Unveiling the influence of end-capped acceptors modification on photovoltaic properties of non-fullerene fused ring compounds: a DFT/TD-DFT study.

Herein, unique A-D-A configuration-based molecules (NBD1-NBD7) were designed from the reference compound (NBR) by utilizing the end-capped acceptor modification approach. Various electron-withdrawing units -F, -Cl, -CN, -NO2, -CF3, -HSO3, and -COOCH3, were incorporated into terminals of reference compound to designed NBD1-NBD7, respectively. A theoretical investigation employing the density functional theory (DFT) and time-dependent DFT (TD-DFT) was performed at B3LYP/6-311G(d,p) level. To reveal diverse opto-electronic and photovoltaic properties, the frontier molecular orbitals (FMOs), absorption maxima (λ max), density of states (DOS), exciton binding energy (E b), open-circuit voltage (V oc) and transition density matrix (TDM) analyses were executed at the same functional. Moreover, the global reactivity parameters (GRPs) were calculated using the HOMO-LUMO energy gaps from the FMOs. Significant results were obtained for the designed molecules (NBD1-NBD7) as compared to NBR. They showed lesser energy band gaps (2.024-2.157 eV) as compared to the NBR reference (2.147 eV). The tailored molecules also demonstrated bathochromic shifts in the chloroform (671.087-717.164 nm) and gas phases (623.251-653.404 nm) as compared to NBR compound (674.189 and 626.178 nm, respectively). From the photovoltaic perspectives, they showed promising results (2.024-2.157 V). Furthermore, the existence of intramolecular charge transfer (ICT) in the designed compounds was depicted via their DOS and TDM graphical plots. Among all the investigated molecules, NBD4 was disclosed as the excellent candidate for solar cell applications owing to its favorable properties such as the least band gap (2.024 eV), red-shifted λ max in the chloroform (717.164 nm) and gas (653.404 nm) phases as well as the minimal E b (0.126 eV). This is due to the presence of highly electronegative -NO2 unit at the terminal of electron withdrawing acceptor moiety, which leads to increased conjugation and enhanced the intramolecular charge transfer (ICT) rate. The obtained insights suggested that the designed molecules could be considered as promising materials for potential applications in the realm of OSCs.

Use of benzothiophene ring to improve the photovoltaic efficacy of cyanopyridinone-based organic chromophores: a DFT study.

The benzothiophene based chromophores (A1D1-A1D5) with A-π-A configuration were designed via end-capped tailoring with benzothiophene type acceptors using reference compound (A1R). Quantum chemical calculations were accomplished at M06/6-311G(d,p) level to probe optoelectronic and photophysical properties of designed chromophores. Therefore, frontier molecular orbitals (FMOs), binding energy (Eb), open circuit voltage (Voc), transition density matrix (TDM), density of state (DOS) and UV-Vis analyses of A1R and A1D1-A1D5 were accomplished. The designed compounds (A1D1-A1D5) exhibited absorption values in the visible region as 616.316-649.676 nm and 639.753-665.508 nm in gas and chloroform phase, respectively, comparing with reference chromophore. An efficient charge transference from HOMO towards LUMO was found in A1D1-A1D5 chromophores which was further supported by TDM and DOS analyses. Among all chromophores, A1D2 exhibited unique characteristics such as reduced band gap (2.354 eV), higher softness (σ = 0.424 eV), lower exciton binding energy (0.491 eV) and maximum value of open circuit voltage (Voc = 1.981 V). Consequently, A1D2 may be considered as potential candidate for the development of optoelectronic devices. These analyses revealed that the studied compounds exhibited promising findings. They may be utilized in the realm of organic solar cells.

Palladium(II)-catalyzed annulation of N-methoxy amides and arynes: computational mechanistic insights and substituents effects.

