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1.
Luminescence ; 38(11): 1968-1976, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37653643

ABSTRACT

Broadly, the industrial applications of hydrazine cause environmental pollution and damage to living organisms because of the high toxicity of hydrazine. Therefore, monitoring hydrazine in the environmental system is of great significance to human health. Here, a new fluorescent probe PC-N2 H4 based on corrole dye was developed for the detection of hydrazine that had excellent specificity, low limit of detection (LOD: 88 nM), and a wide pH range (6-12). Upon addition of hydrazine into the probe solution, the strong red fluorescence was 'turned on' centred at 653 nm with a 127-fold fluorescence intensity enhancement. The detection mechanism was proved using ESI-MS, 1 H NMR, and density functional theoretical calculations. Importantly, the probe was utilized to fabricate a ready-to-use test strip to realize the visual inspection of hydrazine. Furthermore, PC-N2 H4 was successfully applied for practical detection of hydrazine in water samples with satisfactory recoveries ranging from 96.2% to 105.0%, and indicating that the designed PC-N2 H4 is highly promising for hydrazine detection in an aqueous environment. Considering the diverse toxicological functions of hydrazine, PC-N2 H4 was also successfully used to image exogenous hydrazine in HeLa cells and zebrafish.


Subject(s)
Hydrazines , Zebrafish , Animals , Humans , HeLa Cells , Spectrometry, Fluorescence , Hydrazines/chemistry , Fluorescent Dyes/chemistry , Water
2.
Inorg Chem ; 62(31): 12383-12391, 2023 Aug 07.
Article in English | MEDLINE | ID: mdl-37498974

ABSTRACT

Incredibly active electrocatalysts comprising earth-abundant materials that operate as effectively as noble metal catalysts are essential for the sustainable generation of hydrogen through water splitting. However, the vast majority of active catalysts are produced via complicated synthetic processes, making scale-up considerably tricky. In this work, a facile strategy is developed to synthesize superhydrophilic Ni/CeOx nanoparticles (NPs) integrated into porous carbon (Ni/CeOx@C) by a simple two-step synthesis strategy as efficient hydrogen evolution reaction (HER) electrocatalysts in 1.0 M KOH. Benefiting from the electron transport induced by the heterogeneous interface between Ni and CeOx NPs and the superhydrophilic structure of the catalyst, the resultant Ni2Ce1@C/500 catalysts exhibit a low overpotential of 26 and 184 mV at a current density of 10 and 300 mA cm-2, respectively, for HER with a small Tafel slope of 62.03 mV dec-1 and robust durability over 300 h, and its overpotential at a high current density is much better than the benchmark commercial Pt/C. Results revealed that the electronic rearrangement between Ni and CeOx integrated into porous carbon could effectively regulate the local conductivity and charge density. In addition, the oxygen vacancies and Ni/CeOx heterointerface promote water adsorption and hydrogen intermediate dissociation into H2 molecules, which ultimately accelerate the HER reaction kinetics. Notably, the electrochemical results demonstrate that structural optimization by regulating synthesis temperature and metal concentration could improve the surface features contributing to high electrical conductivity and increase the number of electrochemically active sites on the Ni/CeOx@C heterointerface, high crystal purity, and better electrical conductivity, resulting in its exceptional electrocatalytic performance toward the HER. These results indicated that the Ni/CeOx@C electrocatalyst has the potential for practical water-splitting applications because of its controlled production strategy and outstanding Pt-like HER performance.

