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The present study evaluates the CO2 adsorption capacity of functionalized rutile TiO2(110), using the density functional theory and ab initio molecular dynamics simulations. The defect-free TiO2 surface is functionalized (f-TiO2) with alkanolamines (AKAs), namely, monoethanolamine (MEA), 3-aminopropanol (3AP), and amino acids (AAs) glycine (GLY) and β-alanine (β-ALA). These functionalized adsorbents attain stability through bifunctional/bidentate binding of weakly acidic OH/COOH groups to TiO2 surface. The AKAs bind parallel to the surface, whereas the AAs bind perpendicular to the TiO2 surface, exhibiting several binding sites favorable for multiple, cooperative noncovalent interactions with CO2. The nature and strength of these interactions are evaluated in terms of binding energies, vibrational frequencies, quantum theory of atoms in molecules (QTAIM) approach, and charge-transfer analysis. The subtle yet substantial interactions of CO2 with f-TiO2 will lead to physisorption and diffusion through pores...

The constant increase in greenhouse gases, namely CH4, N2O, and CO2, in the atmosphere is the major cause of the global warming phenomenon. An economical and sustainable CO2 capture technology will enable the industries to use fossil-based fuel while restraining the CO2 emissions into the atmosphere. Among different methods reported for the removal of CO2 from point resources, the CO2 capture by using solid sorbents is considered a promising technology as they are less corrosive, less toxic, and exhibit high CO2 capture efficiency compared to conventional liquid solvents. Further, solid adsorbents demonstrated the ability to substantially reduce the capital and operating costs for CO2 capture process. However, the lack of mechanical and thermal stabilities of a wide range of solid adsorbents reported for CO2 capture till today is a major impediment in order to scale up the materials and demonstrate operating conditions at the plant. Carbonaceous and silica-based materials are some of the suitable alternative sorbents owing to their abundance, low cost, and stability at high temperatures. However, low working capacity of these materials is a major drawback for large-scale production. In order to obtain improved performances of these materials toward CO2 capture, one of the strategies adopted is to functionalize solid adsorbents with different structural moieties that selectively bind to CO2 with optimal adsorption energies. This chapter presents a review of different functionalized sorbents that have shown improved performance than the parent materials. The main focus of this chapter is to summarize the performances of reported functionalized solid adsorbents and to find the challenges and solutions for the future directions.

Current pandemics propelled research efforts in unprecedented fashion, primarily triggering computational efforts towards new vaccine and drug development as well as drug repurposing. There is an urgent need to design novel drugs with targeted biological activity and minimum adverse reactions that may be useful to manage viral outbreaks. Hence an attempt has been made to develop Machine Learning based predictive models that can be used to assess whether a compound has the potency to be antiviral or not. To this end, a set of 2358 antiviral compounds were compiled from the CAS COVID-19 antiviral SAR dataset whose activity was reported based on IC50 value. A total 1157 two-dimensional molecular descriptors were computed among which, the most highly correlated descriptors were selected using Tree-based, Correlation-based and Mutual information-based feature selection methods. Seven Machine Learning algorithms i. e., Random Forest, XGBoost, Support Vector Machine, KNN, Decision Tree, MLP Classifier and Logistic Regression were benchmarked. The best performance was achieved by the models developed using Random Forest and XGBoost algorithms in all the feature selection methods. The maximum predictive accuracy of both these models was 88 % with internal validation. Whereas, with an external dataset, a maximum accuracy of 93.10 % for XGBoost and 100 % for Random Forest based model was achievable. Furthermore, the study demonstrated scaffold analysis of the molecules as a pragmatic approach to explore the importance of structurally diverse compounds in data driven studies.

