Banti Baishya , Amit Kumar Pradhan , Saurav Paul , Manoj Kumar Paul
{"title":"对称液晶二聚体上的极性末端取代基:合成、光物理研究、介形和DFT研究","authors":"Banti Baishya , Amit Kumar Pradhan , Saurav Paul , Manoj Kumar Paul","doi":"10.1016/j.molliq.2025.128077","DOIUrl":null,"url":null,"abstract":"<div><div>A novel symmetrical liquid crystal dimer has been reported featuring a three-ring rod-shaped monomer with methylene ether-linked flexible spacers and different terminal polar substituents. The presence of lateral bulky methoxy groups in dimer molecules enhances intermolecular interactions and improves mesophase stability. The photophysical, thermal stability, liquid crystalline behaviour, and chemical reactivity parameters of dimers have been highlighted. The compounds show good thermal stability, among them presence of trifluorocarbon in the dimer shows higher thermal stability. The polar dimers are fluorescent with a large Stokes shift (∼8353–11,912 nm) and interesting photophysical behaviour in solution and solid thin films. The optical band gap of the dimer molecule in the solution is in the range of a semiconductor (2.1–2.8 eV), whereas the dimer <strong>4FV-6</strong> is found to exhibit the lowest value in solid thin films (1.9 eV). Their fluorescence quantum yield is greatly affected by concentration and solvent polarity, signifying higher fluorescence efficiency. All dimers exhibited a broad range of enantiotropic nematic phases, except fluoro-substituted dimers exhibit additional enantiotropic N<sub>x</sub> with the lowest clearing temperature. A DFT study explored their structural and electronic properties, including geometry optimization and TDDFT, CDFT, and ESP analyses. TDDFT revealed solvent-dependent redshifts in absorption spectra, with polar solvents stabilising excited states. Dipole moment and reactivity analyses showed <strong>4CNV-6</strong> had the highest polarity, while <strong>4NO</strong><sub><strong>2</strong></sub><strong>V-6</strong> was most electrophilic.</div></div>","PeriodicalId":371,"journal":{"name":"Journal of Molecular Liquids","volume":"434 ","pages":"Article 128077"},"PeriodicalIF":5.3000,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Polar terminal substituent on symmetrical liquid crystal dimers: Synthesis, photophysical studies, mesomorphism and DFT studies\",\"authors\":\"Banti Baishya , Amit Kumar Pradhan , Saurav Paul , Manoj Kumar Paul\",\"doi\":\"10.1016/j.molliq.2025.128077\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>A novel symmetrical liquid crystal dimer has been reported featuring a three-ring rod-shaped monomer with methylene ether-linked flexible spacers and different terminal polar substituents. The presence of lateral bulky methoxy groups in dimer molecules enhances intermolecular interactions and improves mesophase stability. The photophysical, thermal stability, liquid crystalline behaviour, and chemical reactivity parameters of dimers have been highlighted. The compounds show good thermal stability, among them presence of trifluorocarbon in the dimer shows higher thermal stability. The polar dimers are fluorescent with a large Stokes shift (∼8353–11,912 nm) and interesting photophysical behaviour in solution and solid thin films. The optical band gap of the dimer molecule in the solution is in the range of a semiconductor (2.1–2.8 eV), whereas the dimer <strong>4FV-6</strong> is found to exhibit the lowest value in solid thin films (1.9 eV). Their fluorescence quantum yield is greatly affected by concentration and solvent polarity, signifying higher fluorescence efficiency. All dimers exhibited a broad range of enantiotropic nematic phases, except fluoro-substituted dimers exhibit additional enantiotropic N<sub>x</sub> with the lowest clearing temperature. A DFT study explored their structural and electronic properties, including geometry optimization and TDDFT, CDFT, and ESP analyses. TDDFT revealed solvent-dependent redshifts in absorption spectra, with polar solvents stabilising excited states. Dipole moment and reactivity analyses showed <strong>4CNV-6</strong> had the highest polarity, while <strong>4NO</strong><sub><strong>2</strong></sub><strong>V-6</strong> was most electrophilic.</div></div>\",\"PeriodicalId\":371,\"journal\":{\"name\":\"Journal of Molecular Liquids\",\"volume\":\"434 \",\"pages\":\"Article 128077\"},\"PeriodicalIF\":5.3000,\"publicationDate\":\"2025-06-30\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Molecular Liquids\",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0167732225012541\",\"RegionNum\":2,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Molecular Liquids","FirstCategoryId":"92","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0167732225012541","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
Polar terminal substituent on symmetrical liquid crystal dimers: Synthesis, photophysical studies, mesomorphism and DFT studies
A novel symmetrical liquid crystal dimer has been reported featuring a three-ring rod-shaped monomer with methylene ether-linked flexible spacers and different terminal polar substituents. The presence of lateral bulky methoxy groups in dimer molecules enhances intermolecular interactions and improves mesophase stability. The photophysical, thermal stability, liquid crystalline behaviour, and chemical reactivity parameters of dimers have been highlighted. The compounds show good thermal stability, among them presence of trifluorocarbon in the dimer shows higher thermal stability. The polar dimers are fluorescent with a large Stokes shift (∼8353–11,912 nm) and interesting photophysical behaviour in solution and solid thin films. The optical band gap of the dimer molecule in the solution is in the range of a semiconductor (2.1–2.8 eV), whereas the dimer 4FV-6 is found to exhibit the lowest value in solid thin films (1.9 eV). Their fluorescence quantum yield is greatly affected by concentration and solvent polarity, signifying higher fluorescence efficiency. All dimers exhibited a broad range of enantiotropic nematic phases, except fluoro-substituted dimers exhibit additional enantiotropic Nx with the lowest clearing temperature. A DFT study explored their structural and electronic properties, including geometry optimization and TDDFT, CDFT, and ESP analyses. TDDFT revealed solvent-dependent redshifts in absorption spectra, with polar solvents stabilising excited states. Dipole moment and reactivity analyses showed 4CNV-6 had the highest polarity, while 4NO2V-6 was most electrophilic.
期刊介绍:
The journal includes papers in the following areas:
– Simple organic liquids and mixtures
– Ionic liquids
– Surfactant solutions (including micelles and vesicles) and liquid interfaces
– Colloidal solutions and nanoparticles
– Thermotropic and lyotropic liquid crystals
– Ferrofluids
– Water, aqueous solutions and other hydrogen-bonded liquids
– Lubricants, polymer solutions and melts
– Molten metals and salts
– Phase transitions and critical phenomena in liquids and confined fluids
– Self assembly in complex liquids.– Biomolecules in solution
The emphasis is on the molecular (or microscopic) understanding of particular liquids or liquid systems, especially concerning structure, dynamics and intermolecular forces. The experimental techniques used may include:
– Conventional spectroscopy (mid-IR and far-IR, Raman, NMR, etc.)
– Non-linear optics and time resolved spectroscopy (psec, fsec, asec, ISRS, etc.)
– Light scattering (Rayleigh, Brillouin, PCS, etc.)
– Dielectric relaxation
– X-ray and neutron scattering and diffraction.
Experimental studies, computer simulations (MD or MC) and analytical theory will be considered for publication; papers just reporting experimental results that do not contribute to the understanding of the fundamentals of molecular and ionic liquids will not be accepted. Only papers of a non-routine nature and advancing the field will be considered for publication.