3.
Spectrochim Acta A Mol Biomol Spectrosc ; 296: 122678, 2023 Aug 05.
Article in English | MEDLINE | ID: mdl-37019005

ABSTRACT

Here, a corrole-based dual-responsive fluorescent probe DPC-DNBS was rationally designed and synthesized for the separate detection of hydrazine (N2H4) and hydrogen sulfide (H2S) with high selectivity and sensitivity. The probe DPC-DNBS is intrinsically none fluorescent due to PET effect, however, addition of increasing amount of N2H4 or H2S to DPC-DNBS turned on an excellent NIR fluorescence centered at 652 nm and thereby provided a colorimetric signaling behavior. The sensing mechanism was verified by HRMS, 1H NMR and the DFT calculations. Common metal ions and anions do not interfere with the interactions of DPC-DNBS with N2H4 or H2S. Furthermore, the presence of N2H4 does not affect the detection of H2S; however, the presence of H2S interferes with the detection of N2H4. Hence, quantitative detection of N2H4 must occur in an H2S-free environment. The probe DPC-DNBS displayed some fascinating merits in separate detection of these two analytes, including large Stokes shift (233 nm), fast response (15 min for N2H4, 30 s for H2S), low detection limit (90 nM for N2H4, 38 nM for H2S), wide pH range (6-12) and outstanding biological compatibility. Significantly, DPC-DNBS was utilized to detect hydrazine in real water, soil and food samples. And its favorable performances for separate detection N2H4 and H2S were successfully demonstrated in HeLa cells and zebrafish, indicating its value of practical application in biology.


Subject(s)
Fluorescent Dyes , Hydrogen Sulfide , Humans , Animals , Fluorescent Dyes/chemistry , HeLa Cells , Zebrafish , Hydrazines , Spectrometry, Fluorescence
4.
J Colloid Interface Sci ; 627: 261-269, 2022 Dec.
Article in English | MEDLINE | ID: mdl-35849859

ABSTRACT

Photocatalytic hydrogen evolution is a promising and environmentally friendly strategy to prepare renewable energy sources thus addressing the energy crisis and environmental issues, and it is crucial to develop an ideal photocatalytic for highly efficient H2 production. Herein, the Co-doped CeO2 decorated on graphitic carbon nitride with N vacancies (NVs) heterostructure photocatalyst (Co-CeO2/DCN) is prepared via a simple self-assembly method. Due to the extended light absorption range, and efficient charge separation and migration derived from the introduction of NVs and the heterojunction structure, the photocatalytic activity of the Co-CeO2/DCN is largely promoted. The optimal sample 20-Co-CeO2/DCN shows a high H2 evolution rate of 1077.02 µmol g-1h-1 (λ > 400 nm), which is 113 and 33 times higher than the bare bulk graphitic carbon nitride (BCN) and CeO2, respectively. This work will provide a new strategy to develop high-performance photocatalysts using defect engineering and heterojunction engineering for H2 evolution.

5.
J Colloid Interface Sci ; 624: 433-442, 2022 Oct 15.
Article in English | MEDLINE | ID: mdl-35667205

ABSTRACT

Earth-abundant Fe-based oxides have drawn less attention in electrocatalytic water splitting owing to the inferior intrinsic activity and poor conductivity. Therefore, developing an effective method to increase the catalytic performance of Fe-based oxides is of great importance for the practical application. Herein, a novel Cr/N co-doped Fe3O4 electrocatalyst (denoted as Cr-Fe3O4-N/NF) is designed and prepared by a simple immersion treatment followed by a calcination method for efficient water splitting. The resultant Cr-Fe3O4-N/NF shows significant catalytic activity for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) with overpotentials of 218 and 95 mV at 10 mA cm-2. Furthermore, the water splitting system using Cr-Fe3O4-N/NF could afford a current density of 10 mA cm-2 at 1.53 V, which is superior to two-electrode system composed of Pt/C and RuO2. The high activities are attributed to the synergistic effect between Cr and N element doping. Specifically, the introduction of electron-deficient Cr is conductive to accelerate the dissociation process of water, adsorption process of intermediates, adjust the electronic structure. Simultaneously, N doping can increase the adsorption of H intermediates, provide more active sites for hydrogen absorption, and improve the electrical conductivity. This study provides a new strategy for Cr and N co-doped metal oxides electrocatalysts for high-performance water splitting.

