Cis And Trans Research Articles

Efficient E/Z conversion of (all-E)-lycopene to Z-isomers with a high proportion of (5Z)-lycopene by food grade plant extracts

The conversion of lycopene from natural sources, mainly in all trans configurations, to cis configuration means a significant increase in bioavailability. However, the existing isomerization methods have problems with residual organic solvents, which limits the use of products. such as metal ion catalysis, electrocatalysis, and iodine-doped titanium dioxide (I–TiO2) catalysis. In this paper, the effects of common plant extracts on lycopene isomerization and its stability were investigated. Among them, sulforaphane and allicin showed significant catalytic effects, with sulforaphane being the most effective. Therefore, Broccoli sprouts were selected as a food component to investigate the catalytic isomerization of lycopene. After the optimization of pretreatment, the final content of sulforaphane was 5.81 mg/g. The cis-proportion of lycopene was elevated from 5% in the blank group to more than 60% when the treated broccoli sprout paste was added to the tomato paste. Also, the bioavailability of lycopene increased significantly with the increase in cis proportion. Compared with other isomerization methods, the method studied in this paper does not require any organic reagents and only uses food-grade materials such as allicin, sulforaphane, and broccoli sprouts to catalyze the cis-trans isomerization of lycopene.

Stable 2-Azaallyl Salts as a Bridge between 2H-Azirines and Densely Functionalized 2H-Pyrroles.

An efficient protocol for the synthesis of stable 2-azaallyl anion salts by the reaction of alkyl 2-bromo-2H-azirine-2-carboxylates with trimethylsilyl cyanide/Bu4NF has been developed. The domino reaction proceeds in four steps via the cleavage of the azirine C-C bond to provide the tetrabutylammonium salts of stereochemically pure 2-azaallyl anions having U-configuration relative to the cyano groups. The anions with an ortho-substituted aryl group or styryl group exist as a mixture of two geometrical isomers across the N2-C3 bond. 2-Azaallyl anion salts have been shown to be convenient substrates for the one-pot synthesis of densely functionalized 2H-pyrroles by the alkylation-cyclization sequence.

Mechanochemical Synthesis of Chromium(III) Complexes Containing Bidentate PN and Tridentate P-NH-P and P-NH-P' Ligands.

Chromium(III) complexes bearing bidentate {NH2(CH2)2PPh2: PN, (S,S)-[NH2(CHPh)2PPh2]: P'N} and tridentate [Ph2P(CH2)2N(H)(CH2)2PPh2: P-NH-P, (S,S)-(iPr)2PCH2CH2N(H)CH(Ph)CH(Ph)PPh2: P-NH-P'] ligands have been synthesized using a mechanochemical approach. The complexes {cis-[Cr(PN)Cl2]Cl (1), cis-[Cr(P'N)Cl2]Cl (2), mer-Cr(P-NH-P)Cl3 (3), and mer-Cr(P-NH-P')Cl3 (4)} were obtained in high yield (95-97%) via the grinding of the respective ligands andthe solid Cr(III) ion precursor [CrCl3(THF)3] with the aid of a pestle and mortar, followed by recrystallization in acetonitrile. The isolated complexes are high spin. A single-crystal X-ray diffraction study of 2 revealed a cationic chromium complex with two P'N ligands in a cis configuration with P' trans to P' with chloride as the counteranion. The X-ray study of 4 shows a neutral Cr(III) complex with the P-NH-P' ligand in a mer configuration. The difference in molecular structures and bulkiness of the ligands influence the electronic, magnetic, and electrochemical properties of the complexes as exhibited by the bathochromic shifts in the electronic absorption peaks of the complexes and the relative increase in the magnetic moment of 3 (4.19 μβ) and 4 (4.15 μβ) above the spin only value (3.88 μβ) for a d3 electronic configuration. Complexes 1-4 were found to be inactive in the hydrogenation of an aldimine [(E)-1-(4-fluorophenyl)-N-phenylmethanimine] under a variety of activating conditions. The addition of magnesium and trimethylsilyl chloride in THF did cause hydrogenation at room temperature, but this occurred even in the absence of the chromium complex. The hydrogen in the amine product came from the THF solvent in this novel reaction, as determined by deuterium incorporation into the product when deuterated THF was used.

