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Bichromophoric pyrazoline derivative with solvent-selective photoluminescence quenching
摘要： The quenching of fluorescence in the presence of chloromethanes, which is an unprecedented effect for pyrazolines, has been evidenced for the first time in the case of 1,3-diphenyl-5-{4-[(4-vinylbenzyl)oxy]phenyl}-4,5-dihydropyrazole. The detailed synthesis of this aryl trisubstituted pyrazoline that combines two chromophoric units in a non-conjugated manner is presented. The compound has been extensively characterized from a structural point of view, and its crystal structure has been determined by single crystal X-ray crystallography. The fluorescence study has evidenced the particular behavior of this pyrazoline derivative in solutions of chloromethanes, and the insight gained from the experimental data has been useful in elaborating a plausible fluorescence quenching mechanism. The investigated compound was modeled by Density Functional Theory (DFT) to point out the particularities of the electron transitions in gas phase as well as in the implicit solvents. Also, the HOMO-LUMO energy gap, mapped electrostatic potential, electronic density, dipole moment and polarizability have been reported for the pyrazoline derivative.
关键词： Fluorescence,Synthesis,Quenching,Molecular modelling,Bichromophore,Pyrazoline
更新于2025-09-23 15:22:29
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Molecular and excited state properties of photostable anthraquinone blue dyes for hydrophobic fibers
摘要： Synthetic dyes having high photostability on hydrophobic fibers such as poly(ethylene terephthalate) (PET) are of interest for use on textile substrates for outdoor applications. While much is known about photostable dyes developed for PET in the 1980s, owing to their viability for use in automobile interiors, little has been published on currently viable photostable disperse dyes. As part of an effort to help fill this void and to facilitate future photostable disperse dye design, the present study involved the use of experimental measurements and modelling studies to help characterize the molecular structures of commercially viable dyes for producing photostable colors on PET fibers, beginning with a pair of blue dyes. With the aid of HR-MS, 500 MHz 1H NMR, and X-ray crystallography, it was established that the two dyes are structural isomers having 1,5-(OH)2-anthraquinone (AQ) and 1,8-(OH)2-AQ base structures. It is proposed that the photostability of these dyes arises from the presence of multiple OH/NH groups ortho to the AQ C]O groups which enables them to dissipate excited state energy through intramolecular proton transfer. Further, using DFT-based molecular modelling studies, it was shown that the dye having the 1,5-(OH)2-AQ base structure has a lower ESOP than the isomeric dye having the 1,8-(OH)2-AQ base structure. Similarly, results from calculating Frontier HOMO and LUMO isosurfaces indicated that the LUMO lobes of the latter dye are larger, suggesting that this dye undergoes excitation faster than the 1,5-(OH)2-AQ isomer.
关键词： Molecular modelling,Anthraquinone disperse dyes,X-ray crystallography,Intramolecular H-bonding,Structural analysis
更新于2025-09-23 15:22:29
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Live-cell super-resolution microscopy reveals a primary role for diffusion in polyglutamine-driven aggresome assembly
摘要： The mechanisms leading to self-assembly of misfolded proteins into amyloid aggregates have been studied extensively in the test tube under well-controlled conditions. However, to what extent these processes are representative of those in the cellular environment remains unclear. Using super-resolution imaging of live cells, we show here that an amyloidogenic polyglutamine-containing protein first forms small, amorphous aggregate clusters in the cytosol, chiefly by diffusion. Dynamic interactions among these clusters limited their elongation and led to structures with a branched morphology, differing from the predominantly linear fibrils observed in vitro. Some of these clusters then assembled via active transport at the microtubule-organizing center and thereby initiated the formation of perinuclear aggresomes. Although it is widely believed that aggresome formation is entirely governed by active transport along microtubules, here we demonstrate, using a combined approach of advanced imaging and mathematical modeling, that diffusion is the principal mechanism driving aggresome expansion. We found that increasing surface area of the expanding aggresome increases the rate of accretion due to diffusion of cytosolic aggregates and that this pathway soon dominates aggresome assembly. Our findings lead to a different view of aggresome formation than that proposed previously. We also show that aggresomes mature over time, becoming more compacted as the structure grows. The presence of large perinuclear aggregates profoundly affects the behavior and health of the cell, and our super-resolution imaging results indicate that aggresome formation and development are governed by highly dynamic processes that could be important for the design of potential therapeutic strategies.
关键词： molecular modelling,protein aggregation,molecular imaging,passive transport,amyloid protein,aggresome formation,transport,live cell SIM,protein misfolding,molecular dynamics
更新于2025-09-23 15:21:21
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Synthesis of novel small-molecule fluorescently labeled probes for the in vitro imaging of KCa3.1 channels
摘要： In order to facilitate the in vitro visualization of KCa3.1 channel-expressing cells, novel small-molecule imaging probes were designed and developed. Senicapoc showing high affinity and excellent selectivity towards the KCa3.1 channels was selected as targeting component. Different BODIPY dyes (15 - 20) were synthesized and connected by a Cu-catalyzed azide alkyne [3+2]cycloaddition with propargyl ether derivative 8 of senicapoc yielding fluorescently labeled ligands 21 - 26 targeting KCa3.1 channels. The novel dimethylpyrrole-based imaging probes 25 and 26 allow staining of KCa3.1 ion channels in NSCLC cells following a simple, fast and efficient protocol. The specificity was shown by removing the punctate staining pattern by pre-incubation with senicapoc. The density of KCa3.1 channels detected with fluorescent probe 25 and by immunostaining was identical. The punctate structure of the labeled channels could be observed in living cells as well. Molecular modeling studies showed binding of the senicapoc targeting component towards the binding site within the ion channel and orientation of the linker with the dye along the inner surface of the ion channel.
