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Organic Transistor Based on Cyclopentadithiophene-Benzothiadiazole Donor-Acceptor Copolymer for the Detection and Discrimination between Multiple Structural Isomers
摘要： Distinguishing structural isomers is a critical and challenging task for biotechnology, chemical industry, and environmental monitoring. Approaches currently available are limited in terms of selectivity and simplicity. In this paper, a highly sensitive organic field-effect transistor (OFET) using the cyclopentadithiophene-benzothiadiazole (CDT-BTZ) copolymers as a semiconductor is presented for easy and selective detection of different families of structural isomers, as well as between different isomers within each family. High accuracy discrimination is achieved over a range of concentrations using only a single sensing parameter derived from the OFET characteristic transfer curve. As a reference, other homopolymer- and donor–acceptor copolymer-based OFET sensors are examined but do not have an equivalent sensing performance to that of the CDT-BTZ-based OFETs. Investigating the link between isomer absorption and swelling, supramolecular order and energy levels of the active layer reveals a unique effect of each isomer on the energy bands of the semiconducting polymer.
关键词： isomers,donor–acceptor copolymers,gas sensor,organic field-effect transistor,xylenes
更新于2025-09-23 15:23:52
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Online photochemical derivatization enables comprehensive mass spectrometric analysis of unsaturated phospholipid isomers
摘要： Mass spectrometry-based lipidomics is the primary tool for the structural analysis of lipids but the effective localization of carbon–carbon double bonds (C=C) in unsaturated lipids to distinguish C=C location isomers remains challenging. Here, we develop a large-scale lipid analysis platform by coupling online C=C derivatization through the Paternò-Büchi reaction with liquid chromatography-tandem mass spectrometry. This provides rich information on lipid C=C location isomers, revealing C=C locations for more than 200 unsaturated glycerophospholipids in bovine liver among which we identify 55 groups of C=C location isomers. By analyzing tissue samples of patients with breast cancer and type 2 diabetes plasma samples, we find that the ratios of C=C isomers are much less affected by interpersonal variations than their individual abundances, suggesting that isomer ratios may be used for the discovery of lipid biomarkers.
关键词： C=C location isomers,biomarker discovery,Paternò-Büchi reaction,mass spectrometry,lipidomics
更新于2025-09-23 15:23:52
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Bay-Linked Perylenediimides are Two Molecules in One: Insights from Ultrafast Spectroscopy, Temperature Dependence, and Time-Dependent Density Functional Theory Calculations
摘要： Bay-linked di-perylenediimide (di-PDI) molecules are finding increasing use in organic electronics due to their steric hindrance that 'twists' the two monomer units relative to one another, decreasing molecular aggregation. In this paper we explore the electronic spectroscopy and ultrafast dynamics of the singly-linked β-β-S-di-PDI (2,9'-di(undecan-5-yl)-2',9-di(undecan-6-yl)-[5,5'-bianthra[2,1,9-def:6,5,10-d'e'f']diisoquinolin]-1,1',3,3',8,8',10,10'(2H,2'H,9H,9'H)-octaone). Excitation-emission spectroscopy reveals two distinct emitting species, which are further characterized by time-dependent density functional theory (TD-DFT), demonstrating that the bay-linked PDI dimers exist in two geometrical conformations. These conformations are an 'open' geometry, where the two monomer sub-units are oriented nearly at right angles, giving them more J-like coupling, and a 'closed' geometry, in which the two monomer sub-units are nearly π-stacked, resulting in more H-like coupling. Given the extent of through-space and through-bond coupling, however, neither di-PDI conformer can be well-described simply in terms of independently-coupled monomers; instead, a full quantum chemistry description is required to understand the electronic structure of this molecule. Temperature-dependent experiments and the TD-DFT calculations indicate that the 'closed' conformer is ～70 meV more stable than the 'open' conformer, so that both conformers are important to the behavior of the molecule at room temperature and above. We use a combination of steady-state and femtosecond transient absorption and emission spectroscopies to globally fit the multiple electronic transitions underlying the spectra of both the 'closed' and 'open' conformers, which agree well with the TD-DFT calculations. The fact that di-PDI molecules are molecular species that adopt two distinct quasi-independent chemical identities has important ramifications for charge trapping and mobility in the organic electronic devices employing these materials.