6.
Anal Chim Acta ; 1195: 339460, 2022 Feb 22.
Article in English | MEDLINE | ID: mdl-35090651

ABSTRACT

Phthalates can penetrate the environment and enrich various aquatic organisms through the food chain, which is involved in promoting the growth of breast cancer. It is of current interest to develop new sensors for phthalates. We herein reported a hydrogen-bond competing fluorescent sensor, BANP, for the detection of dibutyl phthalate (DBP). The BANP compound was synthesized by assembling andrographolide (Andro), nitro- and cyano-substituted BODIPY dye (BCN), and polyethylene glycol derivatives (DSPE-mPEG5000). BANP was found to be a turn-on fluorescent probe for DBP in water with a detection limit of 0.13 µg/g; the DBP-water system acts as a hydrogen bond switch to turn on the fluorescence. And BANP fluorescently detected DBP in contaminated fish meat. Moreover, BANP sensed the DBP-induced growth of human breast cancer MCF-7 cells, and the release of Andro in the DBP-cultivated cancer cells inhibited the proliferation of the MCF-7 cells. Taken together, BANP is a DBP-responsive probe for sensitive DBP detection in water, cells, and fish meats. The BANP sensor may be used in both in vitro fluorescence and cellular imaging analyses. Our results show that guest-induced reassembly brings forth significant fluorescence change, which is a promising way of designing new fluorescent probes for the analysis of phthalates in the environment and food.


Subject(s)
Phthalic Acids , Animals , Dibutyl Phthalate , Diterpenes , Fluorescent Dyes , Humans
7.
Nanotechnology ; 33(9)2021 Dec 09.
Article in English | MEDLINE | ID: mdl-34808614

ABSTRACT

Herein, accessible and low-cost CoMn2O4@Ni3S2core-shell nanoneedle arrays have been prepared via a two-step approach comprised with hydrothermal-calcination and electrochemical deposition procedures, successfully. In the beginning, CoMn2O4nanoneedle arrays took root on Ni foam to form the core skeleton and subsequently, hierarchical Ni3S2nanosheets uniformly overlaid on the surface of CoMn2O4nanoneedles shaping the shell structure. This CoMn2O4@Ni3S2material was measured directly as supercapacitor electrode and presented high specific capacity of 192.2 mAh g-1with current density of 1 A g-1. Besides, the electrode delivered outstanding cyclical stability as the capacity retention attained 90.2% after charge-discharge measurement at a large current density of 10 A g-1for 10 000 cycles. Furthermore, a hybrid supercapacitor assembled by CoMn2O4@Ni3S2cathode and activated carbon anode represented a high energy density of 51.2 Wh kg-1with the power density of 1030.0 W kg-1. This work shows a facile and inexpensive procedure to design high-performance and strong-stability supercapacitor electrodes.

8.
Nanotechnology ; 33(7)2021 Nov 24.
Article in English | MEDLINE | ID: mdl-34555817

ABSTRACT

It is still a huge challenge to develop highly efficient and low-cost non-precious metal-based electrocatalysts for overall water splitting in alkaline electrolytes. Herein, Cr and Fe co-doped CoP porous mesh nanosheets (Mesh-CrFe-CoP NSs) were synthesized through hydrolysis reaction, ion exchange etching and subsequent low-temperature phosphating process. The Mesh-CrFe-CoP NSs provides overpotentials at a current density of 10 mA cm-2under alkaline electrolyte of 103.7 mV and 256.4 mV for HER and OER, respectively. Furthermore, when using Mesh-CrFe-CoP NSs as anode and cathode, the water splitting system could afford a current density of 10 mA cm-2at 1.55 V, which is better than an electrolytic cell composed of 20% Pt/C and RuO2. The excellent electrocatalytic performance of Mesh-CrFe-CoP NSs is attributed to the co-doping and porous nanostructure. Specifically, the Cr and Fe co-doped porous CoP nanosheets electrocatalyst not only provided abundant exposure active sites, accelerated the entry of liquid and the diffusion of gas, but also regulated the electronic environment of active sites, and thus enhanced the electrochemical performance. This work proposes a strategy for the rational design of highly efficient and stable non-precious metal co-doped phosphide electrocatalysts in the of electrochemical water splitting.