Synthesis, characterization, and antibacterial activity studies of two Co(II) complexes with 2-[(E)-(3-acetyl-4-hydroxyphenyl)diazenyl]-4-(2-hydroxyphenyl)thiophene-3-carboxylic acid as a ligand

Two new Cobalt(II) complexes 12 and 13 have been synthesized from 2-[(E)-(3-acetyl-4-hydroxyphenyl)diazenyl]-4-(2-hydroxyphenyl)thiophene-3-carboxylic acid (11) as a novel ligand. These three new compounds were characterized on the basis of their powder X-Ray Diffraction, UV–Vis, IR, NMR, elemental analysis and MS spectral data. DFT/B3LYP mode of calculations were carried out to determine some theorical parameters of the molecular structure of the ligand. The purity of the azoic ligand and the metal complexes were ascertained by TLC and melting points. The analysis of the IR spectra of the polyfunctionalized azo compound 11 and its metal complexes 12 and 13, reveals that the coordination patterns of the ligand are hexadentate and tetradentate respectively. Based on the UV–Vis electronic spectral data and relevant literature reports, the ligand and derived complexes were assigned the E (trans) isomer form. Likewise, octahedral and square-planar geometries were respectively assigned to the cobalt(II) complexes. The broth microdilution method was used for antibacterial assays through the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The ligand 11 displayed moderate antibacterial activity (MIC = 32–128 μg/mL) against Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922, Pseudomonas aeruginosa and Klebsiella pneumoniae 22. The octahedral cobalt(II) complex 12 showed moderate activity against Pseudomonas aeruginosa (MIC = 128 μg/mL) and Klebsiella pneumoniae 22 (MIC = 64 μg/mL) and none against Staphylococcus aureus ATCC25923 and Escherichia coli ATCC25922, whereas the square-planar complex 13 displayed moderate activity only on Klebsiella pneumoniae 22 (MIC = 64 μg/mL).Graphical abstract

Dual site reactivity of indole-3-Schiff bases with S/Se/Cl substituted ketenes for stereoselective C-4 substituted indole-β-lactams, biological evaluations, magic chloro effect and molecular docking studies

A convenient methodology for C-4 indole-β-lactam hybrids with chloro, sulphur and seleno substitutions through dual site reactivity of indole-3-Schiff bases towards ketenes has been developed. The reaction proceeded in a stereospecific manner with the exclusive formation of trans-β-lactams assigned with respect to C3-H and C4-H. The synthesized novel β-lactams have been characterized with the help of elemental analysis (CHNS) and spectroscopic techniques viz.1H NMR, 13C NMR, DEPT 135, HSQC and IR. The trans configuration was further estabilished based on X-ray crystallographic data. Examination of antibacterial properties unveiled that only derivatives 5a and 5b, featuring chloro substitution, exhibited potent activities, underscoring the emergence of the recently coined term “magic chloro effect”. Molecular docking analysis provided additional support for the observed in vitro antibacterial activities of compounds 5a-b.

Raman, ATRIR and NMR spectra, conformational stability, vibrational assignments, normal coordinates analysis and DFT calculations of hydrochlorothiazide drug

The Raman (4000-50 cm−1), attenuated total reflectance (ATR) infrared (4000-400 cm−1) spectra of Hydrochlorothiazide (C7H8ClN3O4S2; HCTZ) have been recorded in the solid state in addition to LCMS in the dimer and trimer ranges. The 1H, 13C and 15N NMR spectra were also recorded in addition to DEPT (45, 90 and 135) of HCTZ sample dissolved DMSO‑d6. Initially, three conformers resulting from the rotation of -SO2NH2 moiety around C9-S11 were proposed, namely gauche, trans and cis conformers. And then Density Functional Theory (DFT) calculations for an isolated molecule were carried out employing both B3LYP and P3PW91 methods at 6-31G(d), 6-311+G(d), 6–311++G(d,p) basis set. The cis isomer is a transition state owing to the prediction of an imaginary wavenumber, while the gauche being more stable than trans by ∼438–538 cm−1 (∼1.25–1.54 kcal) employing the afore-mentioned computations. Moreover, we carried out a potential surface scan for the gauche to determine SO2NH2 barriers to internal rotations and to ensure the optimal gauche is the most stable conformer. Aided by normal coordinate analysis (NCA) in addition to the atomic displacements in Cartesian coordinates (ADCC), confident vibrational assignment of the observed infrared and Raman bands are proposed for all fundamentals of the gauche rotamer. Nevertheless, force constants (FCs) in internal coordinates were also estimated using the above-mentioned methods and basis sets as well. The 1H, 13C and 15N chemical shifts were also correlated to their corresponding atoms. The results are reported herein and compared with HCTZ and its cocrystals whenever appropriate.