关键词： TD-DFT calculations,ultrafast spectroscopy,conformational isomers,organic electronics,Bay-linked perylenediimides
更新于2025-09-23 15:22:29
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Raman high-pressure study of butane isomers up to 40 GPa
摘要： Raman spectroscopy studies on n and i-butane were performed at pressures of up to 40 GPa at ambient temperatures using the DAC technique. Normal butane undergoes two phase transitions at 1.9(5) GPa and 2.9(5) GPa and isobutane at 2.7(5) GPa and 3.5(5) GPa. These phase transitions were identi?ed based on observations of the splitting Raman modes and the appearance or disappearance of particular Raman peaks. Our results demonstrate the complex, high-pressure behavior of butane isomers.
关键词： Raman spectroscopy,high-pressure,DAC technique,phase transitions,butane isomers
更新于2025-09-23 15:21:01
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Ideal alloys of two donor isomers with non-covalently conformational locking for ternary organic solar cells
摘要： Ternary organic solar cells (OSCs) based on the alloy model have great potential in maximizing the improvement of device performance due to the probability of simultaneously enhancing the photocurrent through morphology optimization and improving open circuit voltage (Voc) by energy level adjustment. However, rationally designing compatible materials and constructing an effective alloy remain difficult. In this manuscript, two donor isomers, BT-TO-ID and BT-OT-ID with non-covalently conformational locking of alkoxy groups at different position, were designed and synthesized to obtain an ‘‘ideal alloy’’. A linearly tunable Voc was observed between the Voc limitation of binary blends with the changes of the composition across the full range, indicating the behavior of an ideal alloy in the ternary blends. A face-on molecular packing and an appropriate phase separation was observed in the ternary blends due to the strong interactions between the two isomers, which facilitated charge transport and charge recombination suppression. Notable improvements of 76% and 29% in device performance were obtained for the ternary blends compared with BT-OT-ID based and BT-OT-ID based binary devices, respectively. Therefore, this work provided a probable molecular design strategy to guide the construction of an effective alloy in ternary OSCs.
关键词： Open circuit voltage,Non-covalently conformational locking,Alloy model,Device performance,Molecular packing,Phase separation,Ternary organic solar cells,Donor isomers
更新于2025-09-23 15:21:01
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A novel nematic tri-carbazole as a hole-transport material for solution-processed OLEDs
摘要： Two structural isomers of alkyl-substituted tri-carbazoles were synthesised to study the effect of the substitution pattern on their liquid crystalline behaviour and conductivity and performance in test OLEDs. The isomer with a 2,7-disubstitution pattern in the central carbazole exhibits a monotropic nematic phase, a high conductivity up to 10 Cd A?1 and is suitable as a hole-transport material for solution-processed OLEDs, achieving a high efficiency. The tri-carbazole isomer with a 3,6-substitution pattern, in the central carbazole, does not exhibit observable liquid crystalline behaviour, exhibits conductivity values two orders of magnitude lower than that of its 2,7-disubstituted isomer and performs poorly in OLEDs with the same configuration. Two structural isomers of alkyl-substituted tri-carbazoles A and B exhibit significantly different liquid crystalline behaviour, conductivity and performance in test OLEDs dependent upon their molecular shape.
关键词： nematic mesophases,hole transport materials,Tri-carbazole liquid crystalline isomers,solution-processed OLED
更新于2025-09-23 15:21:01
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Terahertz Spectral of Enantiomers and Racemic Amino Acids by Time-Domain-Spectroscopy Technology
摘要： The absorption spectra of four amino acids were studied. These spectra are obtained by terahertz time-domain spectroscopy (TDS) technique. The four amino acids are alanine, methionine, leucine, and valine, respectively. The spectra of their enantiomers (L-, D-) and racemic compounds (DL-) were investigated. Although the two isomers have very similar structures, their absorption spectra are obviously different. The absorption coefficient of each structure is calculated by the density functional theory (DFT), and the simulated spectra of each structure are obtained. It is shown that the number of the calculated peaks is in good agreement with the experimental ones. The experimental spectra were compared with the theoretical spectra. The differences between the absorption spectra of isomers are presented, and the reasons for the differences were analyzed. The vibratory spectra of biomolecules were studied, and the correlation between molecular structure and function was further understood.
