotonated pamoic acid [HPam]- anions and π-π stacking interactions play a crucial role in the packing of the structure. X-ray crystallographic data showed that the Cu(II) complex consists of [Cu(Phen)2(H2O)2]2+ cationic unit, a pamoate counter anion and lattice water molecules (2.5H2O per complex cation). In the structure, each Cu(II) ion are six-coordinated and bound to four nitrogen atoms of two phenanthroline ligands and two water ligands with a distorted octahedral geometry. The pamoate anion does not involve in coordination with Cu(II) ion. The cationic units are linked by intermolecular hydrogen bonds forming a 2D hydrogen bond network. 2D hydrogen bond network further extended to 3D network by π-π stacking interactions. Absorption and emission spectral features of the compounds were investigated both in the solid state and solution.

Chalcogen bonding interactions in organic selenocyanates: from cooperativity to chelation

Organic selenocyanates form recurrent chain-like motifs ⋯Se(R)–CN⋯Se(R)–CN⋯ through short and linear chalcogen bonding Se⋯NC interactions. A chelating motif is also observed in a DMF solvate with two neighboring CH2–SeCN groups linked to the DMF oxygen atom.

Investigation of a solution‐mediated phase transformation of pranlukast DMF solvate to hemihydrate

Pranlukast is a potent selective cysteniyl leukotriene receptor antagonist to treat bronchial asthma and allergic rhinitis, which exists in several crystal forms. In this work, solution‐mediated phase transformation process from Pranlukast DMF solvate to the hemihydrate form was studied by using the focused beam reflectance measurement probe combined with powder X‐ray diffraction. The influence factors such as temperature, solvent composition, amount of added solid, and stirring rate were investigated. Results showed that higher temperature, larger mole fraction of water, lower amount of added solid, and faster stirring rate could accelerate the solution‐mediated phase transformation process.

Hybrid perovskite solar cells: In situ investigation of solution-processed PbI2 reveals metastable precursors and a pathway to producing porous thin films

Abstract

New insights into the coordination chemistry of Schiff bases derived from amino acids: Planar [Ni4] complexes with tyrosine side-chains

Structure and properties of a rare metal complex of the chiral Schiff base ligand derived from ortho-vanillin and L-tyrosine are presented. This study is a continuation of research on ligands containing biologically compatible moieties. The ligand is also fully characterized in form of a sodium salt, in particular in solution, for the first time. The metal complex contains a unique bowl-shaped [Ni4] core. Its structure is investigated both in solution (ESI-MS, NMR) and in solid state (X-ray diffraction studies). Under certain conditions the complex can be isolated as crystalline DMF solvate which is studied in solid state.

Crystal Structures and Vapor-Induced Crystalline Transformation of 7-Ethyl-10-Hydroxycamptothecin Pseudopolymorphs

Solvent-induced 3 frameworks (the monohydrate, methanol solvate, and dimethyl formamide [DMF] solvate) of an anticancer drug, 7-ethyl-10-hydroxycamptothecin (SN38), were constructed. The crystal structures of the 3 pseudopolymorphs were characterized by single-crystal X-ray diffraction technique for the first time. Crystal structure analysis of all these polymorphs revealed that the monohydrate showed 3D frameworks linked by hydrogen bonds. In the methanol solvate, the 1D molecular chains were linked by the methanol molecules through intermolecular hydrogen bonds to form a 2D sheet. The DMF solvate exhibits the 1D hydrogen bonding–linked chains along b-axis. Vapor-induced transformation has been investigated for the monohydrate, the methanol solvate, and the DMF solvate. The conversion relationships among the 3 solid frameworks are illustrated. Insights regarding transformation mechanisms have been established from consideration of the crystal structures.

Differential speciation of ferriprotoporphyrin IX in the presence of free base and diprotic 4-aminoquinoline antimalarial drugs

