Herein, we report the quantum chemical results based on density functional theory for the polarizability (α) and first hyperpolarizability (β) values of diacetylene-functionalized organic molecules (DFOM) containing an electron acceptor (A) unit in the form of nitro group and electron donor (D) unit in the form of amino group. Six DFOM 1–6 have been designed by structural tailoring of the synthesized chromophore 4,4′-(buta-1,3-diyne-1,4-diyl) dianiline (R) and the influence of the D and A moieties on α and β was explored. Ground state geometries, HOMO-LUMO energies, and natural bond orbital (NBO) analysis of all DFOM (R and 1–6) were explored through B3LYP level of DFT and 6-31G(d,p) basis set. The polarizability (α), first hyperpolarizability (β) values were computed using B3LYP (gas phase), CAM-B3LYP (gas phase), CAM-B3LYP (solvent DMSO) methods and 6-31G(d,p) basis set combination. UV-Visible analysis was performed at CAM-B3LYP/6-31G(d,p) level of theory. Results illustrated that much reduced energy gap in the range of 2.212–2.809 eV was observed in designed DFOM 1–6 as compared to parent molecule R (4.405 eV). Designed DFOM (except for 2 and 4) were found red shifted compared to parent molecule R. An absorption at longer wavelength was observed for 6 with 371.46 nm. NBO analysis confirmed the involvement of extended conjugation and as well as charge transfer character towards the promising NLO response and red shift of molecules under study. Overall, compound 6 displayed large <α> and βtot, computed to be 333.40 (a.u.) (B3LYP gas), 302.38 (a.u.) (CAM-B3LYP gas), 380.46 (a.u.) (CAM-B3LYP solvent) and 24708.79 (a.u.), 11841.93 (a.u.), 25053.32 (a.u.) measured from B3LYP (gas), CAM-B3LYP (gas) and CAM-B3LYP (DMSO) methods respectively. This investigation provides a theoretical framework for conversion of centrosymmetric molecules into non-centrosymmetric architectures to discover NLO candidates for modern hi-tech applications.
Abstract:We synthesized poly(N-isopropylacrylamide-co-acrylic acid) microgels with 1, 3, 5, and 7 mol percentage of acrylic acid. Silver nanoparticles were fabricated inside these microgels at room temperature. Pure microgels were characterized by Fourier transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS). Hybrid microgels were characterized by UV-Visible spectroscopy. The size of the silver nanoparticles increased with an increase in the content of acrylic acid. Catalytic activity of these hybrid microgels was investigated using UV-Visible spectrophotometry.Induction time decreased from 8.8 to 2.6 min and the value of apparent rate constant decreased from 0.226 to 0.109 min −1 , when the content of acrylic acid was increased from 1 to 7 mol %. This decrease in induction time was due to decrease in the surface area of nanoparticles present within the microgels with an increase in the feed contents of acrylic acid. The decrease in the value of apparent rate constant was due to an increase in the size of nanoparticles fabricated within the microgels with an increase in mol percentage of acrylic acid. The linear relation between apparent rate constant and feed contents of acrylic acid can be used for quantitative analysis of contents of acrylic acid present in polymer microgels.
Tetraphenylethylene
(TPE) can be used to construct fluorescent
probes with typical aggregation-induced emission (AIE) behavior for
next-generation sensing applications. McMurry coupling and Suzuki
cross coupling strategies provided the desired sensor thiophene-substituted
tetraphenylethylene (THTPE). The synthesized TPE analogues were characterized
by NMR spectroscopy and mass spectrometry. Maximum AIE of THTPE was
observed in 90% water (H2O/THF) content due to extensive
formation of aggregates. The AIE properties of THTPE have been utilized
for facile detection of nitroaromatic compounds (NACs) (1.0 nM) through
a fluorescence quenching mechanism. A paper strip adsorbed with the
AIE-based THTPE fluorophore is developed for rapid and convenient
detection of NAC-based analytes. Further, interaction of THTPE with
analytes is also studied via Gaussian software at the DFT/B3LYP/6-31G(d)
level of theory. Interaction energy, frontier molecular orbitals (FMOs),
and non-covalent interaction (NCI) analyses are studied by using the
same method. Computational results revealed that nitrobenzene (NB)
has the strongest interaction while 1,3-dinitrobenzene (DNB) exhibits
the least interaction with the sensor molecule. These computational
results clearly demonstrate good agreement with experimental data.
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