CONTEXT: The combined use of transition metal-catalyzed C-H activation with aryne annulation reactions has emerged as an important strategy in organic synthesis. In this study, the mechanisms of the palladium(II)-catalyzed annulation reaction of N-methoxy amides and arynes were computationally investigated by density functional theory. The role of methoxy amide as a directing group was elucidated through the calculation of three different pathways for the C-H activation step, showing that the pathway where amide nitrogen acts as a directing group is preferable. At the reductive elimination transition state, an unstable seven-membered ring is formed preventing the lactam formation. A substituent effect study based on an NBO analysis, Hammet, and using a More O'Ferall-Jenks plot indicates that the C-H activation step proceeds via an electrophilic concerted metalation-deprotonation (eCMD) mechanism. The results show that electron-withdrawing groups increase the activation barrier and contribute to an early Pd-C bond formation and a late C-H bond breaking when compared with electron-donating substituents. Our computational results are in agreement with the experimental data provided in the literature. METHODS: All calculations were performed using Gaussian 16 software. Geometry optimizations, frequency analyses at 393.15 K, and IRC calculations were conducted at the M06L/Def2-SVP level of theory. Corrected electronic energies, NBO charges, and Wiberg bond indexes were computed at the M06L/Def2-TZVP//M06L/Def2-SVP level of theory. Implicit solvent effects were considered in all calculations using the SMD model, with acetonitrile employed as the solvent.

Influence of acceptors on the optical nonlinearity of 5H-4-oxa-1,6,9-trithia-cyclopenta[b]-as-indacene-based chromophores with a push-pull assembly: a DFT approach.

Herein, a series of compounds (TPD1-TPD6) having a D-π-A architecture was quantum chemically designed via the structural modulation of TPR. Quantum chemical calculations were employed to gain a comprehensive insight into the structural and optoelectronic properties of the designed molecules at the M06/6-311G(d,p) level. Interestingly, all the designed chromophores displayed narrow energy gaps (2.123-1.788 eV) and wider absorption spectra (λmax = 833.619-719.709 nm) with a bathochromic shift in comparison to the reference compound (λmax = 749.602 nm and Egap = 3.177 eV). Further, Egap values were utilized to evaluate global reactivity parameters (GRPs), which indicate that all the chromophores expressed higher softness (σ = 0.134-0.559 eV-1) and lower hardness (η = 4.155-4.543 eV) values than the reference chromophore. Efficient charge transfer from donors towards acceptors was noted through FMOs, which was also supported by DOS and TDM analyses. Overall, the TPD3 derivative exhibited a remarkable reduction in the HOMO-LUMO band gap (1.788 eV) with a red shift as λmax = 833.619 nm. Furthermore, it exhibited prominent linear and non-linear characteristics such as µtotal = 24.1731 D, 〈α〉 = 2.89 × 10-22 esu, and ßtotal = 7.24 × 10-27 esu, among all derivatives. The above findings revealed that significant non-linear optical materials could be achieved through structural tailoring with studied efficient acceptors.

Exploration of linear and third-order nonlinear optical properties for donor-π-linker-acceptor chromophores derived from ATT-2 based non-fullerene molecule.

In the current study, seven non-fullerene compounds abbreviated as ATTD2-ATTD8 were designed through structural tailoring and their nonlinear optical (NLO) properties were reported. The objective of this study was to explore the potential for newly configured D-π-A type non-fullerene-based compounds. Quantum chemical methods were adopted and revealed the molecules as highly efficient materials with favorable NLO characteristics for use in optoelectronic devices. The M06 functional along with the 6-311G(d,p) basis set in chloroform solvent were utilized for the natural bonding orbital (NBO) analysis, absorption spectra and computational assessments of frontier molecular orbitals (FMOs), global reactivity descriptors (GRPs), transition density matrix (TDM) and nonlinear optical properties (NLO) for ATTR1 and ATTD2-ATTD8. The HOMO-LUMO energy gap was significantly reduced in all the designed moieties compared to the reference compound in the following decreasing order: ATTR1 > ATTD8 > ATTD4 > ATTD5 > ATTD2 > ATTD7 > ATTD6 > ATTD3. All of the designed molecules (ATTD2-ATTD8) showed good NLO response. Global reactivity parameters were found to be closely associated with the band gap between the HOMO and LUMO orbitals, and the compound with the smallest energy gap, ATTD3, exhibited a lower hardness value of 1.754 eV and higher softness value of 0.570 eV with outstanding NLO response. For the reference compound and ATTD2-ATTD8 derivatives, attributes like dipole moment (µtot), average polarizability 〈α〉, first hyperpolarizability (ßtot), and second hyperpolarizability γtot were calculated. Out of all the derivatives, ATTD3 revealed the highest amplitude with a ßtot of 8.23 × 10-27 esu, which was consistent with the reduced band gap (1.754 eV) and suggested it was the best possibility for NLO materials in the future.

