Crystals Of Adduct Research Articles

Visible Light-Responsive Crystalline B←N Host Adducts with Solvent-Induced Allosteric Effect for Guest Release.

Photo-responsive organic crystals, capable of converting light energy into chemical energy to initiate conformational transitions, present an emerging strategy for developing lightweight and versatile smart materials. However, visible light-triggered tailored guests capture and release behaviors in all-organic solids are rarely reported. Here, we introduce a photoreactive crystalline boron-nitrogen (B←N) host adduct with the ability to undergo [2+2] photocycloaddition upon 447 nm light exposure. This process facilitates single-crystal-to-single-crystal (SCSC) photodimerization in the mother liquor, maintaining the original B←N host structure. Weakened intermolecular interactions within the photodimer host contribute to fast guest release in air under irradiation. Furthermore, the dynamic B←N bonds enable reversible transformations between organic host adducts and adduct cocrystals under the solvent-induced allosteric effect. As a result, four B←N host adduct crystals containing individual alkane guest are easily obtained and exhibited the ability of photo-controlled alkane release. Therefore, the integration of photo reactivity and structural transformation within B←N host adduct enables customized capture and release of guest molecules.

Visible Light‐Responsive Crystalline B←N Host Adducts with Solvent‐Induced Allosteric Effect for Guest Release

AbstractPhoto‐responsive organic crystals, capable of converting light energy into chemical energy to initiate conformational transitions, present an emerging strategy for developing lightweight and versatile smart materials. However, visible light‐triggered tailored guests capture and release behaviors in all‐organic solids are rarely reported. Here, we introduce a photoreactive crystalline boron‐nitrogen (B←N) host adduct with the ability to undergo [2+2] photocycloaddition upon 447 nm light exposure. This process facilitates single‐crystal‐to‐single‐crystal (SCSC) photodimerization in the mother liquor, maintaining the original B←N host structure. Weakened intermolecular interactions within the photodimer host contribute to fast guest release in air under irradiation. Furthermore, the dynamic B←N bonds enable reversible transformations between organic host adducts and adduct cocrystals under the solvent‐induced allosteric effect. As a result, four B←N host adduct crystals containing individual alkane guest are easily obtained and exhibited the ability of photo‐controlled alkane release. Therefore, the integration of photo reactivity and structural transformation within B←N host adduct enables customized capture and release of guest molecules.

MOLECULAR STRUCTURE AND COMPUTATIONAL STUDIES OF 1,2–BIS(4-PYRIDYL)ETHANE: 2–NITROBENZENE–1,3,5–TRIOL: AN ORGANIC ADDUCT

The molecular adduct crystals of 1,2–bis(4-pyridyl)ethane:2–nitrobenzene–1,3,5–triol were synthesized by slow evaporation solution growth method at ambient temperature. The structure of molecular adduct crystal was validated by a Single crystal X-ray diffraction study and it manifests that the adduct crystal belongs to the o triclinic system with space group P1. Computational studies were carried out to understand the nature of the crystals. The various hydrogen bonding interactions were confirmed by Hirshfeld surface analysis.

Enantioselective synthesis of ammonium cations.

Control of molecular chirality is a fundamental challenge in organic synthesis. Whereas methods to construct carbon stereocentres enantioselectively are well established, routes to synthesize enriched heteroatomic stereocentres have garnered less attention1-5. Of those atoms commonly present in organic molecules, nitrogen is the most difficult to control stereochemically. Although a limited number of resolution processes have been demonstrated6-8, no general methodology exists to enantioselectively prepare a nitrogen stereocentre. Here we show that control of the chirality of ammonium cations is easily achieved through a supramolecular recognition process. By combining enantioselective ammonium recognition mediated by 1,1'-bi-2-naphthol scaffolds with conditions that allow the nitrogen stereocentre to racemize, chiral ammonium cations can be produced in excellent yields and selectivities. Mechanistic investigations demonstrate that, through a combination of solution and solid-phase recognition, a thermodynamically driven adductive crystallization process is responsible for the observed selectivity. Distinct from processes based on dynamic and kinetic resolution, which are under kinetic control, this allows for increased selectivity over time by a self-corrective process. The importance of nitrogen stereocentres can be revealed through a stereoselective supramolecular recognition, which is not possible with naturally occurring pseudoenantiomeric Cinchona alkaloids. With practical access to the enantiomeric forms of ammonium cations, this previously ignored stereocentre is now available to be explored.