9.
Dalton Trans ; 50(7): 2414-2425, 2021 Feb 21.
Article in English | MEDLINE | ID: mdl-33522540

ABSTRACT

Designing a Pt-alternative cocatalyst capable of dissociating HO-H bonds is of great significance yet challenging for the development of high-efficiency and cost-effective water splitting photocatalytic systems. In this study, we designed and constructed a 0D ultrafine ruthenium (U-Ru) quantum dot decorated 3D porous g-C3N4 (3DpCN) nanohybrid (U-Ru/3DpCN) for photocatalytic hydrogen evolution, in which the U-Ru quantum dots act as cocatalysts accelerating the surface proton reduction reaction, and the 3D porous architecture assembled by 2D ultrathin nanosheets inherits a short charge diffusion distance and has a large specific surface area. Owing to these structural and physicochemical merits, the optimal photocatalyst U-1Ru/3DpCN achieves a superior hydrogen evolution performance of 2945.47 µmol g-1 h-1 under visible light with a high apparent quantum efficiency (AQE) of 9.5% at 420 nm, which is close to Pt-cocatalyst/3DpCN and better than most reported co-catalysts/g-C3N4 photocatalytic systems. Experimental results indicate that the formed Schottky junction between U-Ru and 3DpCN contributes to efficient charge separation, and DFT calculations show that the Ru-cocatalyst/g-C3N4 system has an appropriate hydrogen adsorption Gibbs free energy (ΔGH*) of 0.24 eV, which are both responsible to improve the photocatalytic performance. This study provides a new way to develop excellent photocatalysts for hydrogen evolution by the integration of cost-effective Ru quantum dot cocatalysts with nanostructured semiconductors.

10.
J Colloid Interface Sci ; 585: 108-117, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33279692

ABSTRACT

Developing high-efficient and low-cost photocatalysts is of great significance yet challenging for photocatalytic hydrogen evolution. Herein, we report a 2D/2D Ru-modulated CoP nanosheets (Ru-CoP-x, where x refers the Ru-to-Co molar ratio)/g-C3N4 nanosheets (GCN NSs) ternary hybrid as a photocatalyst for hydrogen evolution under visible light. The optimal photocatalyst 25% Ru-CoP-1:8/GCN NSs exhibits an excellent hydrogen evolution rate of 1172.5 µmol g-1 h-1 under visible light with a high apparent quantum efficiency (AQE) of 3.49% at 420 nm, which is close to Pt/g-C3N4 photocatalytic system and higher than most reported transition metal phosphides (TMP)/g-C3N4 photocatalytic system. Experimental results indicate that the higher photocatalytic hydrogen evolution performance can be mainly attributed to the binary Ru-CoP-x co-catalyst with efficient charge separation and promoted surface water reduction kinetics, and the 2D/2D self-assembly structure with strong interface Schottky effect and short charge transport distance. This study provides a new approach to develop cost-effective Pt-alternative co-catalysts for photocatalytic hydrogen evolution by incorporating a small amount of ruthenium into the transition metal phosphides.

11.
Nanotechnology ; 31(29): 295403, 2020 May 01.
Article in English | MEDLINE | ID: mdl-32197261

ABSTRACT

In this study, a three-dimensional (3D) hierarchical Co3O4@NiS core-shell heterostructure supported on nickel foam (NF) has been constructed. This Co3O4@NiS/NF can directly serve as a binder-free electrode for a pseudocapacitor, which could achieve a high specific capacitance of 1395.3 F g-1 at a current density of 1 A g-1 in 6 M KOH electrolyte, and an ideal rate capability of 711 F g-1 at a current density of 10 A g-1. Additionally, the electrode has a high capacitance retention of 89.9% after 5000 cycles. The asymmetric supercapacitor exhibits the maximum energy density of 61.34 W h kg-1 at a power density of 800 W kg-1, as well as an excellent cycling life of 89.3% capacitance retention. The enhanced electrochemical performance can be mainly ascribed to the special 3D core-shell nanowire arrays nanostructure with great conductivity, enlarged surface area, abundant accessible active sites and intrinsic stability. We anticipate that the present Co3O4@NiS/NF could be a promising electrode material for energy storage applications.