Theoretical Perspective toward Designing of 5-Methylbenzo [1,2-b:3,4-b':6,5-b″] trithiophene-Based Nonlinear Optical Compounds with Extended Acceptors.

A series of benzotrithiophene-based compounds (DCTM1-DCTM6) having D1-π1-D2-π2-A configuration were designed using a reference molecule (DCTMR) via incorporating pyrrole rings (n = 1-5) as the π-spacer (π2). Quantum chemical calculations were performed to determine the impact of the pyrrole ring on the nonlinear optical (NLO) behavior of the above-mentioned chromophores. The optoelectronic properties of the compounds were determined at the MW1PW91/6-311G(d,p) functional. Among all of the derivatives, DCTM5 exhibited the least highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) band gap (Eg) 0.968 eV with a high softness of 0.562 eV-1, and hence possessed the highest polarizability. Interestingly, transition density matrix (TDM) findings demonstrated that DCTM5 with an effective diagonal charge transmission proportion at the acceptor group supports the frontier molecular orbital (FMO) results. Additionally, the exciton binding energy values for DCTM1-DCTM6 were found to be less than that for DCTMR and thus, the effective charge transfer was examined in the derivatives. All of the derivatives exhibited effective NLO outcomes with the highest magnitude of linear polarizability ⟨α⟩, and first (ßtot) and second (γtot) hyperpolarizabilities relative to the parent compound. Nevertheless, the highest ßtot and γtot were obtained for DTCM1 and DTCM6, 7.0440 × 10-27 and 22.260 × 10-34 esu, respectively. Hence, through this structural tailoring with a pyrrole spacer, effective NLO materials can be obtained for optoelectronic applications.

Influence of azacycle donor moieties on the photovoltaic properties of benzo[c][1,2,5]thiadiazole based organic systems: a DFT study.

Fullerene free organic chromophores are widely utilized to improve the efficacy of photovoltaic materials. Herein, we designed D-π-A-π-D form chromophores (TAZD1-TAZD5) via end-capped redistribution of donor moieties by keeping the same π-bridge and central acceptor unit for organic solar cells (OSCs). To analyze the photovoltaic characteristics of these derivatives, DFT estimations were accomplished at B3LYP/6-311 G (d,p) functional. Different investigations like frontier molecular orbital (FMO), absorption spectra (UV-Vis), density of states (DOS), binding energy (Eb), open circuit voltage (Voc), and transition density matrix (TDMs) were performed to examine the optical, photophysical and electronic characteristics of afore-mentioned chromophores. A suitable band gap (∆E = 2.723-2.659 eV) with larger bathochromic shift (λmax = 554.218-543.261 nm in acetonitrile) was seen in TAZD1-TAZD5. An effective charge transference from donor to acceptor via spacer was observed by FMO analysis which further supported by DOS and TDM. Further, lower binding energy values also supported the higher exciton dissociation and greater CT in TAZD1-TAZD5. Among all the designed chromophores, TAZD5 exhibited the narrowest Egap (2.659 eV) and maximum red-shifted absorption in solvent as well as gas phase i.e. 554.218 nm and 533.219 nm, respectively which perhaps as a result of the phenothiazine-based donor group (MPT). In a nutshell, all the tailored chromophores can be considered as efficient compounds for promising OSCs with a good Voc response, interestingly, TAZD5 is found to be excellent chromophores as compared to all these designed compounds.

