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1.
Langmuir ; 2024 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-38332611

RESUMO

An asymmetric structure is an important strategy for designing highly conductive molecular wires for a gap-fixed molecular circuit. As the conductance enhancement in the current strategy is still limited to about 2 times, we inserted a methylene group as a spacer in a conjugated structure to modulate the structural symmetry. We found that the conductance drastically enhanced in the asymmetric molecular wire to 1.5 orders of magnitude as high as that in the symmetric molecular wire. First-principles quantum transport studies attributed the effective enhancement to the synchronization of improved energy alignment and nearly symmetric coupling between the frontier orbitals and the electrodes.

2.
Nano Lett ; 23(20): 9399-9405, 2023 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-37877237

RESUMO

An accurate rule for predicting conductance is the cornerstone of developing molecular circuits and provides a promising solution for miniaturizing electric circuits. The successful prediction of series molecular circuits has proven the possibility of establishing a rule for molecular circuits under quantum mechanics. However, the quantitatively accurate prediction has not been validated by experiments for parallel molecular circuits. Here we used 1,3-dihydrobenzothiophene (DBT) to build the parallel molecular circuits. The theoretical simulation and single-molecule conductance measurements demonstrated that the conductance of the molecule containing one DBT is the unprecedented linear combination of the conductance of the two individual channels with respective contribution weights of 0.37 and 0.63. With these weights, the conductance of the molecule containing two DBTs is predicted as 1.81 nS, matching perfectly with the measured conductance (1.82 nS). This feature offers a potential rule for quantitatively predicting the conductance of parallel molecular circuits.

3.
Molecules ; 29(11)2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38893316

RESUMO

For designing single-molecule devices that have both conjugation systems and structural flexibility, a hyperconjugated molecule with a σ-π bond interaction is considered an ideal candidate. In the investigation of conductance at the single-molecule level, since few hyperconjugation systems have been involved, the strategy of building hyperconjugation systems and the mechanism of electron transport within this system remain unexplored. Based on the skipped-conjugated structure, we present a rational approach to construct a hyperconjugation molecule using a hydroxyl group, which serves as a bridge to interact with the conjugated fragments. The measurement of single-molecule conductance reveals a two-fold conductance enhancement of the hyperconjugation system having the 'bridging' hydroxyl group compared to hydroxyl-free derivatives. Theoretical studies demonstrate that the hydroxyl group in the hyperconjugation system connects the LUMO of the two conjugated fragments and opens a through-space channel for electron transport to enhance the conductance.

4.
Angew Chem Int Ed Engl ; : e202410710, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38949854

RESUMO

Metallo-supramolecular cages have garnered tremendous attention for their diverse yet molecular-level precision structures. However, physical properties of these supramolecular ensembles, which are of potential significance in molecular electronics, remain largely unexplored. We herein constructed a series of octahedral metallo-cages and cage-fullerene complexes with notably enhanced structural stability. As such, we could systematically evaluate the electrical conductivity of these ensembles at both single-molecule level and aggregated bulk state (as well-defined films). Our findings reveal that counteranions and fullerene guests play a pivotal role in determining the electrical conductivity of aggregated state, while such effects are less significant for single-molecule conductance. Both counteranions and fullerenes effectively tune the electronic structures and packing density of metallo-supramolecular assemblies, and facilitate efficient charge transfer between the cage hosts and fullerenes, resulting in a notable one order of magnitude increase in electrical conductivity of the aggregated state.