Physico-chemical characterization and computational studies of a new organic adduct 3-amino-2-chloropyridine: Benzilic acid, crystal for third order harmonic generation

Single crystals of 3-amino-2-chloropyridine:benzilic acid, an organic adduct have been grown by slow evaporation technique successfully. The structure of the adduct was confirmed by single crystal X-ray diffraction studies. The presence of functional groups was identified by Fourier transform infrared (FT-IR) spectroscopy. UV–vis analysis was performed to study the optical properties of the organic crystal. The thermal property of the crystal was studied by thermogravimetry (TG) and differential thermal analysis (DTA). Hirshfeld surface analysis was carried out to explore various interatomic interactions. Density functional theory (DFT) with appropriate basis set was used to optimize the molecular geometry of the adduct in the ground state and to compute the first-order hyperpolarizability. Based on optimized ground state geometry, natural bond orbital (NBO) analysis was performed to study the donor-acceptor interactions and stability of the molecule arising from hyperconjugative interactions leading to charge delocalization. The HOMO-LUMO energy gap value also supports the optical activity in the adduct crystal. Non-linear refractive index (n2), absorption coefficient (β) and third order non-linear susceptibility (χ3) of the adduct were determined by Z-scan technique.

Structural characterization, computational and biological studies of a new third order NLO (1:1) organic adduct: 2-Aminopyrimidine: 3-nitrophthalic acid

A new 1:1 organic molecular adduct 2-aminopyrimidine: 3-nitrophthalic acid (APNP) was successfully synthesized and single crystals were grown by slow solvent evaporation technique at room temperature. The formation of the molecular adduct was confirmed by single crystal XRD analysis, which further reveals that the crystal belongs to the monoclinic crystal system with a centrosymmetric space group, P21/n. FT-IR spectrum was recorded to identify the functional groups present in the molecular adduct. The purity and stoichiometry of the molecular adduct were confirmed by CHN analysis. The presence of different kinds of protons and carbon atoms in the molecular adduct was confirmed by 1H and 13C NMR spectroscopic studies respectively. UV–Vis–NIR spectroscopic study was carried out to identify the transparency window of APNP crystal. The TG/DTA analyses were carried out simultaneously to establish the thermal stability of the adduct crystal. The computational studies including optimization of molecular geometry, natural bond orbital (NBO) and HOMO-LUMO analyses were performed by density functional theory at the B3LYP method at 6–21g basis set level using Gaussian 09 software. Hirshfeld surface analysis was carried out to know the influence of hydrogen bonding on the molecular properties of the adduct crystal. The third order nonlinear susceptibility of the APNP salt was established by the Z-Scan study. Moreover, the APNP crystal was subjected to antimicrobial activity against various bacterial and fungal species. In addition, the antioxidant activity of APNP adduct was evaluated by DPPH assay method.

The Puzzling Monopentamethylcyclopentadienyltitanium(III) Dichloride Reagent: Structure and Properties.