Exploration of nonlinear optical enhancement in acceptor-π-donor indacenodithiophene based derivatives via structural variations: a DFT approach.

Herein, a series of indacenodithiophene-based derivatives (TNPD1-TNPD6) were designed having D-π-A architecture via end capped acceptor modulation of a reference molecule (TNPR) to investigate nonlinear optical (NLO) behavior. Quantum chemical calculations were accomplished to examine electronic, structural and optical properties utilizing a density functional theory (DFT) approach at M06 functional with 6-311G(d,p) basis set. For this, natural bond orbitals (NBOs), density of states (DOS), frontier molecular orbitals (FMOs), transition density matrix (TDM) and non-linear optical (NLO) analyses were performed for TNPR and TNPD1-TNPD6. The structural modifications revealed a significant electronic contribution in tuning the HOMOs and LUMOs of the derivatives with lowered energy gaps and wider absorption spectra. FMOs findings revealed that compound TNPD5 was found with the lowest energy gap (1.692 eV) and with the highest softness (0.591 eV-1) among the derivatives. Furthermore, a UV-Vis study also disclosed that maximum absorption (λmax = 852.242 nm) was exhibited by TNPD5 in chloroform solvent. All the derivatives exhibited significant NLO results; in particular, TNPD5 showed the highest first hyper-polarizability (ßtot = 4.653 × 10-27 esu) and second hyper-polarizability (γtot = 9.472 × 10-32 esu). These DFT findings revealed that the end-capped substituents play a key role in enhancing the NLO response of these push-pull chromophores and the studied derivatives can be utilized as efficient NLO materials.

Exploring Probenecid Derived 1,3,4-Oxadiazole-Phthalimide Hybrid as α-Amylase Inhibitor: Synthesis, Structural Investigation, and Molecular Modeling.

1,3,4-Oxadiazole moiety is a crucial pharmacophore in many biologically active compounds. In a typical synthesis, probenecid was subjected to a sequence of reactions to obtain a 1,3,4-oxadiazole-phthalimide hybrid (PESMP) in high yields. The NMR (1H and 13C) spectroscopic analysis initially confirmed the structure of PESMP. Further spectral aspects were validated based on a single-crystal XRD analysis. Experimental findings were confirmed afterwards by executing a Hirshfeld surface (HS) analysis and quantum mechanical computations. The HS analysis showed the role of the π⋯π stacking interactions in PESMP. PESMP was found to have a high stability and lower reactivity in terms of global reactivity parameters. α-Amylase inhibition studies revealed that the PESMP was a good inhibitor of α-amylase with an s value of 10.60 ± 0.16 µg/mL compared with that of standard acarbose (IC50 = 8.80 ± 0.21 µg/mL). Molecular docking was also utilized to reveal the binding pose and features of PESMP against the α-amylase enzyme. Via docking computations, the high potency of PESMP and acarbose towards the α-amylase enzyme was unveiled and confirmed by docking scores of -7.4 and -9.4 kcal/mol, respectively. These findings shine a new light on the potential of PESMP compounds as α-amylase inhibitors.

Enhancing the Photovoltaic Properties via Incorporation of Selenophene Units in Organic Chromophores with A2-π2-A1-π1-A2 Configuration: A DFT-Based Exploration.

