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Chengtian Zhang

Bio: Chengtian Zhang is an academic researcher. The author has contributed to research in topics: Crystal & Solubility. The author has an hindex of 1, co-authored 2 publications receiving 2 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors summarized the growth defects of organic crystals from four perspectives; formation mechanism, characterization methods, control methods, and applications, and concluded three kinds of formation mechanism which are related to diffusion of solute molecules, impurities participating in the crystal growth, and structure of solutes respectively.

11 citations

Journal ArticleDOI
TL;DR: In this paper, the authors presented the preparation of five new multicomponent crystals of 2,4-D, including three salts with imidazole (IMZ), 2-aminopyridine (AAP), and 3-amino-polycyclic acid (BAP) as coformers.
Abstract: 2,4-Dichlorophenoxyacetic acid (2,4-D) is a kind of plant growth regulator which exhibits hormesis effects at low dosages, while high dosages adversely affect the exposed organisms and act as herbicide. 2,4-D has low solubility, therefore, it is a good candidate for crystal engineering research to improve its solubility. This paper presents the preparation of five new multicomponent crystals of 2,4-D, including three salts with imidazole (IMZ), 2-aminopyridine (AAP), and 3-aminopyridine (BAP), and two cocrystals with isonicotinamide (ISO) and pyrazinamide (PYM) as coformers (CCFs). The five multicomponent crystals were first characterized by single-crystal X-ray diffraction, powder X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. Molecular interactions, crystal packing, and structure similarity analyses performed using Hirshfeld surface and CrystalCMP confirmed the charge-assisted H-bonding sites and structural similarity among the solved crystal structures. The stability tests show that all five multi-component crystals exhibit excellent stability within 12 weeks under accelerated storage conditions (40 °C and 75% RH). Moreover, all the five multicomponent crystals of 2,4-D exhibit increased solubility, especially (2,4-D)+(IMZ)− that increased the solubility of the resulting salt by 70 times compared to the free acid 2,4-D. From the perspective of single-crystal structure and intermolecular interaction, the reasons for these changes in physical and chemical properties are further clarified.

11 citations


Cited by
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01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

1,652 citations

Journal ArticleDOI
27 Jul 2022
TL;DR: In this article , the authors demonstrated various engineering defect strategies in graphitic carbon nitride (g-C3N4) to promote photocatalytic efficiency under solar energy.
Abstract: Excessive release of greenhouse gas carbon dioxide (CO2) into the atmosphere and continuous utilization of fossil fuels has resulted in global warming and energy shortage. Among the different alternatives, photocatalytic conversion of CO2 to fuels and hydrogen production is a promising approach. To achieve this goal, highly efficient and low-cost semiconductor are demanding to maximize solar energy conversion to renewable fuels. In this perspective, metal free two-dimensional (2D) graphitic carbon nitride (g-C3N4) has attracted numerous considerations because of its low cost and higher reduction potential, but it has a lower efficiency. Herein, we demonstrated various engineering defect strategies in g-C3N4 to promote photocatalytic efficiency under solar energy. Initially, an overview of engineering defects, creation of different vacancies in g-C3N4, and their identification is discussed. In the main stream defect, engineering such as carbon, nitrogen, and oxygen to promote g-C3N4 photocatalytic efficiency is systematically disclosed. Subsequently, the role of sulfur (S) and phosphorus (P) atoms in g-C3N4 to maximize CO2 reduction and hydrogen production are deliberated. The comparative analysis, efficiency enhancement, and role of defect engineering are finally discussed to get higher yields and productivities under solar energy utilization.

18 citations

Journal ArticleDOI
TL;DR: Selinger et al. as discussed by the authors reported a series of halogen-substituted benzil crystals showing elastic bending (within ∼2.45% strain), followed by elastoplastic deformation under ambient conditions.
Abstract: As an emerging class of flexible materials, mechanically bendable molecular crystals are broadly classified as elastic or plastic. Nevertheless, flexible organic crystals with mutually exclusive elastic and plastic traits, with contrasting structural requirements, co-existing under different stress settings are exceptional; hence, it is imperative to establish the concurring factors that beget this rare occurrence. We report a series of halogen-substituted benzil crystals showing elastic bending (within ∼2.45% strain), followed by elastoplastic deformation under ambient conditions. Under higher stress settings, they display exceptional plastic flexibility that one could bend, twist, or even coil around a capillary tube. X-ray diffraction, microscopy, and computational data reveal the microscopic and macroscopic basis for the exciting co-existence of elastic, elastoplastic, and plastic properties in the crystals. The layered molecular arrangement and the weak dispersive interactions sustaining the interlayer region provide considerable tolerance towards breaking and making upon engaging or releasing the external stress; it enables restoring the original state within the elastic strain. Comparative studies with oxalate compounds, wherein the twisted diketo moiety in benzil was replaced with a rigid and coplanar central oxalate moiety, enabled us to understand the effect of the anisotropy factor on the crystal packing induced by the C Created by potrace 1.16, written by Peter Selinger 2001-2019 O⋯C tetral interactions. The enhanced anisotropy depreciated the elastic domain, making the oxalate crystals more prone to plastic deformation. Three-point bending experiments and the determined Young's moduli further corroborate the co-existence of the elastic and plastic realm and highlight the critical role of the underlying structural elements that determine the elastic to plastic transformation. The work highlights the possible co-existence of orthogonal mechanical characteristics in molecular crystals and further construed the concurrent role of microscopic and macroscopic elements in attaining this exceptional mechanical trait.

8 citations

Journal ArticleDOI
TL;DR: In this paper , a hydrogen-bonded organic framework (MM•TPY) with hierarchical skeletal morphology, containing stable micro-and macroporosity, is presented, where the mechanism of assembly during the crystal formation is compatible with a skeletal crystal growth.
Abstract: Abstract Porous organic molecular materials represent an emergent field of research in Chemistry and Materials Science due to their unique combination of properties. To enhance their performance and expand the number of applications, the incorporation of hierarchical porosity is required, as exclusive microporosity entails several limitations. However, the integration of macropores in porous organic molecular materials is still an outstanding challenge. Herein, we report the first example of a hydrogen‐bonded organic framework (MM‐TPY) with hierarchical skeletal morphology, containing stable micro‐ and macroporosity. The crystal size, from micro to centimetre scale, can be controlled in a single step without using additives or templates. The mechanism of assembly during the crystal formation is compatible with a skeletal crystal growth. As proof of concept, we employed the hierarchical porosity as a platform for the dual, sequential and selective co‐recognition of molecular species and microparticles.

5 citations

Journal ArticleDOI
TL;DR: In this article , new multicomponent crystals of 2,4-D have been discovered by a combined virtual and experimental cocrystal, which is an herbicide and plant growth regulator widely applied in crop production.
Abstract: 2,4-Dichlorophenoxyacetic acid (2,4-D) is an herbicide and plant growth regulator widely applied in crop production. New multicomponent crystals of 2,4-D have been discovered by a combined virtual and experimental cocrystal...

5 citations