Herein, for the first time we report the synthesis of a series of compositionally tunable Zr-doped novel KNb(Zr)O3 perovskites using green and facile methodology and their superior photocatalytic activities toward photoinduced hydrogen production and dye degradation. The substitutional doping of Zr(IV) in place of Nb(V) leads to a decrease in the electronic band gap by inclusion of a new acceptor level near the valence band. The results on the optimally doped perovskite for the photocatalytic hydrogen evolution reaction reveal that the 20 mol % Zr-doped KNb(Zr)O3 is 13 times more efficient as compared to the pristine KNbO3 in terms of rate of H2 evolution. The same nanocomposite is shown to exhibit 12-fold greater photocatalytic efficiency for degradation of Rhodamine B (RhB) (up to 83% after 210 min) than pure KNbO3. Density functional theory calculations are carried out to understand the Zr doping effect on the electronic structure as well as the surface hydrogen evolution reaction. Overall, an optimize...

We have designed and synthesized two new ligands based on N-heteroleptic/phenyl carbene (NH-phenyl C) i.e., 1-benzyl-2-(3,5-bis(trifluoromethyl)phenyl)-1H-benzo[d]imidazole (L1) and 3-(1-benzyl-1H-benzol-2-yl)-10-hexyl-10-H-phenothiazene (L2), used as ancillary ligands to heteroleptic Ru(II) complexes for dye-sensitized solar cells. Both NCS groups of the N719 sensitizer are replaced with L1 (TC-1) and L2 (TC-3) to obtain cyclometalated Ru(II) complexes and one of 4,4′-dicarboxylato-2,2′-bipyridine (dcbpy) with L1 to obtain a heteroleptic Ru(II) complex (TC-2). The presence of two trifluoromethyl groups of the L1 ligand stabilizes the HOMO level of Ru(II) complexes and the presence of a phenothiazine moiety of the L2 ligand alters the absorption properties of the TC-3 complex. Both the ligands and the heteroleptic Ru(II) complexes are characterized by elemental analyses, ESI-MS, 1H NMR, absorption and emission spectroscopy as well as electrochemical methods. The absorption spectra of TC-1 and TC-3 are blue shifted, when compared to the standard N719 sensitizer. The assessment of these newly designed cyclometalated and heteroleptic Ru(II) complexes has revealed that TC-2 exhibits an efficiency of 7.63%, whereas TC-1 has an efficiency of 6.39% using an I−/I3− redox couple. DFT and nanosecond transient absorption kinetic studies have been adopted to understand the low efficiency of the TC-3 complex.

Zeolitic imidazolate frameworks (ZIFs) represent the class of metal–organic frameworks (MOFs) that possess high porosity, large surface area, exceptional thermal, and chemical stability. Because of these properties, ZIFs are being employed extensively in gas separation and selective CO2 adsorption. We have chosen the structural modification approach to enhance the CO2 binding ability of various imidazolate (Im) linkers of ZIFs by systematically varying the substituents at 2, 4, and 5 positions of Im ring with CH3, Cl, CN, OH, NH2, and NO2 functional groups. Density functional theory (DFT) calculations have been employed to identify and quantify the CO2 binding ability of various adsorption sites present in 137 Im linkers. The study demonstrates that the Im linkers with asymmetrical substitution, viz. NO2/OH, CN/OH, and Cl/OH combinations are highly promising linkers of ZIFs for efficient CO2 adsorption. The QTAIM analysis characterizes these interactions as noncovalent interactions which are stabilized by...