5.
BMC Med ; 21(1): 270, 2023 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-37488510

RESUMO

BACKGROUND: The introduction of multiparameter MRI and novel biomarkers has greatly improved the prediction of clinically significant prostate cancer (csPCa). However, decision-making regarding prostate biopsy and prebiopsy examinations is still difficult. We aimed to establish a quick and economic tool to improve the detection of csPCa based on routinely performed clinical examinations through an automated machine learning platform (AutoML). METHODS: This study included a multicenter retrospective cohort and two prospective cohorts with 4747 cases from 9 hospitals across China. The multimodal data, including demographics, clinical characteristics, laboratory tests, and ultrasound reports, of consecutive participants were retrieved using extract-transform-load tools. AutoML was applied to explore potential data processing patterns and the most suitable algorithm to build the Prostate Cancer Artificial Intelligence Diagnostic System (PCAIDS). The diagnostic performance was determined by the receiver operating characteristic curve (ROC) for discriminating csPCa from insignificant prostate cancer (PCa) and benign disease. The clinical utility was evaluated by decision curve analysis (DCA) and waterfall plots. RESULTS: The random forest algorithm was applied in the feature selection, and the AutoML algorithm was applied for model establishment. The area under the curve (AUC) value in identifying csPCa was 0.853 in the training cohort, 0.820 in the validation cohort, 0.807 in the Changhai prospective cohort, and 0.850 in the Zhongda prospective cohort. DCA showed that the PCAIDS was superior to PSA or fPSA/tPSA for diagnosing csPCa with a higher net benefit for all threshold probabilities in all cohorts. Setting a fixed sensitivity of 95%, a total of 32.2%, 17.6%, and 26.3% of unnecessary biopsies could be avoided with less than 5% of csPCa missed in the validation cohort, Changhai and Zhongda prospective cohorts, respectively. CONCLUSIONS: The PCAIDS was an effective tool to inform decision-making regarding the need for prostate biopsy and prebiopsy examinations such as mpMRI. Further prospective and international studies are warranted to validate the findings of this study. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2100048428. Registered on 06 July 2021.


Assuntos
Inteligência Artificial , Neoplasias da Próstata , Masculino , Humanos , Estudos Retrospectivos , Algoritmos , Aprendizado de Máquina
6.
Small ; 18(20): e2200361, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35481610

RESUMO

Investigating the correlations of electron transport between multiple channels shows vital promises for the design of molecule-scale circuits with logic operations. To control the electron transport through multiple channels, the modulation of electronegativity shows an effective frontier orbit control method with high universality to explore the interactions between transport channels. Here, two series of compounds with a single nitrogenous conductive channel (Sg) and dual-channels (Db) are designed to explore the influence of electronegativity on electron tunneling transport. Single-molecule conductance measured via the scanning tunneling microscope break junction technique (STM-BJ) reveals that the conductance of Db series is significantly suppressed as the electronegativity of nitrogen becomes negative, while the suppression on Sg is less obvious. Theoretical calculations confirm that the effect of electronegativity extends to a dispersive range of molecular frameworks owing to the delocalized orbital distribution from the dual-channel structure, resulting in a more significant conductance suppression effect than that on the single-channel. This study provides the experimental and theoretical potentials of electronegativity gating for molecular circuits.


Assuntos
Nanotecnologia , Nitrogênio , Condutividade Elétrica , Transporte de Elétrons
7.
Nano Lett ; 21(22): 9729-9735, 2021 11 24.
Artigo em Inglês | MEDLINE | ID: mdl-34761680

RESUMO

Unveiling the internal dynamics of rotation in molecular machine at single-molecule scale is still a challenge. In this work, three crank-shaped molecules are elaborately designed with the conformational flipping between syn and anti fulfilled by two naphthyl groups rotating freely along 1,3-butadiynyl axis. By investigating the single-molecule conductance using scanning tunnelling microscope break junction (STM-BJ) technique and theoretical simulation, the internal rotation of these crank-shaped molecules is well identified through low and high conductance corresponding to syn- and anti-conformations. As demonstrated by theoretically computational study, the orbital energy changes with the conformational flipping and influences the intraorbital quantum interference, thus eventually modulating the single-molecule conductance. This work demonstrates single-molecule conductance measurement to be a rational approach for characterizing the internal rotation of molecular machines.