Following the track of the useful titanocene [Ti(η5-C5H5)2Cl] reagent in organic synthesis, the related half-sandwich titanium(III) derivatives [Ti(η5-C5R5)Cl2] are receiving increasing attention in radical chemistry of many catalyzed transformations. However, the structure of the active titanium(III) species remains unknown in the literature. Herein, we describe the synthesis, crystal structure, and electronic structure of titanium(III) aggregates of composition [{Ti(η5-C5Me5)Cl2} n]. The thermolysis of [Ti(η5-C5Me5)Cl2Me] (1) in benzene or hexane at 180 °C results in the clean formation of [{Ti(η5-C5Me5)Cl(μ-Cl)}2] (2), methane, and ethene. The treatment of 1 with excess pinacolborane in hexane at 65 °C leads to a mixture of 2 and the paramagnetic trimer [{Ti(η5-C5Me5)(μ-Cl)2}3] (3). The X-ray crystal structures of compounds 2 and 3 show Ti-Ti distances of 3.267(1) and 3.219(12) Å, respectively. Computational studies (CASPT2//CASSCF and BS DFT methods) for dimer 2 reveal a singlet ground state and a relatively large singlet-triplet energy gap. Nuclear magnetic resonance spectroscopy of 2 in aromatic hydrocarbon solutions and DFT calculations for several [{Ti(η5-C5Me5)Cl2} n] aggregates are consistent with the existence of an equilibrium between the diamagnetic dimer [{Ti(η5-C5Me5)Cl(μ-Cl)}2] and a paramagnetic tetramer [{Ti(η5-C5Me5)(μ-Cl)2}4] in solution. In contrast, complex 2 readily dissolves in tetrahydrofuran to give a green-blue solution from which blue crystals of the mononuclear adduct [Ti(η5-C5Me5)Cl2(thf)] (4) were grown.

In(iii)In(iii) short contacts: an unnoticed metallophilic interaction?

Based on structural evidence and a theoretical analysis, we report here the existence of close contacts between In(iii) centres in the crystals of Lewis acid-base adducts that show features of metallophilic interactions and are not present for the lighter elements of group 13.

Binary and ternary solid-liquid phase equilibrium for the systems formed by succinic acid, urea and diethylene glycol: Determination and modelling

In this work, the solid-liquid phase equilibrium for binary system of succinic acid+diethylene glycol at the temperatures ranging from (298.15 to 333.15)K and ternary system of (succinic acid+urea+diethylene glycol) at 298.15K, 313.15K and 333.15K was built by using the isothermal saturation method under atmospheric pressure (101.2kPa), and the solubilities were determined by a high-performance liquid chromatography. The solid-phases formed in the ternary system of ((succinic acid+urea+diethylene glycol)) were confirmed by Schreinemaker’s method of wet residue, which corresponded to urea, succinic acid, and adduct 2:1 urea-succinic acid (mole ratio). Three isothermal phase diagrams for the ternary system were constructed based on the measured mutual solubility. Each isothermal phase diagram included six crystallization fields, three invariant curves, two invariant points and two co-saturated points. The crystalline region of adduct 2:1 urea-succinic acid is larger than those of the other two solids. The solubility of succinic acid in diethylene glycol was correlated with the modified Apelblat equation, λh equation and NRTL model; and the mutual solubility of the ternary ((succinic acid+urea+diethylene glycol)) system was correlated and calculated by the NRTL model. The interaction parameters’ values of succinic acid-urea were acquired. The value of RMSD was 7.11×10−3 for the ternary system. The calculation results had good agreement with the experiment values. Furthermore, the densities of equilibrium liquid phase were acquired. The phase diagrams and the thermodynamic model of the ternary system could provide the basis for design of the adductive crystallization process which was used to separate succinic acid with high purity from dicarboxylic acid mixtures.

Interaction of Ln3+ with Methyl-Substituted Cucurbit[n]urils (n=5,6) Derived from 3α-Methyl Glycoluril.