Currently, polymer organic solar cells (POSCs) are widely utilized due to their significant application, such as low-cost power conversion efficiencies (PCEs). Therefore, we designed a series of photovoltaic materials (D1, D2, D3, D5 and D7) by the incorporation of selenophene units (n = 1-7) as π1-spacers by considering the importance of POSCs. Density functional theory (DFT) calculations were accomplished at MPW1PW91/6-311G (d, p) functional to explore the impact of additional selenophene units on the photovoltaic behavior of the above-mentioned compounds. A comparative analysis was conducted for designed compounds and reference compounds (D1). Reduction in energy gaps (∆E = 2.399 - 2.064 eV) with broader absorption wavelength (λmax = 655.480 - 728.376 nm) in chloroform along with larger charge transference rate was studied with the addition of selenophene units as compared to D1. A significantly higher exciton dissociation rate was studied as lower values of binding energy (Eb = 0.508 - 0.362 eV) were noted in derivatives than in the reference (Eb = 0.526 eV). Moreover, transition density matrix (TDM) and density of state (DOS) data also supported the efficient charge transition origination from HOMOs to LUMOs. Open circuit voltage (Voc) was also calculated for all the aforesaid compounds to check the efficiency, and significant results were seen (1.633-1.549 V). All the analyses supported our compounds as efficient POSCs materials with significant efficacy. These compounds might encourage the experimental researchers to synthesize them due to proficient photovoltaic materials.

A comprehensive benchmark investigation of quantum chemical methods for carbocations.

The application of various density functional approximations (DFAs) and an emphasis on popular methods without any consensus have prevailed in computational studies dedicated to carbocations. More importantly, an extensive and rigorous benchmark investigation on density functionals for the class is still lacking. To close this gap, we present a comprehensive benchmark study of quantum chemical methods on a series of classical and nonclassical carbocations, the CARBO33 dataset. We evaluate a total of 107 DFT methods from all rungs giving particular attention to double hybrid density functionals as the potential of the class has been largely undermined in the context of carbocations. To support our findings, DLPNO-CCSD(T) at the complete basis set (CBS) limit and W1-F12 are used as reference methods. Our results indicate that the composite CBS-QB3 method performs poorly and should not be adopted for target energies. Oftentimes, the tested DFAs of a lower rung perform better than several DFAs in a higher rung of Perdew's "Jacob's ladder". Nonetheless, double hybrids DSD-PBEP86-NL and ωB97X-2-D3(BJ) stand out by showing the overall best performance. Among the hybrids evaluated, about half of them show mean absolute deviation (MAD) below 1.1 kcal mol-1, including the popular hybrids M06-2X and mPW1PW91. In this family, MN15-D3(BJ) performs particularly well (MAD = 0.77 kcal mol-1) displaying reliable results across various tests. Highly popular B3LYP exhibited one of the worst performances (MAD = 4.74 kcal mol-1), and we do not recommend its application to carbocations. We also assess the 24 general-purpose basis sets of single- up to quadruple-ζ quality. The best compromise between accuracy and computational cost is achieved with cc-pVTZ followed by def2-TZVP. Computations on larger structures of general interest, including terpene carbocations, are also presented for selected DFT methods confirming general trends in the results.

Exploration of the interesting photovoltaic behavior of the fused benzothiophene dioxide moiety as a core donor with modification in acceptors for high-efficacy organic solar cells.

Non-fullerene-based chromophores with end-capped acceptor modification used in organic solar cells (OSCs) have proven to offer improved performance. Therefore, eight unique benzothiophene-based molecules (D2-D9) were designed by the end-capped acceptor manipulation of a reference molecule (R1). Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations at the B3LYP level were performed to investigate various parameters such as the optical properties, frontier molecular orbitals (FMOs), transition density matrix (TDM), binding energy, density of states (DOS), open-circuit voltage (V oc), and reorganization energies of electrons (λ e) and holes (λ h), to better understand the optoelectronic properties of the newly designed compounds. All the derivatives had broader absorption spectra of 737.562-700.555 nm with a reduced energy gap of 2.132-1.851 eV compared to those of the reference (719.082 nm), except for D8 and D9. A comparable value of V oc and lower reorganization energies were found in the derivatives compared to those of R1. Within the studied compounds, D3 was predicted to be a good optoelectronic material for environmentally friendly organic solar cells (EFOSCs) because of its superior optoelectronic capabilities, low-energy band gap (1.851 eV), highest λ max values of 794.516 and 744.784 nm in chloroform and the gas phase, respectively, and lowest transition energy (1.561 eV) than those of the reference and the other derivatives. Subsequently, end-capped acceptor modification was proven to be an effective method to achieve desired optoelectronic characteristics.