Assuntos
Conformação Molecular , Nanotecnologia , Rotação , Simulação por Computador
8.
Angew Chem Int Ed Engl ; 61(40): e202210097, 2022 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-35981229

RESUMO

The Fano resonance in single-molecule junctions could be created by interaction with discrete and continuous molecular orbitals and enables effective electron transport modulation between constructive and destructive interference within a small energy range. However, direct observation of Fano resonance remains unexplored because of the disappearance of discrete orbitals by molecule-electrode coupling. We demonstrated the room-temperature observation of Fano resonance from electrochemical gated single-molecule conductance and current-voltage measurements of a para-carbazole anion junction. Theoretical calculations reveal that the negative charge on the nitrogen atom induces a localized HOMO on the molecular center, creating Fano resonance by interfering with the delocalized LUMO on the molecular backbone. Our findings demonstrate that the Fano resonance in electron transport through single-molecule junctions opens pathways for designs of interference-based electronic devices.

9.
Cancer Cell Int ; 20: 87, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32206038

RESUMO

BACKGROUND: LncRNA NEAT1 has been identified as a tumour driver in many human cancers. However, the underlying mechanism of lncRNA NEAT1 in diffuse large B-cell lymphoma (DLBCL) progression is unclear. METHODS: The expression levels of NEAT1, GLI1 and miR-34b-5p were detected by RT-qPCR and Western blotting in DLBCL tissues and cell lines. MTT and colony formation assays were performed to examine cell proliferation, while annexin-V staining and TUNEL assays were performed to measure cell apoptosis. The effect of NEAT1, GLI1 and miR-34b-5p on cell cycle-associated proteins was evaluated by Western blotting. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were employed to investigate the interaction between NEAT1 and miR-34b-5p or GLI1 and miR-34b-5p. Moreover, chromatin immunoprecipitation (ChIP) was performed to demonstrate the interaction between MYC and NEAT1. RESULTS: NEAT1 and GLI1 were upregulated while miR-34b-5p was downregulated in DLBCL tissues and cell lines compared to normal controls. Knockdown of NEAT1 or overexpression of miR-34b-5p inhibited cell proliferation but promoted cell apoptosis. Overexpression of NEAT1 reversed GLI1-knockdown induced attenuation of cell proliferation. In other words, NEAT1 acted as a competing endogenous RNA (ceRNA), regulating the miR-34b-5p-GLI1 axis, further affecting the proliferation of DLBCL. Moreover, MYC modulated NEAT1 transcription by directly binding to the NEAT1 promoter. CONCLUSION: We revealed that MYC-regulated NEAT1 promoted DLBCL proliferation via the miR-34b-5p-GLI1 pathway, which could provide a novel therapeutic target for DLBCL.

10.
Inorg Chem ; 58(22): 15008-15012, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31689092

RESUMO

A series of lanthanide-titanium oxo clusters (LnTOCs), Ln2Ti8-Ac, Ln2Ti8-p-Toluic, and Ln2Ti8-Anthra (Ln = Eu and Tb), were prepared based on acetic acid (HAc), p-toluic acid (Hp-Toluic), and anthracene-9-carboxylic acid (HAnthra). Crystal structural analysis showed that these clusters possess the same metal topology framework, in which eight Ti4+ ions form a cube and two Ln3+ ions are located on the opposite faces of the cube. The luminescence investigation discovered that the Eu2Ti8-Ac displays the highest quantum yields with 15.6%, and the conjugation effect of ligand substituents can lower the triplet state energy of ligands, thus regulating the luminescence quantum yield of the Ln2Ti8 clusters. These results suggest that the triplet excited-state energy of the ligands should match well with the energy levels of Ln3+ to enhance the luminescence.