The crystal structures of the μ-propionato dimer and π–π dimer of ferriprotoporphyrin IX (Fe(III)PPIX) have been determined by single crystal X-ray diffraction (SCD). Both species were obtained in the presence of the synthetic 4-aminoquinoline antimalarial drug, amodiaquine (AQ). The solution that afforded the μ-propionato dimer contained AQ as a free base (i.e. with both quinoline and terminal amine nitrogen atoms neutral). On the other hand, when the diprotic salt of AQ was included in the crystallization medium, the Fe(III)PPIX π–π dimer was obtained. The structure of the μ-propionato dimer, which is the discrete structural unit that constitutes haemozoin (malaria pigment), is identical to that obtained previously in presence of chloroquine free base. We suspect that the drug, via its two available basic sites, facilitates dissociation of one of the two Fe(III)PPIX propionic acid groups to yield a propionate group that is required for reciprocal coordination of the metal centre to form the centrosymmetric dimer. On the other hand, this proton transfer is not possible when the drug is present as a diprotic salt. In this case, the π–π dimer of Fe(III)PPIX is obtained. In the current study, the π–π dimer of haemin (chloro-Fe(III)PPIX) was obtained as a DMF solvate from non-aqueous aprotic solution (dimethyl formamide and chloroform), however the π–π dimer is also known to exist in aqueous solution (as aqua- or hydroxo-Fe(III)PPIX), where it is purportedly involved in the nucleation of haemozoin. We have been able to unambiguously determine the positions of all non-hydrogen atoms, as well as locate or assign all hydrogen atoms in the structure of the π–π dimer, which was not possible in the SCD structure of haemin reported by Koenig in 1965 owing to disorder in the vinyl and methyl substituents. Interestingly, no disorder in the methyl and vinyl groups is observed in the current structure. Both the π–π and μ-propionato dimers of Fe(III)PPIX are important species in the haem detoxification pathway in the malaria parasite and other blood-feeding organisms, and the structural insight gained in this study may assist target-driven design of new chemotherapeutic agents.

Ln(III) metal-organic frameworks with 5-nitroisophthalate ligands: Crystal structures and luminescent properties

Two new Ln(III) metal-organic frameworks (MOFs) based on 5-nitroisophthalic acid (H2L), namely [Pr4(L)6(H2O)4]n (I) and [Gd(L)(FA)(H2O)2]n (II) (HFA = formic acid), were prepared by solvothermal reactions and structurally characterized by IR, elemental analysis, XRD, and single crystal X-ray diffraction (CIF files CCDC nos. 971379 (I) and 971380 (II)). A 3D {4.62}{410.617.89}{43}2 topology framework of I and a 3D {4.622}{42.610.83} topology network of II are constructed respectively with different synthetic conditions. Four kinds of coordination modes are observed for dicarboxylate in these two MOFs in total. Notably, the in situ hydrolysis of DMF solvates leads to the formation of formate ions that was observed in the structure of II. Moreover, the luminescent properties of both complexes and corresponding ligand have been investigated.

Thermodynamic Study of CO2 Sorption by Polymorphic Microporous MOFs with Open Zn(II) Coordination Sites.

Two Zn-based metal organic frameworks have been prepared solvothermally, and their selectivity for CO2 adsorption was investigated. In both frameworks, the inorganic structural building unit is composed of Zn(II) bridged by the 2-carboxylate or 5-carboxylate pendants of 2,5-pyridine dicarboxylate (pydc) to form a 1D zigzag chain. The zigzag chains are linked by the bridging 2,5-carboxylates across the Zn ions to form 3D networks with formulas of Zn4(pydc)4(DMF)2·3DMF (1) and Zn2(pydc)2(DEF) (2). The framework (1) contains coordinated DMF as well as DMF solvates (DMF = N,N-dimethylformamide), while (2) contains coordinated DEF (DEF = N,N-diethylformamide). (1) displays a reversible type-I sorption isotherm for CO2 and N2 with BET surface areas of 196 and 319 m(2)/g, respectively. At low pressures, CO2 and N2 isotherms for (2) were not able to reach saturation, indicative of pore sizes too small for the gas molecules to penetrate. A solvent exchange to give (2)-MeOH allowed for increased CO2 and N2 adsorption onto the MOF surface with BET surface areas of 41 and 39 m(2)/g, respectively. The binding of CO2 into the framework of (1) was found to be exothermic with a zero coverage heat of adsorption, Qst(0), of −27.7 kJ/mol. The Qst(0) of (2) and (2)-MeOH were found to be −3 and −41 kJ/mol, respectively. The CO2/N2 selectivity for (1), calculated from the estimated KH at 296 K, was found to be 42. At pressures relevant to postcombustion capture, the selectivity was 14. The thermodynamic data are consistent with a mechanism of adsorption that involves CO2 binding to the unsaturated Zn(II) metal centers present in the crystal structures.

Crystal Structure Analysis of Betti Base 1-((2-hydroxynaphthalen-1-yl)(2-hydroxyphenyl)methyl)urea•2DMF Solvate

A novel Betti base compound, 1-((2-hydroxynaphthalen-1-yl)(2-hydroxyphenyl)methyl)urea, UBB, was synthesized and characterized by spectral, structural and thermal studies. Single crystal X-ray diffraction studies reveal that the racemic mixture of the compound, when crystallized from DMF, yields R-isomer preferentially (prismatic crystals), whereas, when crystallized from 5:1 (v/v) mixture of DMF-THF, it yields S-isomer (rectangular shaped crystals) with two molecules of DMF, included in both the cases. The crystal structure is discussed in terms of supramolecular interactions and molecular modeling. Both R and S enantiomeric DMF solvate crystals are in their chiral triclinic P1 space group.