12.
J Colloid Interface Sci ; 506: 93-101, 2017 Nov 15.
Article in English | MEDLINE | ID: mdl-28728034

ABSTRACT

The artificially Z-scheme heterojunctions between WO3 nanosheet and SnNb2O6 nanosheet with strongly coupled heterointerfaces were successfully constructed via a simple hydrothermal coassembly method. Transmission electron microscopy (TEM) and high-resolution TEM proved that an intimate contact interface was formed. The synthesized heterojunctions exhibites enhanced photodegradation efficiency for Rhodamine B under irradiation of visible light, and the highest reaction rate over 30%-WO3/SnNb2O6 nanosheet heterojunctions is about 4.7-fold and 2-fold higher than that of pristine WO3 and SnNb2O6, respectively. Such a considerable improvement could be mainly attributed to the rapid migration of the photo-induced e-/h+ pairs through the nanosheets-coupled heterojunction interfaces. A possible directly Z-scheme charge transfer mechanism was proposed for the elimination of organic contaminants under irradiation of visible light. This work may furnish new insights into development of novel 2D/2D nanosheet heterojunctions with the enhanced photocatalytic activity.

13.
Chem Commun (Camb) ; 52(19): 3797-800, 2016 Mar 07.
Article in English | MEDLINE | ID: mdl-26864604

ABSTRACT

An ammonium-crown ether host-guest supramolecular cation-templated synthetic methodology has been developed to construct a structurally unprecedented heterobicluster-metal coordination polymer (HCM-CP 1) based on tetranuclear clusters [WS4Cu3](+) with different connection environments, pentanuclear clusters [WS4Cu4](2+), and Cu(+) building metal ions. HCM-CP 1 exhibits enhanced NLO properties, which may be ascribed to the incorporation of diverse building cluster components.

14.
ACS Appl Mater Interfaces ; 7(34): 19234-42, 2015 Sep 02.
Article in English | MEDLINE | ID: mdl-26285085

ABSTRACT

Design and exploitation of efficient visible light photocatalytic systems for water splitting and degradation of organic dyes are of huge interest in the fields of energy conversion and environmental protection. Herein, two-dimensional CaIn2S4/g-C3N4 heterojunction nanocomposites with intimate interfacial contact have been synthesized by a facile two-step method. Compared with pristine g-C3N4 and CaIn2S4, the CaIn2S4/g-C3N4 heterojunction nanocomposites exhibited significantly enhanced H2 evolution and photocatalytic degradation of methyl orange (MO) activities under visible light irradiation. The optimal CaIn2S4/g-C3N4 nanocomposite shows a H2 evolution rate of 102 µmol g(-1) h(-1), which is more than 3 times that of pristine CaIn2S4. The mechanisms for improving the photocatalytic performance of the CaIn2S4/g-C3N4 nanocomposites were proposed by using the photoluminescence measurement and electrochemical analyses. It was demonstrated that the enhanced photocatalytic performance of CaIn2S4/g-C3N4 heterojunction nanocomposites mainly stems from the enhanced charge separation efficiency. In addition, a plausible mechanism for the degradation of MO dye over CaIn2S4/g-C3N4 nanocomposites is also elucidated using active species scavenger's studies.

15.
Chemistry ; 21(21): 7914-26, 2015 May 18.
Article in English | MEDLINE | ID: mdl-25877804

ABSTRACT

Three unusual three-dimensional (3D) tetrazine chromophore-based metal-organic frameworks (MOFs) {(Et4 N)[WS4 Cu3 (CN)2 (4,4'-pytz)0.5 ]}n (1), {[MoS4 Cu4 (CN)2 (4,4'-pytz)2 ]⋅CH2 Cl2 }n (2), and {[WS4 Cu3 (4,4'-pytz)3 ]⋅[N(CN)2 ]}n (3; 4,4'-pytz=3,6-bis(4-pyridyl)tetrazine) have been synthesized and characterized by using FTIR and UV/Vis spectroscopy, elemental analysis, powder X-ray diffraction, gel permeation chromatography, steady-state fluorescence, and thermogravimetric analysis; their identities were confirmed by single-crystal X-ray diffraction studies. MOF 1 possesses the first five-connected M/S/Cu (M=Mo, W) framework with an unusual 3D (4(4) ⋅6(6) ) topology constructed from T-shaped [WS4 Cu3 ](+) clusters as nodes and single CN(-) /4,4'-pytz bridges as linkers. MOF 2 features a novel 3D MOF structure with (4(20) ⋅6(8) ) topology, in which the bridging 4,4'-pytz ligands exhibit unique distorted arch structures. MOF 3 displays the first 3D MOF structure based on flywheel-shaped [WS4 Cu3 ](+) clusters with a non-interpenetrating honeycomb-like framework and a heavily distorted "ACS" topology. Steady-state fluorescence studies of 1-3 reveal significant fluorescence emissions. The nonlinear optical (NLO) properties of 1-3 were investigated by using a Z-scan technique with 5 ns pulses at λ=532 nm. The Z-scan experimental results show that the π-delocalizable tetrazine-based 4,4'-pytz ligands contribute to the strong third-order NLO properties exhibited by 1-3. Time-dependent density functional theory studies afforded insight into the electronic transitions and spectral characterization of these functionalized NLO molecular materials.

