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Despite their many advantages, issues remain unresolved over the variability in catalytic activities in supported gold nanoparticle (AuNP)-based catalysts, which requires precise characterization to unravel the presence of any fine features. Herein, upon analyzing the Au 4f core-level spin-orbit components in many as-synthesized AuNP-based catalysts, we observed that like deviations in the Au 4f7/2 binding energy positions, both the Au 4f7/2-to-Au 4f5/2 peak intensity and linewidth ratios varied largely from the standard statistical bulk reference values. These deviations were observed in all the as-synthesized supported AuNPs irrespective of different synthesis conditions, variations in size, shape or morphology of the gold nanoparticles, and different support materials. On the other hand, the spin-orbit-splitting values remained almost unchanged and did not show any appreciable deviations from the atomic or bulk standard gold values. These deviations could originate due to alterations in the electronic band structures in the supported AuNPs and might be present in other NP-based catalyst systems as well, which could be the subject of future research interest.

Metal phthalocyanines are considered to be prominent candidates for designing organic semiconductors. However, enhancing n‐type characteristics and air stability in these compounds have been the major challenges. Earlier studies on zinc phthalocyanines (ZnPc) reported enhancement in electron mobility due to fluorination. We present a theoretical study of the charge transfer and optical properties of functionalized zinc phthalocyanines (XZnPc, with X = F16, Cl16, Br16, I8, and (CN)8) within the framework of the density functional theory. Substitutions with electron‐withdrawing groups at the peripheral sites of ZnPc was found to lower both EHOMO and ELUMO in the compounds. Computed values of electron affinity (EA) > 3 eV in all XZnPcs indicated effective electron injection inferring enhanced n‐type characteristics and air stability in these compounds. However, cyanation ((CN)8), as compared to the other EWGs, is found to enhance the electron mobility more prominently in the compound. In addition, studied optical absorption spectra of all XZnPc compounds at different exchange‐correlation functionals such as B3LYP, PBE0, CAM‐B3LYP, wB97xD, M06, and M06‐2X exhibited Q‐band in visible region (∼600‐700 nm) and B‐band (Soret) in ultraviolet (∼300‐400 nm) region, and a few shows an N‐band below 300 nm. Upon functionalization, the B‐band and Q‐band maxima show bathochromic shift both in gas phase and dimethyl sulfoxide. All these optical absorptions were found to be prototypical in nature, and the spectra are assigned to π→π∗ character.

Poly(3-alkylthiophenes), P3[Alkyl]T, exhibit high mobility and efficiency of formation of polaronic chargecarriers generated by light absorption which gives them applications in field effect devices. Excited states ofπ -stacked dimers of tetra-thiophene oligomers (T4), infinite isolated polythiophene (PT) chains and P3[Alkyl]Tcrystals are modeled using configuration interaction singles (CIS) calculations. Excited states in cofacial T4dimers are mostly localized, Frenkel (FR) states except for two low energy CT exciton states which become theionization potential and electron affinity levels of T4 molecules at large dimer separation. The lowest excitedstates in infinite, isolated PT chains and P3[Alkyl]T crystals are intra-chain excitons where the electron and holeare localized on the same chain. The next lowest excited states are inter-chain, CT excitons in which electronand hole reside on neighboring chains. The former capture almost all optical oscillator strength and the lattermay be a route to efficient formation of polaronic charge carriers in P3[Alkyl]T systems. Changes in opticalabsorption energies of T4 dimers are explained as a function of molecular separation using CIS calculations withfour frontier orbitals in the active space. Shifts in optical absorption energy observed on going from isolatedchains to P3[Alkyl]T lamellar structures are already present in single-particle transition energies induced bydirect π - π interactions at short range. The electroabsorption spectrum of T4 dimers is calculated as a functionof dimer separation and states which are responsible for parallel and perpendicular components of the spectrumare identified.

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