Two-Dimensional Projected-Momentum Covariance Mapping for Coulomb Explosion Imaging.

We introduce projected-momentum covariance mapping, an extension of recoil-frame covariance mapping for 2D ion imaging studies. By considering the two-dimensional projection of the ion momenta as recorded by the detector, one opens the door to a complex suite of analysis tools adapted from three-dimensional momentum imaging studies. This includes the use of different frames of reference to unravel the dynamics of fragmentation and the application of fragment momentum constraints to isolate specific fragmentation channels. The technique is demonstrated on data from a two-dimensional ion imaging study of the Coulomb explosion of the cis and trans isomers of 1,2-dichloroethene, following strong-field ionization by an intense near-infrared femtosecond laser pulse. Classical simulations are used to guide the interpretation of projected-momentum covariance maps. The results offer a detailed insight into the distinct Coulomb explosion dynamics for this pair of isomers and lay the groundwork for future time-resolved studies of photoisomerization dynamics in this molecular system.

Fused double oxazolidine vs Imine ligands and Zn-complexes formation: Experimental and theoretical calculations

The condensation reaction between minodiols and carboxaldehydes offers the possibility to obtain either 1-aza-3,7-dioxabicycle[3.3.0]octane (namely here as fused double oxazolidine) or imine compounds. Till now, only limited information is available regarding the factors influencing this behavior. Thus, the present work explored the substituent effect on the reactivity of aminodiols with pyridine carboxaldehydes both in the presence and absence of Zn (II). Without the presence of the metal, the condensation reactions favor the production of fused double oxazolidine derivatives, with identification of both cis and trans isomers in relation to the pyridyl moieties. Notably, the presence of a methyl substituent favors the trans isomers owing to the steric hindrance effect, while a hydrogen substituent favors the cis isomers. Conversely, in the presence of ZnCl2, the main product is the imine-metal complex when the substituent is a methyl group. However, in the presence of a hydrogen substituent, both the imine-metal and the fused double oxazolidine-metal complexes were produced as a mixture in similar proportions. These experimental results are supported by theoretical calculations.

Exploring the Impact of Linkage Structure in Ferroelectric Nematic and Smectic Liquid Crystals.

The liquid crystal molecule 3-fluoro-4-(3,4,5-trifluorophenyl)phenyl 2,6-difluoro-4-(trans-5-n-propyl-1,3-dioxane-2-yl)benzoate (DIO) has attracted considerable interest owing to its unique ferroelectric nematic phase and extraordinarily high dielectric constant. To expand the DIO series, novel analogs with 1,3-dioxane units converted to ester units (EST analogs) were synthesized, and their physical properties were characterized. The EST analogs exhibited ferroelectric phases similar to those of the corresponding DIO analogs. Interestingly, an EST analogue featuring a defluorinated benzoate unit exhibited a ferroelectric smectic A phase, despite its smaller longitudinal dipole moment of 6.9 D. This result diverges from the common knowledge that the formation of large longitudinal dipoles is traditionally effective in the emergence of ferroelectric phases. Unlike the DIO series, the EST analogs can be readily obtained without the formation of undesired geometric isomers, which is advantageous for practical applications. The results of this study provide valuable insights into the design of liquid-crystalline materials expressing ferroelectric phases.

Synthesis of 4'-Thionucleoside Analogues Bearing a C2' Stereogenic All-Carbon Quaternary Center.

The design of novel 4'-thionucleoside analogues bearing a C2' stereogenic all-carbon quaternary center is described. The synthesis involves a highly diastereoselective Mukaiyama aldol reaction, and a diastereoselective radical-based vinyl group transfer to generate the all-carbon stereogenic C2' center, along with different approaches to control the selectivity of the N-glycosidic bond. Intramolecular SN2-like cyclization of a mixture of acyclic thioaminals provided analogues with a pyrimidine nucleobase. A kinetic bias favoring cyclization of the 1',2'-anti thioaminal furnished the desired β-D-4'-thionucleoside analogue in a 7:1 ratio. DFT calculations suggest that this kinetic resolution originates from additional steric clash in the SN2-like transition state for 1',4'-trans isomers, causing a significant decrease in their reaction rate relative to 1',4'-cis counterparts. N-glycosylation of cyclic glycosyl donors with a purine nucleobase enabled the formation of novel 2-chloroadenine 4'-thionucleoside analogues. These proprietary molecules and other derivatives are currently being evaluated both in vitro and in vivo to establish their biological profiles.