The interactions between a series of lanthanide cations (Ln3+ ) and methyl-substituted cucurbiturils (SPMeQ[5] and SHMeQ[6]) derived from a 3α-methyl glycoluril have been investigated. Single-crystal X-ray diffraction analysis revealed that both SPMeQ[5] and SHMeQ[6] selectively interact with certain lanthanide ions. SPMeQ[5] forms coordination capsules in the presence of [CdCl4 ]2- . The Ln3+ cations that interact are the four light lanthanides, La3+ , Ce3+ , Pr3+ , and Nd3+ , whereas the remaining lanthanide cations remain in solution. SHMeQ[6] formed adducts of SHMeQ[6] with aqua complexes of lanthanide cations ([Ln(H2 O)8 ]3+ ); for SHMeQ[6]-Ln(NO3 )3 -CdCl2 -HCl systems (Ln=Gd-Lu), no solid crystals were obtained from systems that contained La, Ce, Pr, Nd, Sm, or Eu. Whereas solid crystals of adducts of SHMeQ[6] with aqua complexes of lanthanide cations (Ln=Sm-Lu) formed SHMeQ[6]-Ln(NO3 )3 systems in neutral solution, no solid crystals were obtained from systems that contained La, Ce, Pr, or Nd. These results suggest that SPMeQ[5]- and SHMeQ[6]-Ln(NO3 )3 systems could be useful for the selective isolation of these lighter or heavier lanthanide cations from mixtures. Energy-dispersive spectrometry indicated that the lighter or heavier lanthanide cations could be isolated from their heavier or lighter counterparts through interaction with SPMeQ[5] and SHMeQ[6].

Synthesis, spectral, thermal, optical, electrical, mechanical and structural characterisations and quantum chemical study of 4-nitrophenol: Urea molecular adduct crystals

Organic non-linear single crystals of 4-Nitrophenol: Urea Adduct (NPUA) have been grown by slow evaporation-solution growth technique. The elemental analysis of the compound satisfies the stoichiometric expectations. Vibrational frequencies of the grown crystals have been identified by using FT-IR analysis. The presence of different protons and carbon atoms of the grown adduct was ascertained by 1H and 13C NMR analyses. The UV–Visible spectroscopy study revealed that the grown crystal has excellent transmittance and has wide band gap in the visible province. The fluorescence emission spectrum has also been recorded. Photoconductivity studies confirm positive photoconductivity nature of the crystals. The crystal belongs to the triclinic system with space group P1. The complete structural analysis of the grown crystal has been done using single crystal X-ray diffraction technique. Thermogravimetry (TG), Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC) were carried out to characterise the thermal behaviour and stability of NPUA. Dielectric studies have been carried out at room temperature. Mechanical behaviour of NPUA was studied by Vickers’s microhardness test. The nonlinear optical (NLO) activity test using a Q-switched and pulsed Nd: YAG laser confirms the generation of second harmonics. The Density Functional Theoretical (DFT) study affords further insight on the properties of the compound. Quantum Chemical Calculations (QCC) have been performed through DFT method at B3LYP/6-31G(d) level of theory. The optimised geometric parameters such as bond lengths, bond angles, dipole moment, optimisation energy and vibrational frequencies were reported and compared with the experimental data.

The synthesis, spectroscopy and X-ray single crystal structure of catena-[(μ-anacardato)-copper(ii)bipyridine][Cu2{(μ-O2CC6H3(o-OH)(o-C15H31)}4(NC5H5)2

Hydrogenation of crude anacardic acid gave a transparent crystalline product on recrystallization. When reacted with copper nitrate in the presence of pyridine it produced green crystals of a pyridine adduct of a dimeric copper(II) anacardate with the copper acetate structure. The X-ray single crystal structures of both anacardic acid and the copper complex were determined. Magnetic studies have confirmed strong antiferromagnetic coupling between copper(II) centre in the dimer. The exchange coupling constant was determined to be J = -324 cm(-1). The EPR spectra of the polycrystalline product are consistent with spin S = 1. The zero-field splitting parameter and g tensor values are |D| = 0.36 cm(-1), g(||) = 2.36 and g(⊥) = 2.06.