First theoretical framework for highly efficient photovoltaic parameters by structural modification with benzothiophene-incorporated acceptors in dithiophene based chromophores.

Now a days, researchers are constantly doing efforts to upgrade the performance of solar based devices with the aim of increasing the role of photovoltaic materials in modern hi-tech optoelectronic applications. Realizing the recent energy conditions across the globe, research is diverted from fullerene to non-fullerene electron acceptor moieties in this era, considering their remarkable contribution in organic solar cells (OSCs). Therefore, we designed seven novel non-fullerene fused ring electron acceptor chromophores (MD2-MD8) from DOC2C6-2F by structural tailoring with different acceptors at end-capped units. DFT study was performed at B3LYP functional to discover the opto-electronic characteristics of the newly tailored chromophores. Various analysis such as frontier molecular orbitals (FMOs), transition density matrix (TDM), density of states (DOS), binding energy (Eb), reorganization energy, open circuit voltage (Voc) was carried out to comprehend the photovoltaic response of MD2-MD8. Decrease in band gaps (1.940-1.571 eV) with wider absorption spectrum (725.690-939.844 nm in chloroform) along with greater charge transfer rate from HOMO towards LUMO were examined in derivatives as compared to MR1 (Egap = 1.976 eV, λmax = 738.221 nm) except MD7. Further, in all derivatives, smaller values of Eb (0.252-0.279 eV) were examined than that of reference (0.296 eV). These lower binding energy values of MD2-MD8 indicated the higher rate of excitation dissociation with lager charger transfer rate than MR1, which further supported by DOS and TDM analyses. Additionally, least reorganization energy in the aforesaid compounds for hole with electron was also inspected. Moreover, Voc a good photovoltaic response was noted for all studied compounds which indicated that these compounds are suitable to synthesize OSCs in future.

Understanding the reaction mechanism of the CO2 and cyclohexene oxide copolymerization catalyzed by zinc(II) and magnesium(II) catalysts: a DFT approach.

The reaction mechanisms of carbon dioxide and cyclohexene oxide copolymerization catalyzed by four different zinc(II)-magnesium(II) (labeled as M1-M2) catalysts were computationally studied using density functional theory at the BP86-D3(BJ)/def2-TZVP/SMD//BP86-D3(BJ)/def2-SVP/SMD level of theory. The results showed that the most effective catalyst was the ZnMg system, in which poly(cyclohexene carbonate) was the preferred product, followed by the side product cis-cyclohexene carbonate. The QTAIM, NCI and ELF analysis performed to understand the role of metals in the reaction showed that ligands and substrates interact more strongly with zinc(II) centers compared to magnesium(II) centers. Furthermore, the Zn-I interaction at the M1 position was stronger than the Mg-I interaction at the same position. All these results indicate a synergism between the metals Zn and Mg, which makes Zn(II)Mg(II) the best combination for the reaction.

Enriching NLO efficacy via designing non-fullerene molecules with the modification of acceptor moieties into ICIF2F: an emerging theoretical approach.

