Effect of substituent on UV–visible absorption and photostability of liquid crystals: DFT study

Praveen, P. Lakshmi; Ojha, Durga P.

doi:10.1080/01411594.2013.852195

Cited by 26 publications

(4 citation statements)

References 21 publications

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“…The CAM‐B3LYP/6‐311G+(2d,p) level of theory was used to calculate the molecular orbital energies for the series of substituted benzimidazoles in this study. These parameters are known to vary with changing substituents [31] . For ease of comparison, the H‐substituent is used as a reference.…”

Section: Resultsmentioning

confidence: 99%

“…These parameters are known to vary with changing substituents. [31] For ease of comparison, the H-substituent is used as a reference. Incorporating EDGs in the molecular structure decrease the HOMO-LUMO energy gap (Table 4), and this is consistent with the results obtained in the literature, [32] while the EDGs cause a decrease.…”

Section: Comparison Between the Ground And Electronically Excited Sta...mentioning

confidence: 99%

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Theoretical Study of the Photophysical and Photochemical Properties of 1H‐Benzimidazole and 2‐Ethyl‐7‐nitro‐5‐Substituted 1H‐Benzimidazoles

Udofia,

Oloba‐Whenu,

Ogunbayo

et al. 2023

ChemistrySelect

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Theoretical study of the photophysical/photochemical properties of 1H‐benzimidazole and its derivatives was carried out using APFD, B3LYP, CAM‐B3LYP and PBE0 density functionals with 6‐311+G(2d,p) basis set. The effects of ethanol, 1,4‐dioxane, acetonitrile and water was investigated by means of Integral Equation Formalism of the Polarizable Continuum Model (IEPCM) in the framework of Self‐Consistent Reaction Field (SCRF). The results obtained show that S2 state of the 1H‐benzimidazole molecule is more acidic than the S0 state as the N5−H11 bond length increased to ~ 1.01 Å. At B3LYP/6‐311+G(2d,p) level of theory, the excitation energy of 1H‐bensimidazole molecule in ethanol from S0 to the S2 state was calculated to be 273 nm (4.54 eV). The electronic energy for this transition was calculated to be 0.131 a.u. and observed to occur between π→π* orbitals. Calculations with the PBE0, APFD and B3LYP functionals reproduced the experimental dipole moment in 1,4‐dioxane, with values of 4.09, 4.09 and 4.07 Debye respectively. However, the dipole moments of the 2‐ethyl‐7‐nitro‐5‐substituted‐1H‐benzimidazoles were calculated to be higher for electron donating groups (EDGs) than those bearing electron withdrawing groups (EWGs). In addition, the molecular polarizability was observed to increase with decreasing energy gap. Local excitation (LE) and charge‐transfer (CT) were observed to mediate the mechanisms of electronic excitation in 2‐ethyl‐7‐nitro‐5‐substituted‐1H‐benzimidazoles.

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Section: Resultsmentioning

confidence: 99%

Section: Comparison Between the Ground And Electronically Excited Sta...mentioning

confidence: 99%

Theoretical Study of the Photophysical and Photochemical Properties of 1H‐Benzimidazole and 2‐Ethyl‐7‐nitro‐5‐Substituted 1H‐Benzimidazoles

Udofia,

Oloba‐Whenu,

Ogunbayo

et al. 2023

ChemistrySelect

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“…In general, these transitions are influenced by different factors, such as the conjugation length, degree of conjugation, and the different substituents. These factors effect on the lowest occupied molecular orbital (LUMO) and the highest unoccupied molecular orbitals (HOMO) through them absorption transition occur [28][29][30][31][32][33] 2.2 TGA analysis for the dyes…”

Section: Absorption Measurementsmentioning

confidence: 99%

Effect of polymeric dye network bonding on fluorescence thermometry for optical fiber temperature sensor