11.
Mikrochim Acta ; 186(8): 560, 2019 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-31338683

RESUMO

A simple and fast method is described for the extraction of polycyclic aromatic hydrocarbons (PAHs) from complex samples. It is based on the use of a nanoferrofluid modified with a ternary hydrophobic deep eutectic solvent. A predictive model was used for the selection of the optimal eutectic mixture. The entire microextraction only takes a few minutes for completion. Under the optimal extraction conditions (by using menthol, borneol and camphor in a molar ratio of 5:1:4; 80 mg of nanoferrofluid), it offers marked improvements in terms of selectivity and sensitivity. The limits of detection range between 0.31 and 5.9 ng·L-1, and recoveries from spiked samples between 91.3 and 121%. In addition, the strong interactions between PAHs and the extractant were supported by quantum mechanical calculations. This results in a better insight into the microextraction mechanism, providing a fast, environmentally friendly and effective route for the optimization of pretreatment parameters. The method was successfully applied to the determination of the PAHs naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[b]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene and indeno[1,2,3-c,d]pyrene in 12 kinds of coffee samples after different roasting conditions. Graphical abstract Schematic presentation of nanoferrofluid modified with ternary hydrophobic deep eutectic solvent and their application for selective microextraction of ultra-trace polycyclic aromatic hydrocarbons in coffee prior to HPLC analysis.

12.
Org Biomol Chem ; 16(40): 7438-7445, 2018 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-30264839

RESUMO

A tert-butyl carbazole-modified difluoroboron ß-diketonate complex (TCbzB) has been synthesized. Although no traditional gelation group was involved in TCbzB, it could form organogels in the mixed solvents of o-dichlorobenzene/cyclohexane (v/v = 1/5 or 1/2), toluene/cyclohexane (v/v = 1/2) and chlorobenzene/cyclohexane (v/v = 1/2). Interestingly, an orange organogel was obtained in o-dichlorobenzene/cyclohexane (v/v = 1/2) with relatively high polarity and red organogels were gained in the other three mixed solvents with relatively low polarity. TCbzB self-assembled into H-aggregates and J-aggregates in orange and red organogels, respectively, and the corresponding xerogels emitted yellow and red light, respectively, under UV illumination. The red emission of the xerogel-based film could be quenched significantly by gaseous n-propylamine and aniline because of the decomplexation of the difluoroboron ß-diketonate complex by n-propylamine and the weak interactions between aniline and boron difluoride units.

13.
Inorg Chem ; 56(21): 13257-13266, 2017 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-28985081

RESUMO

An asymmetric bis(dithienylethene-acetylide) ruthenium(II) complex trans-Ru(dppe)2(L1o)(L2o) (1oo) incorporating two different dithienylethene-acetylides (L1o and L2o) was designed to modulate multistate photochromism in view of the well separated ring-closing absorption bands between L1o and L2o. Upon irradiation with appropriate wavelengths of light, complex 1 undergoes stepwise photocyclization and selective photocycloreversion to afford four states (1oo, 1co, 1oc, and 1cc). As a contrast, symmetric complexes trans-Ru(dppe)2(L1o)2 (2oo) and trans-Ru(dppe)2(L2o)2 (3oo) with two identical dithienylethene-acetylides were synthesized, and the corresponding photochromic behavior was investigated. The photochromic properties of the oxidized species (1oo+/1co+/1oc+/1cc+, 2oo+/2co+/2cc+, and 3oo+/3co+/3cc+) were also investigated. The ring-closing absorption bands of one-electron oxidized species 1oo+, 2oo+, and 3oo+ show obvious blue shifts relative to those of 1oo, 2oo, and 3oo, respectively. The ring-closing absorption bands in both neutral and oxidized species grow progressively following oo → oc/co → cc and oo+ → oc+/co+ → cc+. As revealed by spectroscopic, electrochemical, and computational studies, complex 1 displays eight switchable states through stepwise photocyclization, selective cycloreversion, and a reversible redox process.