16.
Anal Chim Acta ; 812: 145-51, 2014 Feb 17.
Article in English | MEDLINE | ID: mdl-24491775

ABSTRACT

A simple and versatile ratiometric fluorescent Fe(3+) detecting system, probe 1, was rationally developed based on the Fe(3+)-mediated deprotection of acetal reaction. Notably, this reaction was firstly employed to design fluorescent Fe(3+) probe. Upon treatment with Fe(3+), probe 1 showed ratiometric response, with the fluorescence spectra displaying significant red shift (up to 132 nm) and the emission ratio value (I522/I390) exhibiting approximately 2362-fold enhancement. In addition, the probe is highly sensitive (with the detection limit of 0.12 µM) and highly selective to Fe(3+) over other biologically relevant metal ions. The sensing reaction product of the probe with Fe(3+) was confirmed by NMR spectra and mass spectrometry. TD-DFT calculation has demonstrated that the ratiometric response of probe 1 to Fe(3+) is due to the regulation of intramolecular charge transfer (ICT) efficiency. Moreover, the practical utility in fluorescence detection of Fe(3+) in human blood serum was also conducted, and probe 1 represents the first ratiometric fluorescent probe that can be used to monitor Fe(3+) level in human blood serum. Finally, probe 1 was further employed in living cell imaging with pancreatic cancer cells, in which it displayed low cytotoxicity, satisfactory cell permeability, and selective ratiometric response to Fe(3+).


Subject(s)
Ferric Compounds/blood , Fluorescent Dyes/chemistry , Humans , Limit of Detection
17.
Org Biomol Chem ; 11(47): 8214-20, 2013 Dec 21.
Article in English | MEDLINE | ID: mdl-24166284

ABSTRACT

In this work, compound 1 has been rationally designed and synthesized as a new fluorescent probe for biological thiols. Notably, probe 1 has almost no background fluorescence (Φf < 0.0001) in aqueous solutions; however, it exhibited fluorescence turn-on response to thiols with high sensitivity (a 246-fold fluorescence enhancement and a low detection limit of 0.22 µM for Cys). Moreover, probe 1 showed excellent thiol specificity over other biologically relevant species. The kinetic studies indicated that the probe responded to thiols rapidly, and the pseudo-first-order rate constants of probe 1 reaction with Cys, Hcy, and GSH were determined to be 1.85842, 0.67656, and 0.51519 min(-1), respectively. A possible detection mechanism was proposed to involve the Michael addition of the thiol to the α,ß-unsaturated ketone, followed by a cleavage of the hemiketal group, thereby leading to the formation of a fluorescent 7-hydroxyl coumarin derivative. Furthermore, the optical responses of probe 1 to thiols were studied by TD-DFT calculations. Finally, probe 1 has been successfully applied to the detection of biological thiols in human blood serum. And the intracellular imaging applications established that probe 1 can be used to detect different concentrations of intracellular thiols in living cells.