Mahmoud

Negm

Kana

et al. 2023

J Mater Sci: Mater Electron

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Fluorescein and two of its derivatives (allyl Fluorescein and diallyl Fluorescein) are solidified in glycidyl methacrylate (GMA) polymer matrix for the development of fluorescence-based fiber optically temperature sensor. These two Fluorescein derivatives were investigated in order to study the influence of degree of covalent bonds to GMA polymer backbone on Fluorescein dye sensitivity for temperature changes. The dye-polymer discs have been investigated separately in order to determine their sensitivities in the temperature ranges from 10 to 300 K and from 297 to 370 K. The dye-polymer discs are excited by Argon ion laser (488 nm, 50 mW) and the fluorescence intensity is measured using lock-in technique. Below room-temperature Fluorescein dye in (GMA) polymer shows very weak sensitivity toward temperature changes in the range from 10 up to 297 K. The fluorescence intensity peaks of allyl Fluorescein dye in (GMA) polymer exhibit tendency for decreasing slightly, while the dye is warmed up from 40 to 245 K. Also, the fluorescence intensity peaks of diallyl Fluorescein dye in (GMA) are reported in the temperature range from 49 to 300 K. The intensity peak values decrease gradually, whereas at the temperature 171 and 229 K the peaks show hazard change. Above room temperature, the fluorescence intensity peaks decrease with increasing temperature in the temperature range from 302 to 370 K.

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“…For example, Cao has investigated the substituent effect on the UV absorption energies of 1,4‐disubstituted benzenes and benzylideneaniline derivatives with imine bridge group (C═N) . Praveen has studied the effect of substituent on the UV‐visible absorption and photostability of liquid crystals. The relationships between the UV absorption energy and the molecular structure are distinctive for different compound systems.…”

Section: Introductionmentioning

confidence: 99%

Substituent effects on the UV absorption energy of 2,5‐disubstituted pyrimidines

Yuan

Chen

et al. 2018

J of Physical Organic Chem

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Pyrimidine-containing molecules have been extensively investigated in organic light emitting devices (OLEDs), solar cells, liquid crystals, and so on due to their perfect photoelectric properties. Ultraviolet (UV) absorption is one of the interesting photoelectric properties. Systematical study of the substituent effects on the UV absorption energy of pyrimidine derivatives will guide to design functional molecules with specific photoelectric properties. In this paper, thirty-seven 2-X-5-Y pyrimidines with various substituents (X/Y=NH 2 , CH 3 , OCH 3 , NMe 2 , CF 3 , NO 2 , Cl, Br, I) were synthesized, and their UV spectra were recorded in anhydrous ethanol. The maximum absorption wavelength λ max (nm) were obtained and converted to wavenumber ν max (cm -1 ) (ν max = 1/λ max ) for quantitative structure-property relationship study. Hammett parameters (σ, σ F , σ R ), electronegativity (χ), the excited-state substituent effect parameter (σ ex CC ), and the heavy atom effect indicator (D) were employed as descriptors characterizing the molecular structure. By stepwise regression, a 5-descriptor linear regression model was built as ν max = 35 864.8122 + 6743.7901σ R (X) + 8587.9937σ R (Y) − 2042.7280Δσ 2 + 1106.0034D(X) + 1451.8873χ(X) (R = 0.9861, S = 693.70, ARD = 1.49%, F = 218.68, R cv = 0.9775, S cv = 881.25, ARD cv = 1.82%, n = 37). The model is proved of good stability and predictive performance by leave-one-out cross validation. Compared with the benzylideneaniline derivatives with C═N bridge group, the substituent effects on the UV absorption energy of 2,5-disubstituted pyrimidines are quite different and much more complex. KEYWORDS 2,5-disubstituted pyrimidine, quantitative structure-property relationship, substituent effect, UV absorption

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Effect of substituent on UV–visible absorption and photostability of liquid crystals: DFT study

Cited by 26 publications

References 21 publications

Theoretical Study of the Photophysical and Photochemical Properties of 1H‐Benzimidazole and 2‐Ethyl‐7‐nitro‐5‐Substituted 1H‐Benzimidazoles

Theoretical Study of the Photophysical and Photochemical Properties of 1H‐Benzimidazole and 2‐Ethyl‐7‐nitro‐5‐Substituted 1H‐Benzimidazoles

Effect of polymeric dye network bonding on fluorescence thermometry for optical fiber temperature sensor

Substituent effects on the UV absorption energy of 2,5‐disubstituted pyrimidines

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