14.
Inorg Chem ; 56(16): 9461-9473, 2017 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-28441021

RESUMO

1,2-Bis[[(diphenylphosphino)methyl](phenyl)phosphino]ethane (dpmppe) was prepared as a new tetraphosphine, and the corresponding rac and meso stereoisomers were successfully separated in view of their solubility difference in acetone. The substitution of PPh3 into Pt(PPh3)2(C≡CR)2 (R = aryl) with rac- or meso-dpmppe gives Pt(rac-dpmppe)(C≡CR)2 or Pt(meso-dpmppe)(C≡CR)2, respectively. Using Pt(rac-dpmppe)(C≡CR)2 or Pt(meso-dpmppe)(C≡CR)2 as a precursor, PtAg2 heterotrinuclear cluster complexes were synthesized and characterized by X-ray crystallography. Depending on the conformations of tetraphosphine, the structures of PtAg2 complexes supported with rac- and meso-dpmppe are quite different. The higher molecular rigidity of rac-dpmppe-supported PtAg2 complexes results in stronger phosphorescent emission than that of PtAg2 species with meso-dpmppe. The high phosphorescent quantum yields (as high as 90.5%) in doping films warrant these PtAg2 complexes as excellent phosphorescent dopants in organic light-emitting diodes (OLEDs). The peak current and external quantum efficiencies in solution-processed OLEDs are 61.0 cd A-1 and 18.1%, respectively. Electroluminescence was elaborately modulated by modifying the substituent in aromatic acetylide and the conformations in tetraphosphine so as to achieve cyan, green, green-yellow, yellow, and orange-red emission.

15.
Tumour Biol ; 37(1): 1079-89, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26271667

RESUMO

LncRNA has provided an important new perspective regarding gene regulation. Both the expression and activation of EGFR have been proven to be under the tight control of the GHR pathway. EGFR-AS1 has been found to inhibit the expression of EGFR. GHR-siRNA and EGFR-AS1-siRNA were transfected into HCC cell lines, and a series of WB, q-PCR, and IF experiments was conducted to evaluate whether EGFR-AS1 participated in the regulation of GHR and EGFR. We found that impeded expression of GHR decreased the expression of EGFR and EGFR-AS1 in vivo and in vitro. Then, it was verified that EGFR and EGFR-AS1 were relatively upregulated in HCC tissue, and they were significantly related to some clinical characteristics and patient prognosis. Furthermore, EGFR-AS1 was determined to promote HCC development by improving the ability of invasion and proliferation of HCC cells in vitro, and it was also found to affect the cell cycle. Our study identified that EGFR-AS1 may promote HCC genesis and development. EGFR-AS1 may act as a prognostic factor in HCC. More importantly, we observed that the inhibition of EGFR-AS1 in HCC cells significantly impeded cell proliferation and invasion in vivo, which might provide a potential possibility for targeted therapy of HCC.


Assuntos
Carcinoma Hepatocelular/genética , Proteínas de Transporte/genética , Receptores ErbB/genética , Regulação Neoplásica da Expressão Gênica , Neoplasias Hepáticas/genética , RNA Longo não Codificante/genética , Animais , Carcinoma Hepatocelular/mortalidade , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Modelos Animais de Doenças , Transição Epitelial-Mesenquimal , Feminino , Perfilação da Expressão Gênica , Humanos , Neoplasias Hepáticas/mortalidade , Neoplasias Hepáticas/patologia , Masculino , Camundongos , Camundongos Knockout , Metástase Neoplásica , Prognóstico , Carga Tumoral , Regulação para Cima
16.
Med Sci Monit ; 22: 4073-4081, 2016 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-27794206