Non-fullerene (NF)-based compounds have attracted much attention as compared to fullerene-based materials because of their promising optoelectronic properties, lower synthetic cost and greater stability. Usually, the end-capped groups have a promising impact in magnifying the nonlinear optical (NLO) characteristics in the non-fullerene molecules. Based on this, a series of new NLO active non-fullerene molecules (NFAD2-NFAD6) have been established. The non-fullerene molecules (NFAD2-NFAD6) were designed by end-capped modification in acceptor moieties of the reference (NFAR1), while donor and π-bridge moieties were kept the same in the entire series. Quantum chemistry-based calculations at the M06/6-311G(d,p) level were done to determine the NLO characteristics and for other supportive analyses. The acceptor and donor moieties were utilized at the opposite terminals of NFAD2-NFAD6, which proved to be an effective approach in tuning the FMO band gap. Overall the results of natural bond orbital (NBO), density of state (DOS) and transition density matrices (TDMs) analyses supported the NLO properties of the designed compounds. Among all the studied compounds, NFAD4 was proven to be the most suitable candidate due to its promising NLO properties, well supported by a lower bandgap of 1.519 eV and a maximum absorption wavelength of 999.550 nm. Therefore, NFAD4 was reported with greater amplitude of dipole polarizability (10.429 e.s.u), average polarizability (2.953 × 10-22 e.s.u), first hyperpolarizability (13.16 × 10-27 e.s.u.) and second hyperpolarizability (2.150 × 10-31 e.s.u.) than other derivatives and NFAR1. Subsequently, the present study depicted the significance of utilizing different non-fullerene (NF)-based acceptor moieties to achieve the promising NLO material. This computational study may lead towards new plausible pathways for researchers to design potent NLO substances for impending hi-tech applications.

Influence of Peripheral Modification of Electron Acceptors in Nonfullerene (O-IDTBR1)-Based Derivatives on Nonlinear Optical Response: DFT/TDDFT Study.

Fullerene-based organic compounds have been reported as useful materials with some limitations; nonetheless, fullerene-free compounds are primarily considered to be the most substantial materials for the development of modern technology. Therefore, in this study, a series of compounds (NFBC2-NFBC7) having an A-π-D architecture were designed for the first time from a synthesized nonfullerene (O-IDTBR) compound by changing different acceptor groups. The synthesized nonfullerene (O-IDTBR1) compound and its designed derivatives were optimized with frequency analyses at the M06/6-311G(d,p) level. These optimized structures were further characterized by different quantum chemical approaches. The study required that the designed compounds possess a low energy gap in comparison to that of O-IDTBR1 (2.385 eV). Moreover, density of state (DOS) calculations supported the FMO analysis and displayed charge transfers from the HOMO to the LUMO in an effective manner. The λmax values of the investigated chromophores were observed to be greater than that of the reference compound. Amazingly, the highest amplitude of linear polarizability ⟨α⟩ and first (ßtot) and second hyperpolarizability values were achieved by NFBC6 at 1956.433, 2155888.013, and 7.868 × 108 au, respectively, among all other derivatives. Effective NLO findings revealed that nonfullerene-based derivatives may contribute significantly to NLO technology.

Donor moieties with D-π-a framing modulated electronic and nonlinear optical properties for non-fullerene-based chromophores.

Herein, a series of non-fullerene-based substantial chromophores (FHD1-FHD6) with a D-π-A framework was designed from a synthesized non-fullerene compound (FH) via structural tailoring with various donor moieties. The FH and its designed derivatives were optimized with frequency analysis at the M06/6-311G (d,p) level to confirm their true minima on potential energy surfaces. These optimized geometries were utilized to perform further analyses, such as absorption, natural bonding orbital (NBO), frontier molecular orbital (FMO), and nonlinear orbital (NLO) analyses at the aforesaid level. Quantum chemical study revealed that all the designed chromophores exhibited a lower band gap than that of the parent molecule with the exception of FHD3. Furthermore, density of states (DOS) analysis supported the findings from the FMO study, and this agreement revealed that the efficient charge was transferred from the HOMO to the LUMO. The NBO investigations disclosed that all the compounds comprised donor moieties with positive charges and acceptors having negative charges. Interestingly, π-conjugated linkers were also found with positive charges, showing an effective donating property. These NBO findings explicated that FHD1-FHD6 exhibited an efficient push-pull mechanism. The λ max values of the designed chromophores were observed to be greater than the reference compound. The average polarizability 〈α〉, first hyperpolarizability (ß tot), and second hyperpolarizability 〈γ〉 values of FHD2 were found to be 2.170 × 10-22, 3.150 × 10-27, and 4.275 × 10-32 esu, respectively, while all the other derivatives had been reported in the relevant range. Efficient NLO data revealed that FH-based derivatives may contribute significantly toward NLO technology.