关键词： collective vibration,isomers,amino acids,density functional theory,terahertz time-domain spectroscopy
更新于2025-09-23 15:21:01
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Qualitative and Quantitative Distinction of <i>ortho</i> -, <i>meta</i> -, and <i>para</i> -Fluorotoluene by Means of Chirped Femtosecond Laser Ionization
摘要： Femtosecond-laser ionization mass spectrometry (fs-LIMS) is demonstrated to be a powerful analytical method providing access to the qualitative distinction of structural isomers of ortho-, meta-, and para-fluorotoluene. The key point of the approach presented is a systematic variation of the spectral phase of the fs-laser pulses, which characteristically affects the fragmentation pattern observed in the mass spectra. Variation of the linear chirp parameter is also helpful for rationalizing the fragmentation mechanism. Ultimately two ternary mixtures of the three title isomers are quantitatively analyzed in situ with an accuracy of 5% for the molar fractions.
关键词： structural isomers,Femtosecond-laser ionization mass spectrometry,fragmentation pattern,spectral phase,quantitative analysis,fluorotoluene
更新于2025-09-23 15:19:57
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<i>N</i> -Cyanoimine as an electron-withdrawing functional group for organic semiconductors: example of dihydroindacenodithiophene positional isomers
摘要： Manipulating frontier molecular orbitals by chemical design is one of the chief aspects of organic electronics. For applications in the field of n-type organic field-effect transistors (OFET), depressing the LUMO energy level is particularly important to ensure efficient charge injection. In this work, we report the incorporation of electron-withdrawing cyanoimine functional groups on the bridges of dihydroindacenodithiophene regioisomers. Cyanoimines are barely known in the field of organic electronics but herein have been found to be highly efficient in depressing the LUMO energy level of an organic semiconductor and can thus be envisaged as an attractive alternative to widely known electron-withdrawing units such as dicyanovinylene. This work focuses on a detailed structure–property relationship study, including the incorporation in n-type OFETs, of two dihydroindacenodithiophene regioisomers bearing two cyanoimine groups either in a syn- or an anti-configuration. As far as we know, this work is only the second example reported to date on N-cyanoimines incorporated in n-type OFETs, and shows the potential of these functional groups in organic electronics.
关键词： organic semiconductor,dihydroindacenodithiophene,electron-withdrawing group,positional isomers,N-cyanoimine,n-type OFET
更新于2025-09-19 17:15:36
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Rational design of high efficiency green to deep red/near-infrared emitting materials based on isomeric donor–acceptor chromophores
摘要： A family of compounds TPA-BT-Q, TPA-pyT-N-naph, TPA-N-pyT-naph, and DPA-py-N-BT-naph with the isomeric donor-acceptor conjugation framework were designed and synthesized, and their structure-property relationships, theoretical calculations, and photophysical and electrochemical characteristics were investigated. These isomeric chromophores showed significantly different photophysical properties. Emission wavelengths spanning from green to near-infrared region were observed in different solvents with high photoluminescence quantum yield, exceeding 90% in low polarity solvents and 44–88% in blend films. Organic light-emitting devices displayed strong electroluminescence with emission peaks at 592, 660, 630, and 580 nm; maximum current efficiencies of 7.92, 2.93, 3.56, and 15.37 cd/A; maximum power efficiencies of 4.21, 1.56, 1.81, and 8.24 lm/W; and maximum external quantum efficiencies of 3.15%, 2.75%, 2.66%, and 5.33% for TPA-BT-Q, TPA-pyT-N-naph, TPA-N-pyT-naph, and DPA-py-N-BT-naph doped OLEDs, respectively.
关键词： Donor-Accepter,Near-Infrared,Isomers,Photophysics,Electroluminescence
更新于2025-09-19 17:15:36