Thermodynamic Properties and Crystal Structures of the Adductive 2,6-Naphthalenedicarboxylic Acid Crystallization with N,N-Dimethyl Acetamide and N-Methyl Pyrrolidone

The crystal structures and thermodynamic properties of NDA-DMAC and NDA-NMP adduct crystals, the solubilities of 2,6-naphthalenedicarboxylic acid (NDA) in N,N-dimethyl acetamide (DMAC) and N-methyl pyrrolidone (NMP) over a temperature range from (293.2 to 373.2) K were studied in this paper. The results show that: (1) The asymmetric units of NDA-DMAC and NDA-NMP adduct crystals both contain one half molecule of NDA and one molecule of the solvent which are linked mainly by hydrogen bonds. (2) The thermal stabilities of the two adducts are both poor, and the initial dissociation temperature of NDA-DMAC and NDA-NMP adducts are about 306.29 K and 322.75 K, respectively. (3) The solubilities of NDA in DMAC and NMP solvents at (293.2 to 373.2) K both increase with the rise of experimental temperature. Below the dissociation temperature, the equilibrium solid phase is the adduct crystal with the adduct solvent. Otherwise, the equilibrium solid phase is the pure NDA solid with the adduct crystal dissociating. Th...

Crystallization and preliminary X-ray crystallographic analysis of ligand-free and arginine-bound forms ofThermotoga maritimaarginine-binding protein

The arginine-binding protein from Thermotoga maritima (TmArgBP) is an arginine-binding component of the ATP-binding cassette (ABC) transport system in this hyperthermophilic bacterium. This protein is endowed with an extraordinary stability towards thermal and chemical denaturation. Its structural characterization may provide useful insights for the clarification of structure-stability relationships and for the design of new biosensors. Crystallization trials were set up for both arginine-bound and ligand-free forms of TmArgBP and crystals suitable for crystallographic investigations were obtained for both forms. Ordered crystals of the arginine adduct of TmArgBP could only be obtained by using the detergent LDAO as an additive to the crystallization medium. These crystals were hexagonal, with unit-cell parameters a = 78.2, c = 434.7 Å, and diffracted to 2.7 Å resolution. The crystals of the ligand-free form were orthorhombic, with unit-cell parameters a = 51.8, b = 91.9, c = 117.9 Å, and diffracted to 2.25 Å resolution.

Thermodynamic Study on the Adduct Crystallization of Terephthalic Acid with Amides

The thermodynamics of adduct crystallization of terephthalic acid (TA) in amide solvents, such as N,N-dimethylacetamide (DMAC) and N-methyl-2-pyrrolidone (NMP), was studied in this paper. The results showed that the molecule ratio of TA and solvent in the TA-DMAC and TA-NMP adduct crystals is about 1:2. With poor thermal stability, the dissociation temperatures of the TA-DMAC and TA-NMP adduct crystals are about (341 and 313) K, respectively. The adduct crystallization is an exothermic process; the crystallization enthalpy of the [TA·2DMAC] adduct is about −34.00 kJ·mol−1, and that of the [TA·2NMP] adduct is about −31.12 kJ·mol−1. Finally, analysis of the liquid−solid equilibrium indicated that the concentration difference between the solubility of adduct crystals and the notional TA solid may result in the automatic adduct crystallization process.

Model development for deactivation of bisphenol-A adduct particles during crystallization under the influence of impurity

A deactivation mechanism was developed to present the influence of 4-tert-butylphenol as a sample impurity on the bisphenol-A (BPA) adduct particles during the crystallization process. 4-tert-butylphenol is an organic sample impurity generally present in the reaction mixture of the industrial production of BPA. Kinetic parameters of growth, nucleation, agglomeration, and deactivation were estimated using the technique of model fitting to experimental data. The population and mass balances were used to model the adductive crystallization of BPA. Experiments were carried out in several plastic bottles as crystallizers in a rotating bath. Liquid and solid phase information during the course of experiments was provided using the methods of gas chromatography, sieve analysis, and scanning electron microscopy. The impurity influence on the solution thermodynamics was investigated by measuring the width of metastable zone in the presence and in the absence of 4-tert-butylphenol. Consistency of the model predictions of size distributions with the experimental data beyond the range where the parameters were optimized revealed the validity of the model and the accuracy of the parameter values. The results showed that traces of impurity would reduce the BPA solubility, widen the metastability zone, increase agglomeration, and deactivate the growth and nucleation sites on the crystals.