Subject(s)
Coumarins/chemistry , Fluorescent Dyes/chemistry , Pancreatic Neoplasms/chemistry , Sulfhydryl Compounds/blood , Cell Survival , Fluorescent Dyes/chemical synthesis , Humans , Hydrogen-Ion Concentration , Kinetics , Models, Molecular , Molecular Structure , Pancreatic Neoplasms/pathology , Quantum Theory
18.
Org Biomol Chem ; 11(25): 4250-7, 2013 Jul 07.
Article in English | MEDLINE | ID: mdl-23680927

ABSTRACT

A novel porphyrin derivative bearing one D-π-A-π-D pyrimidine chromophore at the periphery was designed, prepared, and studied using the Z-scan technique, the results showing that this compound exhibits enhanced nonlinear optical (NLO) absorption, refraction and optical limiting responses. The significant NLO properties can be ascribed to an effective combination of distinct nonlinear mechanisms.


Subject(s)
Coloring Agents/chemistry , Porphyrins/chemistry , Pyrimidines/chemistry , Fluorescence , Models, Molecular , Spectrophotometry, Ultraviolet
19.
J Org Chem ; 77(18): 8124-30, 2012 Sep 21.
Article in English | MEDLINE | ID: mdl-22924388

ABSTRACT

Several Pd and/or Au bis-metalated [32]octaphyrins(1,0,1,0,1,0,1,0) were theoretically designed with rich conformations of Hückel or Möbius topology. The conformations and hence properties of macrocycles were tuned by twisting the active pyrrolic ring either clockwise (through multistep reactions with several Hückel and Möbius macrocyclic intermediates) or anticlockwise (via a direct Hückel-Hückel chiral interconversion). The encapsulated metal atoms, M(1), M(2) = Pd, Au, give different impacts on these two reaction processes. Facile occurrences of chiral interconversions between two enantiomers of bis-metalated octaphyrins were predicted with the largest activation barrier less than 40 kcal/mol. Some Au-coordinated octaphyrins (M(1) = Au) were demonstrated to be thermodynamically stable with large negative nucleus-independent chemical shift (NICS) values, which are comparable to those of the synthetic Pd-coordinated complexes. The free-base [32]octaphyrins(1,0,1,0,1,0,1,0) display the characteristic absorption spectra with distinct sharp Soret-like bands. After metalation, the Soret-like bands are red-shifted in different degrees along with the appearance of rather weak Q-like band. The heterometal-coordinated complexes (i.e., M(1) ≠ M(2)) show stronger and more splitting absorptions than the homometal-coordinated ones with M(1) = M(2). The hyperpolarizabilities sharply augment with the metalation in Hückel systems due to the destruction of the centrosymmetry and the increase in polarizability by coordinated metal atoms.

20.
J Phys Chem A ; 116(3): 913-23, 2012 Jan 26.
Article in English | MEDLINE | ID: mdl-22165975

ABSTRACT

The photocyclization behavior and dynamic conformational transition of photochromic switches of diarythene derivatives in solutions are investigated by using the density functional theory (DFT) and molecular dynamics (MD) simulations. Three possible conformations, antiparallel (anti), parallel (para), and twist, for the open-ring isomers of 1,2-bis(2-methylbenzothiophene-3-yl)maleic anhydride are located. Both PCM-B3LYP/6-31G* calculations and MD simulations demonstrate that anti and twist open-ring isomers can interconvert freely in n-hexane and acetonitrile solutions at room temperature. The statistical ratio of twist to anti isomers from MD simulations is 2.09 in n-hexane and 1.07 in CH(3)CN, in qualitative agreement with those (1.18 in n-hexane and 1.05 in CH(3)CN) estimated from Arrhenius analysis of DFT activation energies. The solvent polarity has little influence on the isomerization of open-ring isomers in the ground state. Due to the evident charge transfer upon excitations, the solvent effects on the electronic structures and absorption spectra of low-lying excited states (S(1) and S(2)) are more significant. For such charge-transfer excited states, the long-range corrected functional CAM-B3LYP gives better agreement with the experimental spectra than B3LYP. The solvent polarity and polarization of the charge-transfer excited states are crucial for fabricating the novel functionalized photochromic molecular switches.


Subject(s)
Ethylenes/chemistry , Molecular Conformation , Molecular Dynamics Simulation , Photochemical Processes , Quantum Theory , Solutions , Solvents/chemistry , Spectrophotometry, Ultraviolet , Stereoisomerism
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