关键词： labeled ligands,KCa3.1 channel,fluorescent probes,non-small cell lung cancer cells,molecular modelling,imaging agents,cycloaddition
更新于2025-09-23 15:19:57
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N-glycosylation state of TRPM8 protein revealed by terahertz spectroscopy and molecular modelling
摘要： TRPM8 member of the TRP superfamily of membrane proteins participates to various cellular processes ranging from Ca2+ uptake and cold sensation to cellular proliferation and migration. TRPM8 is a large tetrameric protein with more than 70% of its residues located in the cytoplasm. TRPM8 is N-glycosylated, with a single site per subunit. This work focuses on the N-glycosylation of TRPM8 channel that was previously studied by our group in relation to proliferation and migration of tumoral cells. Here, experimental data performed with deglycosylating agents assess that the sole glycosylation site contains complex glycans with a molecular weight of 2.5 kDa. The glycosylation state of TRPM8 in cells untreated and treated with a deglycosylating agent was addressed with Terahertz (THz) spectroscopy. Results show a clear difference between cells comprising glycosylated and deglycosylated TRPM8, the first presenting an increased THz absorption. Human TRPM8 was modelled using as templates the available TRPM8 and other TRPM channels structures. Glycosylations were modelled by considering two glycan structures with molecular weight close to the experiment: shorter and branched at the first sugar unit (glc1) and longer and unbranched (glc2). Simulation of THz spectra based on the molecular dynamics of unglycosylated and the two glycosylated TRPM8 models in lipid membrane and solvation box showed that glycan structure strongly influences the THz spectrum of the channel and of other components from the simulation system. Only spectra of TRPM8 with glc1 glycans were in agreement with the experiment, leading to the validation of glc1 glycan structure.
关键词： N-glycosylation,Terahertz spectroscopy,TRPM8,Molecular modelling,Membrane proteins
更新于2025-09-19 17:13:59
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Building Blocks for High‐Efficiency Organic Photovoltaics: Interplay of Molecular, Crystal, and Electronic Properties in Post‐Fullerene ITIC Ensembles
摘要： Accurate single-crystal X-ray diffraction data offer a unique opportunity to compare and contrast the atomistic details of bulk heterojunction photovoltaic small-molecule acceptor structure and packing, as well as provide an essential starting point for computational electronic structure and charge transport analysis. Herein, we report diffraction-derived crystal structures and computational analyses on the n-type semiconductors which enable some of the highest efficiency organic solar cells produced to date, 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (ITIC) and seven derivatives (including three new crystal structures: 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-propylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (ITIC-C3), 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(3-hexylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (m-ITIC-C6), and 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6,7-difluoro)-indanone))-5,5,11,11-tetrakis(4-butylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (ITIC-C4-4F). IDTT acceptors typically pack in a face-to-face fashion with π–π distances ranging from 3.28–3.95 ?. Additionally, edge-to-face packing is observed with S?π interactions as short as 3.21–3.24 ?. Moreover, ITIC end group identities and side chain substituents influence the nature and strength of noncovalent interactions (e.g. H-bonding, π–π) and thus correlate with the observed packing motif, electronic structure, and charge transport properties of the crystals. Density functional theory (DFT) calculations reveal relatively large nearest-neighbor intermolecular π-π electronic couplings (5.85–56.8 meV) and correlate the nature of the band structure with the dispersion interactions in the single crystals and core–end group polarization effects. Overall, this combined experimental and theoretical work reveals key insights into crystal engineering strategies for indacenodithienothiophene (IDTT) acceptors, as well as general design rules for high-efficiency post-fullerene small molecule acceptors.
关键词： density functional calculations,crystal structure,non-fullerene,molecular modelling,solar cells
更新于2025-09-11 14:15:04
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ECCD characterization of monotopically binding guests in host-guest complexes with a bis-(zinc porphyrin) tweezer
摘要： We have investigated the possibility to use a stiff-stilbene linked bisporphyrin tweezer with inherent helicity for Exciton-Coupled Circular Dichroism (ECCD) characterization of a series of monotopically binding amine guest molecules. CD signals were observed for a variety of monoamines at relatively low tweezer:amine (host:guest) ratios between 1:10 to 1:70. For the amines producing the most intense CD signals a binding stoichiometry of 1:2 was found. A likely explanation is the presence of guest-guest interactions in the complexes. This is supported by observing a correlation between CD signal intensity and magnitude of possible non-covalent binding between the guests, which we can divide into three groups showing no, moderate or strong response, respectively. Further support for this rationalization comes from molecular modelling.
关键词： absolute stereochemistry,molecular modelling,bis-porphyrin tweezers,monotopic binding,exciton-coupled circular dichroism
更新于2025-09-09 09:28:46