Do Double-Hybrid Exchange-Correlation Functionals Provide Accurate Chemical Shifts? A Benchmark Assessment for Proton NMR.

A benchmark density functional theory (DFT) study of 1H NMR chemical shifts for data sets comprising 200 chemical shifts, including complex natural products, has been carried out to assess the performance of DFT methods. Two new benchmark data sets, NMRH33 and NMRH148, have been established. The meta-GGA revTPSS performs remarkably well against the NMRH33 benchmark set (mean absolute deviation (MAD), 0.10 ppm; maximum deviation (max), 0.26 ppm) with the smallest MAD of all evaluated functionals. The best-performing double-hybrid density functional (DHDF), revDSD-BLYP (MAD, 0.16 ppm; max, 0.35 ppm), performs similarly to hybrid-GGA methods (e.g., mPW1PW91/6-311G(d) (MAD, 0.15 ppm; max, 0.36 ppm)), but at a considerably higher computational cost. The results indicate that currently available double-hybrid DFT methods offer no benefit over GGA (including hybrid and meta) functionals in the calculation of 1H NMR chemical shifts.

Structural modulation of π-conjugated linkers in D-π-A dyes based on triphenylamine dicyanovinylene framework to explore the NLO properties.

A donor-π-acceptor type series of Triphenylamine-dicyanovinylene-based chromophores (DPMN1-DPMN11) was designed theoretically by the structural tailoring of π-linkers of experimentally synthesized molecules DTTh and DTTz to exploit changes in the optical properties and their nonlinear optical materials (NLO) behaviour. Density functional theory (DFT) computations were employed to understand the electronic structures, absorption spectra, charge transfer phenomena and the influence of these structural modifications on NLO properties. Interestingly, all investigated chromophores exhibited lower band gap (2.22-2.60 eV) with broad absorption spectra in the visible region, reflecting the remarkable NLO response. Furthermore, natural bond orbital (NBO) findings revealed a strong push-pull mechanism in DPMN1-DPMN11 as donor and π-conjugates exhibited positive, while all acceptors showed negative values. Examination of electronic transitions from donor to acceptor moieties via π-conjugated linkers revealed greater linear (〈α〉 = 526.536-641.756 a.u.) and nonlinear (ß tot = 51 313.8-314 412.661 a.u.) response. It was noted that the chromophores containing imidazole in the second p-linker expressed greater hyperpolarizability when compared with the ones containing pyrrole. This study reveals that by controlling the type of π-spacers, interesting metal-free NLO materials can be designed, which can be valuable for the hi-tech NLO applications.

DFT study of H2 adsorption at a Cu-SSZ-13 zeolite: a cluster approach.

In this work the H2 adsorption at a Cu(i)-SSZ-13 exchanged zeolite was theoretically investigated. A systematic cluster approach was used and different density functionals (B3LYP, B3LYP-D3(BJ), M06L, PBE, PBE-D3(BJ) and ωB97XD) and a def2-SVP basis set were benchmarked. In order to select the best approach to the H2 adsorption over a Cu(i)-SSZ-13 cluster with 78 atoms (16 T-sites), two main tasks were performed: (1) a comparison between theoretical and experimental structures and (2) a comparison between theoretical and experimental adsorption enthalpies. By employing the most suitable functional - the ωB97X-D - the H2 interaction with the zeolite structure was studied by means of NBO, NCI, AIM and DLPNO-CCSD(T)/LED analyses.