Micro and mesoporous materials based on zeolite Y for the florol synthesis via the prins cyclization of isoprenol

Several parents and Sn-modified microporous and mesoporous catalysts were investigated in Prins cyclization of isoprenol with isovaleraldehyde for the production of the desired cis isomer of pyranol, Florol ® using dimethylcarbonate as a solvent in the temperature range of 30–60 °C. The highest selectivity to pyranols, 70% was obtained over microporous Sn-Y-80 (number denotes SiO2/Al2O3 ratio) at 40 °C, while 64% selectivity to pyranols was obtained at 99% conversion over dealuminated H-Y-80 exhibiting mesoporosity and low Brønsted to Lewis acid ratio of 0.16. For microporous catalysts even higher BA/LA ratio and large amounts of Lewis acid sites were beneficial, as was the case for H-Y-30 modified with SnCl2, because the reaction occurred mainly on the outer surface of the catalyst.

Influence of Lipid Conformations on the Interaction Energy between a Membrane and a Peripheral Protein

Peripheral membrane proteins are temporarily coupled to the surface of a membrane, penetrating into the lipid layer. In this work, it has been shown that the fraction of trans configurations of dihedral angles in hydrophobic chains of lipids decreases in the region of contact of peripheral membrane proteins with the membrane. This effect differs for different lipid chains and for dihedral angles at different distances from the beginning of a chain. A gosh configuration has a higher energy than a trans configuration. Consequently, the decrease in the fraction of trans configurations leads to an increase in the energy of the chain. The energy of chain conformations for the peripheral membrane protein considered in this work increases by ≈2 kJ/mol. A chain in chain conformations is involved in molecular mechanisms determining the elastic modulus of membranes. The energy stored in a conformation chain can be spent to the desorption of protein from the surface of the membrane and can be considered as a reason why the interaction of peripheral membrane proteins with the membrane is temporal.

Control of Photoisomerization Kinetics via Multistage Switching in Bimetallic Ru(II)-Terpyridine Complexes.

In this study, we carried out detailed experimental and theoretical investigation on photophysical, electrochemical, and photoisomerization behaviors of a new array of luminescent binuclear Ru(II) complexes derived from a phenylene-vinylene-substituted terpyridyl ligand possessing RT lifetimes within 60.3-410.5 ns. The complexes experienced trans-to-cis isomerization in MeCN on irradiation with visible light, accompanied by significant changes in their absorption and emission spectral profiles. The reverse cis-to-trans process is also possible with the use of ultraviolet (UV) light. On conversion from trans to cis isomers, the emission intensity increases substantially, while for the reverse process, luminescence quenching occurs. Thus, "off-on" and "on-off" emission switching is facilitated upon treatment with visible and UV light alternatively. By the use of chemical oxidants (ceric ammonium nitrate and potassium permanganate) and reductants (metallic sodium) as well as light of appropriate wavelengths, multistate switching phenomena involving reversible oxidation-reduction and trans-cis isomerization have been achieved. Interestingly, the rate of this multistate photoswitching process becomes much faster compared to only two-state trans-cis isomerization of these complexes. Density functional theory (DFT) and time-dependent-DFT (TD-DFT) calculations are also performed to obtain a clear picture of the electronic environment of the complexes and also for the appropriate assignment of absorption and emission spectral bands.

A computational and experimental study of cis-trans isomeric pesticides based on collision-induced dissociation of high-resolution mass spectrometry.