RESUMO

BACKGROUND The aim of this study was to explore effects of microRNA-200c regulating TGF-ß/Smad3 pathway by targeting Zeb1 on the occurrence and development of hypospadias and to evaluate the relationship between microRNA-200c and occurrence of hypospadias. MATERIAL AND METHODS Pregnant rats with a gestational age of 12 days were allocated into 2 groups; one received gavage of DEHP-contained soybean oil (1 ml/day, 8 days; Group A) and the other had gavage of normal soybean oil (1 ml/day, 8 days; Group B). Baby rats with hypospadias from Group A were assigned to the model group (n=20) and healthy baby rats from Group B were assigned to the control group (n=20). Real-time quantitative polymerase chain reaction (qRT-PCR), immunohistochemistry and Western blot analysis were performed to detect microRNA-200c, Zeb1, TGF-ß, and Smad3 mRNA and protein expressions in the model group (n=20) and the control group (n=20). The relationship between microRNA-200c and Zeb1 was detected using a dual-luciferase reporter gene experiment. After the in vitro intervention experiment in fetal rat penises, Western blot was used to detect the expression of Zeb1, TGF-ß, and Smad3. RESULTS In the model group, microRNA-200c was expressed at a low level, and microRNA-200c expression in control group was 2.1 times higher than in the model group (P<0.05). When compared with the control group, mRNA expressions, protein expressions, and positive rates of Zeb1, TGF-ß, and Smad3 were higher in the model group (all P<0.01). Luciferase gene report determined that Zeb1 is a target gene of microRNA-200c. The in vitro intervention experiment in fetal rat penises found that a high concentration of microRNA-200c inhibited hypospadias occurrence by suppressing the expression of Zeb1, TGF-ß, and Smad3. CONCLUSIONS MicroRNA-200c was expressed in hypospadias penis tissues at low levels and was negatively correlated with Zeb1 expression. MicroRNA-200c up-regulated Zeb1 expression to regulate the TGF-ß/Smad3 pathway, which led to the occurrence of hypospadias.


Assuntos
Hipospadia/genética , MicroRNAs/genética , MicroRNAs/metabolismo , Animais , Regulação para Baixo , Genes Homeobox , Hipospadia/metabolismo , Imuno-Histoquímica , Masculino , RNA Mensageiro/metabolismo , Ratos , Transdução de Sinais , Proteína Smad3/genética , Proteína Smad3/metabolismo , Fatores de Transcrição/metabolismo , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/metabolismo , Regulação para Cima , Homeobox 1 de Ligação a E-box em Dedo de Zinco/metabolismo
17.
Chemistry ; 21(12): 4712-20, 2015 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-25393379

RESUMO

Two L-phenylalanine derivatives with 5,8-bis(2-(carbazol-3-yl)vinyl)quinoxaline (PCQ) and 5,8-bis[2-(carbazol-3-yl)]-2,3-dimethylquinoxaline (DCQ) as fluorophores were synthesized, and their photophysical properties were measured and compared. The two compounds were found to gelate some organic solvents and self-assemble into 1D nanofibers in gels. The wet gel of PCQ emitted a weak orange fluorescence, but the DCQ gel had a strong green one. This result can be due to the presence of two methyl groups and the nonplanar conformation of fluorophore in DCQ. The gel film of DCQ also showed significantly stronger fluorescence than that of PCQ. Thus, the wet gel and xerogel film of DCQ were selected to study their sensing properties to acids. The yellow wet gel of DCQ transformed into a brown sol upon the addition of 0.2 equiv trifluoroacetic acid (TFA), accompanied by emission quenching. The xerogel film of DCQ rapidly responded to volatile acids, such as TFA, HCl, and HOAc. The fluorescence of the xerogel film was gradually quenched with increased concentration of volatile acid vapors. The fibrous film exhibited low detection limits for volatile acid. The detection limits of the thin films for TFA, HCl, and HOAc reached 43, 122, and 950 ppb, respectively.