Kinetic study of adductive crystallization of bisphenol-A

Kinetics of adductive crystallization of bisphenol-A (BPA) from a pure phenolic solution was investigated by model fitting to experimental data. BPA is an organic compound with vast applications in manufacturing of epoxy resins and polycarbonates; and adductive crystallization is used in industry to separate BPA from the reaction mixture of BPA synthesis. Using kinetic equations and mass and population balances the adductive crystallization process of BPA was modeled. Solid and liquid information was obtained from a set of crystallization experiments carried out under a cooling program. A genetic algorithm was applied to optimize the kinetic parameters of nucleation and growth rate equations. The nucleation rate equation for crystallization of BPA–phenol adduct from a pure synthetic solution was B 0 = 8.75 × 10 17 exp ( − 10900 / R T ) ( Δ C ) 2.8 M T 1.17 , where B 0 is the nucleation rate, Δ C is the supersaturation, and M T is the slurry density. The growth rate equation suggested was G = 5.72 × 10 13 exp(−10400/ RT)(Δ C) 2.7, where G is the growth rate of adduct particles. Fitting model predictions to experimental data demanded no addition of agglomeration terms to population balance equation which suggests an insignificant mechanism of agglomeration in particle enlargement. The nucleation and growth rate equations obtained in this study may be used to enhance the product quality of BPA plants.

Growth and Characterization of Urea Adduct with m-Nitrobenzoic Acid,m-Nitroaniline, and p-Xylene Mixtures

The urea adduct with the guests of m-nitrobenzoic acid, m-nitroaniline and p-xylene mixtures by adductive crystallization was successfully grown by slow evaporation method. The single crystals obtained were non-hygroscopic and good in size. The crystal structure of the grown crystal has been determined, and it belongs to the monoclinic system with centrosymmertic space group P21/c. Fourier transform infrared spectroscopic studies were performed for the identification of guest components in the compound. The optical absorption spectrum has been recorded in the range 200-1100 nm. The mechanical behavior of the specimen was studied.

Aluminum triiodide induced complexation and structural rearrangement of the hexaphospha–pentaprismane cage, P 6C 4tBu 4

Treatment of P 6C 4 t Bu 4 with the Lewis acid AlI 3 in toluene at room temperature unexpectedly results in a structural rearrangement affording the ionic complex [P 6C 4 t Bu 4H][AlI 4] which was fully characterized by multinuclear NMR spectroscopy and a single crystal X-ray diffraction study. Supportive evidence that the reaction might involve a simple intermediate Lewis acid–base adduct [AlI 3(η 1-P 6C 4 t Bu 4)] came from the isolation on one occasion of small number of crystals of the bis-Al adduct [{AlI 3}μ-{P 6C 4 t Bu 4}{AlI 3}], whose molecular structure was also confirmed by a single crystal X-ray diffraction study.

4,4′-Bipyridine–cyanoacetic acid (1/2)

Crystals of the title adduct, C10H8N2·2C3H3NO2, were obtained from a methanol/water solution of cyano­acetic acid and 4,4′-bipyridine at room temperature. In the crystal structure, cyano­acetic acid and centrosymmetric 4,4′-bipyridine mol­ecules are linked by O—H⋯N hydrogen bonds to form three-component supra­molecular adducts. The acidic H atom is almost midway between the O and N atoms of the cyano­acetic acid and bipyridine mol­ecules, with O—H and N—H distances of 1.19 (3) and 1.39 (3) Å, respectively, so that the H-atom transfer is best regarded as partial. The three-component adducts are further inter­connected with neighboring mol­ecules by weak inter­molecular C—H⋯O and C—H⋯N hydrogen bonds and by π–π stacking inter­actions [centroid–centroid distance = 3.7200 (11) Å] to generate a three-dimensional supra­molecular structure.