Pesticide isomers are widely available in agricultural production and may vary widely in biological activity, potency, and toxicity. Chromatographic and mass spectrometric analysis of pesticide isomers is challenging due to structural similarities. Based on liquid chromatography time-of-flight mass spectrometry, identification of cis-trans isomeric pesticides was achieved through retention time, characteristic fragment ions, and relative abundance ratio. Furthermore, theoretical and basic research has been conducted on the differences in characteristic fragment ions and their relative abundance ratios of cis-trans isomers. On the one hand, the cleavage pathways of six cis-trans isomers were elucidated through collision-induced dissociation to explain different fragment ions of the isomers. On the other hand, for those with the same fragment ions but different abundance ratios, energy-resolved mass spectrometry combined with computational chemical density functional theory in terms of kinetics, thermodynamics, and bond lengths was employed to explain the reasons for the differences in characteristic fragment ions and their abundance ratios. A high-resolution mass spectrometry method was developed for the separation and analysis of cis-trans isomers of pesticides in traditional Chinese medicine Radix Codonopsis, and six pesticide isomers were distinguished by retention time, product ions, and relative abundance ratios. The limits of quantification of the six pesticides were up to 10μg/kg, and the linear ranges of them were 10-200 μg/kg, with coefficients of determination (R2) > 0.99, which demonstrated the good linearity of the six pesticides. The recoveries of the pesticides at spiked concentrations of 10, 20, and 100 μg/kg reached 70-120% with relative standard deviations ≤20%. It was demonstrated that the application of the method was well suited for accurate qualitative and quantitative analysis for isomers with different structures, which could avoid false-negative results caused by ignoring other isomers effectively.

Designing Degradable Polymers from Tricycloalkenes via Complete Cascade Metathesis Polymerization.

Cascade metathesis polymerization has been developed as a promising method to synthesize complex but well-defined polymers from monomers containing multiple reactive functional groups. However, this approach has been limited to the monomers involving simple alkene/alkyne moieties or produced mainly non-degradable polymers. In this study, we demonstrate a complete cascade ring-opening/ring-closing metathesis polymerization (RORCMP) using various tricycloalkenes and two strategies for the efficient degradation. Through rational design of tricycloalkene monomers, the structure and reactivity relationship was explored. For example, tricycloalkenes with trans configuration in the central ring enabled faster and better selective cascade RORCMP than the corresponding cis isomers. Also, a 4-substituted cyclopentene moiety in the monomers significantly enhanced the overall cascade RORCMP performance, with the maximum turnover number (TON) reaching almost 10,000 and molecular weight up to 170 kg/mol using an amide-containing monomer. Furthermore, we achieved one-shot cascade multiple olefin metathesis polymerization using tricycloalkenes and a diacrylate, to produce new highly A,B-alternating copolymers with full degradability. Lastly, we successfully designed xylose-based tricycloalkenes to give well-defined polymers that underwent ultra-fast and complete degradation under mild conditions.

Designing Degradable Polymers from Tricycloalkenes via Complete Cascade Metathesis Polymerization

AbstractCascade metathesis polymerization has been developed as a promising method to synthesize complex but well‐defined polymers from monomers containing multiple reactive functional groups. However, this approach has been limited to the monomers involving simple alkene/alkyne moieties or produced mainly non‐degradable polymers. In this study, we demonstrate a complete cascade ring‐opening/ring‐closing metathesis polymerization (RORCMP) using various tricycloalkenes and two strategies for the efficient degradation. Through rational design of tricycloalkene monomers, the structure and reactivity relationship was explored. For example, tricycloalkenes with trans configuration in the central ring enabled faster and better selective cascade RORCMP than the corresponding cis isomers. Also, a 4‐substituted cyclopentene moiety in the monomers significantly enhanced the overall cascade RORCMP performance, with the maximum turnover number (TON) reaching almost 10,000 and molecular weight up to 170 kg/mol using an amide‐containing monomer. Furthermore, we achieved one‐shot cascade multiple olefin metathesis polymerization using tricycloalkenes and a diacrylate, to produce new highly A,B‐alternating copolymers with full degradability. Lastly, we successfully designed xylose‐based tricycloalkenes to give well‐defined polymers that underwent ultra‐fast and complete degradation under mild conditions.

Broadband Photodetection of Centimeter-Scale T-Phase Gallium Telluride Grown by Molecular Beam Epitaxy.

