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Fulltext Chemically Modified Quinoidal Oligothiophenes for Enhanced Linear and Third-Order Nonlinear Optical Properties

Bibi A, Muhammad S, UrRehman S, Bibi S, Bashir S, Ayub K, et al.

ACS Omega, 2021 Sep 28;6(38):24602-24613.
PMID: 34604642 DOI: 10.1021/acsomega.1c03218

In the present investigation, quantum chemical calculations have been performed in a systematic way to explore the optoelectronic, charge transfer, and nonlinear optical (NLO) properties of different bis(dicyanomethylene) end-functionalized quinoidal oligothiophenes. The effect of different conformations (linking modes of thiophene rings) on conformational, optoelectronic, and NLO properties are studied from the best-performed dimer to octamer. The optical and NLO properties of all the selected systems (1-7) are calculated by means of density functional theory (DFT) methods. Among all the designed compounds, the largest linear isotropic (αiso) polarizability value of 603.1 × 10-24 esu is shown by compound 7 which is ∼12, ∼16, ∼9, ∼11, ∼10, and ∼4 times larger as compared to compounds 1-6, respectively. A relative investigation is performed considering the expansion in third-order NLO polarizability as a function of size and conformational modes. Among all the investigated systems, system 7 shows the highest value of static second hyperpolarizability ⟨γ⟩ with an amplitude of 7607 × 10-36 esu at the M06/6-311G** level of theory, which is ∼521, ∼505, ∼38, ∼884, ∼185, and ∼15 times more than that of compounds 1-6, respectively. The extensively larger ⟨γ⟩ amplitude of compound 7 with higher oscillator strength and lower transition energy indicates that NLO properties are remarkably dependent upon linking modes of thiophene rings and its chain length. Furthermore, to trace the origin of higher nonlinearities, TD-DFT calculations are also performed at the same TD-M06/6-311G** level of theory. Additionally, a comprehensive understanding of the effect of structure/property relationship on the NLO polarizabilities of these investigated quinoidal oligothiophenes is obtained through the inspection of Frontier molecular orbitals, the density of states (TDOS and PDOS), and molecular electrostatic potential diagrams including the transition density matrix. Hence, the current examination will not just feature the NLO capability of entitled compounds yet additionally incite the interest of experimentalists to adequately modify the structure of these oligothiophenes for efficient optical and NLO applications.
Fulltext Multigene phylogeny and morphological descriptions of five species of Agaricus sect. Minores from subtropical climate zones of Pakistan

Bashir H, Asif M, Ghafoor A, Niazi AR, Khalid AN, Parveen G, et al.

PLoS One, 2024;19(7):e0302222.
PMID: 38990811 DOI: 10.1371/journal.pone.0302222

The genus Agaricus includes more than 500 species mostly containing the edible and cultivated species worldwide. As part of the ongoing studies on the biodiversity of genus Agaricus in Pakistan, our objective was to focus on A. sect. Minores which is the largest section of the genus. In the first phylogenetic analyses based on the ITS region of the nuclear ribosomal DNA, our sample included specimens of 97 named species, 27 unnamed species, and 31 specimens (29 newly generated sequences in this study) from subtropical climate zones of Pakistan that likely belong to this section based on their morphology. The 31 specimens grouped into five distinct, well-supported clades corresponding to five species: A. glabriusculus already known from Pakistan and India, A. robustulus first recorded from Pakistan and briefly described here but already known from Bénin, Malaysia, China, and Thailand, and three possibly endemic new species described in detail A. badiosquamulosus sp. nov., A. dunensis sp. nov., and A. violaceopunctatus sp. nov. The sixth species currently known in Pakistan, including A. latiumbonatus also found in Thailand, were included in a multigene tree based on ITS, LSU, and Tef-1α sequence data. They all belong to a large pantropical paraphyletic group while most temperate species belong to a distinct clade, which includes about half of the species of the section. The current study aims to propose three novel species of genus Agaricus based on comprehensive morphological as well as molecular phylogenetic evidences from Pakistan.
Synthesis of acyl hydrazide derivatives of α-naphthalene acetic acid as COX-2 inhibitors: in vitro evaluation, molecular docking and DFT studies

Bibi A, Alam A, Fareed G, Ayaz M, Shah TA, Naz S, et al.

Future Med Chem, 2026 Apr;18(8):881-893.
PMID: 41808456 DOI: 10.1080/17568919.2026.2642677

AIMS: Cyclooxygenase-2 (COX-2) is a key enzyme in pain perception and inflammatory cascade that make it an attractive target to develop safer anti-inflammatory agents.
METHOD: In pursuit of potential anti-inflammatory agents, a new series based on α-naphthalene acetic acid has been synthesized through multi step reactions process. 1H-NMR and 13C-NMR spectroscopic techniques were used to confirm the structures of these derivatives.
RESULTS: These compounds have been assessed for their in vitro COX-2 inhibitory activity, among them, compounds (4, 5, 13, and 3) exhibited excellent activity with IC50 value ranging from (IC50 = 0.36 ± 0.22 µM) to (IC50 = 0.43 ± 0.60 µM), while compounds (12, 11, and 14) showed significant activity.
DISCUSSION: The molecular docking and density functional theory (DFT) analyses exposed that hydrazide derivatives based on α-naphthylene acetic acid displayed strong binding affinity for COX-2. Compound 13 revealed the highest binding energy of -9.771 kJ mol-1 and the lowest IC50 (0.43 µM) over π-π interactions and multiple hydrogen bonds. DFT study exposed that compound 13 influenced the highest softening and the smallest HOMO-LUMO energy gap, representing improved reactivity.
CONCLUSION: In general, the computational as well as experimental consequences specify that compound 13 is a potent COX-2 inhibitor.

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