18.
Org Biomol Chem ; 13(10): 2986-98, 2015 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-25620572

RESUMO

A series of new triphenylamine functionalized ß-diketones 1­3 and their difluoroboron complexes 1B­3B were synthesized. They exhibited strong intramolecular charge transfer (ICT) emission. It was found that their self-assembling properties depended on the molecular structures. For example, compounds 1 and 1B, in which only one ß-diketone or difluoroboron ß-diketone unit was linked to triphenylamine, showed better gelation abilities directed by π­π interaction. Although bis-ß-diketone substituted triphenylamine 2 could not form organogels, its difluoroboron complex 2B could gel DMSO due to the strong dipole­dipole interactions. Compound 3 could form gels in polar solvents, while 3B formed gels in nonpolar solvents. Notably, the asymmetric gelators 1, 1B and 2B exhibited AIEE behaviors during the gelation. Although the emission of the symmetric compounds 3 and 3B decreased to a certain degree upon gelation, the obtained gels still gave strong emission. The gels formed from 1 and 3 emitted strong green light and those based on 1B­3B emitted strong orange or red light. These highly luminescent materials might have potential applications in emitting devices and fluorescent sensors.


Assuntos
Aminas/química , Boro/química , Cetonas/química , Boranos/química , Corantes/química , Simulação por Computador , Éteres/química , Corantes Fluorescentes/química , Flúor/química , Géis/química , Ligantes , Luz , Luminescência , Espectroscopia de Ressonância Magnética , Oscilometria , Solventes/química , Espectrometria de Fluorescência , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Raios Ultravioleta , Difração de Raios X
19.
J Am Chem Soc ; 136(52): 17938-41, 2014 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-25495563

RESUMO

The hydrolysis of Ln(ClO4)3 in the presence of acetate leads to the assembly of the three largest known lanthanide-exclusive cluster complexes, [Nd104(ClO4)6(CH3COO)60(µ3-OH)168(µ4-O)30(H2O)112]·(ClO4)18·(CH3CH2OH)8·xH2O (1, x ≈ 158) and [Ln104(ClO4)6(CH3COO)56(µ3-OH)168(µ4-O)30(H2O)112]·(ClO4)22·(CH3CH2OH)2·xH2O (2, Ln = Nd; 3, Ln = Gd; x ≈ 140). The structure of the common 104-lanthanide core, abbreviated as Ln8@Ln48@Ln24@Ln24, features a four-shell arrangement of the metal atoms contained in an innermost cube (a Platonic solid) and, moving outward, three Archimedean solids: a truncated cuboctahedron, a truncated octahedron, and a rhombicuboctahedron. The magnetic entropy change of ΔS(m) = 46.9 J kg(-1) K(-1) at 2 K for ΔH = 7 T in the case of the Gd104 cluster is the largest among previously known lanthanide-exclusive cluster compounds.

20.
Org Biomol Chem ; 12(32): 6134-44, 2014 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-25008371

RESUMO

New indolocarbazole derivatives emitting strong blue light have been synthesized. It is found that the strong π­π interactions between indolocarbazoles 4­6 without long carbon chains lead to the formation of crystal or crystal-like aggregates. We have previously found that tert-butyl could tune the strength of π­π interactions between carbazole units and the organogels were obtained from tert-butyl substituted carbazoles directed by balanced π­π interactions. Herein, hexadecyl groups were introduced into N-positions of indolocarbazoles in order to reduce the strength of π­π interactions between indolocarbazoles, and compounds 7­9 were prepared. It is interesting that compounds 8 and 9 could form stable organogels in alcohols, acetone, DMSO, and so on, upon ultrasound stimulation. Combined with the results of electronic spectra, XRD patterns and the optimized molecular length based on the semiempirical (AM1) calculations, we suggested the molecular packing modes in gel states, in which the lamellar structures were involved. Although the fluorescence emission of indolocarbazoles 8 and 9 decreased during the gel formation to some extent, the obtained gel nanofibers still emitted strong blue light and the fluorescence emission of the film based on xerogel 9 decreased significantly upon exposure to gaseous TNT. It meant that the xerogels based on indolocarbazoles could be used as fluorescent sensors for detecting vapors of explosives.

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