Two-dimensional (2D) semiconductors have recently attracted considerable attention due to their promising applications in future integrated electronic and optoelectronic devices. Large-scale synthesis of high-quality 2D semiconductors is an increasingly essential requirement for practical applications, such as sensing, imaging, and communications. In this work, homogeneous 2D GaTe films on a centimeter scale are epitaxially grown on fluorphlogopite mica substrates by molecular beam epitaxy (MBE). The epitaxial GaTe thin films showed an atomically 2D layered lattice structure with a T phase, which has not been discovered in the GaTe geometric isomer. Furthermore, semiconducting behavior and high mobility above room temperature were found in T-GaTe epitaxial films, which are essential for application in semiconducting devices. The T-GaTe-based photodetectors demonstrated respectable photodetection performance with a responsivity of 13 mA/W and a fast response speed. By introducing monolayer graphene as the substrate, we successfully realized high-quality GaTe/graphene heterostructures. The performance has been significantly improved, such as the responsivity was enhanced more than 20 times. These results highlight a feasible scheme for exploring the crystal phase of 2D GaTe and realizing the controlled growth of GaTe films on large substrates, which could promote the development of broadband, high-performance, and large-scale photodetection applications.

Crystallization-Induced Flower-like Superstructures via Peptoid Helix Assembly.

We report a unique method to construct hierarchical superstructures based on molecular programming of peptidomimetics. Chiral steric hindrance in the polymer backbone stabilizes peptoid helices that crystallize into nanosheets during solvent evaporation. The stacking of nanosheets results in flower-like superstructures. The helical peptoid, nucleated from chiral monomers, is characterized as locally stiffer and more extended than the unstructured peptoid. Molecular dynamics (MD) simulations further suggest a constraint on the dihedral angles and a preference toward the trans configuration, resulting in an extended chain structure. The nanosheet assemblies at various length scales indicate an extent of intermolecular ordering amplified by chiral steric hindrance. Such molecular programming and processing protocols will benefit the future design and controlled assembly of hierarchical peptidomimetics.

Synthesis of E-Isomer of α-Hydrazone Phosphonates via Nucleophilic Addition of Trialkyl Phosphite to Nitrile Imines (NIs) and DFT Calculations

Nitrile imines (NIs) belong to the nitrilium betaine family of 1,3-dipoles. Due to their high reactivity, NI compounds cannot be isolated and must be generated in situ before undergoing the desired transformation. NI derivatives were prepared by the utilization of N-phenyl hydrazine chloride precursors in the presence of a base. The title compounds α-hydrazone phosphonates have the potential to be biologically active and may serve as a precursor compound for other biologically active substances like amino phosphonic acids. Shortly, they are highly significant compounds in medicinal and synthetic chemistry. The derivatives of α-hydrazone phosphonate are synthesized by the nucleophilic addition of trialkyl phosphite to in situ generated NI derivatives and obtained in 44-95% isolated chemical yields. It is worth noting that only the E-isomer of the α-hydrazone phosphonates was obtained. Structural analyses of the α-hydrazone phosphonates were conducted by using proton and carbon NMR analysis along with FTIR. The researchers also performed DFT calculations including structural parameters (bond length, bond angle, and dihedral angle), HOMO and LUMO energy levels, and the zero-point vibrational energy (ZPE) for both E and Z geometric isomers of unsubstituted phenyl α-hydrazone phosphonate.

Molecular Twist-Induced Single-Crystal Isomerization and Valence Tautomeric Transitions in a Cobalt-Dioxolene Complex.

A mononuclear valence tautomeric (VT) complex, [Co(pycz)2(Sq)(Cat)] (1-trans), where pycz = 9-(pyridin-4-yl)-9H-carbazole, Sq⋅- = 3,5-di-tert-butyl-semiquinonato, and Cat2- = 3,5-di-tert-butyl-catecholato, is synthesized in the trans configuration, which undergoes one-step valence tautomeric transition above room temperature. Remarkably, 1-trans can transform into its isomeric structure, [Co(pycz)2(Sq)(Sq)] (1-cis), at temperature above 350 K in a single-crystal-to-single-crystal way by in situ molecular twist, and the resulting 1-cis exhibits a pronounced two-step VT transition during magnetic measurements that is rare for mononuclear VT complexes. Such drastic solid-state structural transformation is reported in VT compounds for the first time, which is actuated by a crystal surface's melting-recrystallization induced phase transition process. DFT calculations offer an underlying mechanism suggesting a concerted bond rotation during the structural transformation. The results demonstrate an unconventional approach that realizes structural transformation of VT complexes and the control of VT performance.