First principles calculations based on density functional theory (DFT) have been performed to design a new set of donor-corrole-bridge-acceptor type systems based on the gallium corroles for dye-sensitized solar cell applications. The design strategy for these systems is based on the benchmark studies done on the experimentally tested aluminum, gallium, and tin metallocorroles. Unfortunately, corrole analogues display poor light to current conversion efficiencies in spite of their desirable photophysical properties. Thus, improving the efficiency of corrole analogues has become a major challenge and ways to identify solutions to this is of outstanding fundamental importance. This study shows the lack of charge directionality toward anchoring group as plausible reason for the poor efficiencies of reported corrole systems, which enabled us to fine-tune the electronic and optical properties of new D-π-A type systems, COR1-COR4. The molecular geometries, electronic structure, and binding orientation of these systems on TiO2 surface were investigated using DFT, TD-DFT, and PBC methods. When compared with the reported corroles, COR1-COR4 have a smaller band gaps, red-shifted absorption spectra with higher extinction coefficients (105 M−1 cm−1) and improved nonlinear optical properties. Importantly, results revealed that these dyes bind with two-arm mode to TiO2 surface and the density of states of the dye@TiO2 elucidate strong coupling between the dyes and TiO2 surface. We anticipate that the unique photophysical properties of these sensitizers will trigger the experimental efforts to yield a new generation of sensitizers based on corrole macrocyle. © 2015 Wiley Periodicals, Inc.

A joint experimental and computational study on a series of four β-carboxy-corroles, both in free-base and in copper complexes form, is presented. The main goal of the work is to understand by means of high-level DFT and TDDFT calculations the reasons for the low photovoltaic performances obtained for these dyes when employed in dye-sensitized solar cells. We also report a comparison between the unsubstituted 5-10-15,triphenyl-corrole and his 3-carboxylated analog, in order to investigate the effect of the carboxylic acid on the geometrical, electrochemical and optical properties of these sensitizers. By modeling the adsorption of the investigated dyes on an extended TiO 2 nanocluster and by analyzing the Density of State composition of the dye@TiO 2 systems, we basically find an unfavorable dye/semiconductor energy level alignment for the electron injection process, possibly accounting for the poor photovoltaic performances of these corroles compounds.

Molecular triads based on bis(porphyrin)-anthraquinone having azomethine bridge at the pyrrole-β position have been designed and synthesized. Both free-base AQ-(H2)2 and zinc AQ-(Zn)2 triads are characterized by elemental analysis, MALDI-MS, (1)H NMR, UV-visible, and fluorescence spectroscopy (steady-state and time-resolved) as well as electrochemical method. The absorption spectra of both Soret and Q-bands of the triads are red-shifted by 12-20 nm with respect to their monomer units. The study supported by theoretical calculations manifests that there exists a negligible electronic communication in the ground state between the donor porphyrin and acceptor anthraquinone of these triads. However, interestingly, both the triads exhibit significant fluorescence emission quenching (51-92%) of the porphyrin emission compared to their monomeric units. The emission quenching is attributed to the excited-state intramolecular photoinduced electron transfer from porphyrins to anthraquinone. The electron-transfer rates (kET) of these triads are found in the range 1.0 × 10(8) to 7.7 × 10(9) s(-1) and are found to be solvent dependent.

The current study reports the one-step synthesis and gelation properties of cyclohexane-based bis(acyl-semicarbazide) gelators with an additional -NH group incorporated into urea moieties and carrying hydrophobic chains of varying length (C8-C18). The gels exhibited thermoreversibility and could be tuned in the presence of anions at different concentrations in addition their the ultrasound-responsive nature, thus making them multi-stimuli-responsive. The combined experimental and computational study on these gels reveals that the balance between two noncovalent interactions, viz., hydrogen bonding between the amide groups in acyl-semicarbazide moieties and van der Waals forces between long hydrocarbon tails, is found to be the determining factor in the process of organogelation. A systematic increase in alkyl chain length leads to equilibrium between these two types of noncovalent forces that is manifested in the spectral and thermal properties of the gels. The H-bonding interactions dominated up to a certain chain length, and further increases in the alkyl chain length led to increased van der Waals interactions as observed by IR, XRD, and thermal studies. Computational calculations were carried out on dimer structures of C8-C18 to understand the variation in noncovalent forces responsible for aggregate formation in the gel state as a function of the alkyl chain length. The results indicate that both intermolecular and intramolecular hydrogen bonding stabilize the aggregate structures. Supramolecular aggregation in the gel state led to the viscoelastic nature of the gels, and the addition of anions led to the disruption of self-assembly, which was studied by rheology.

C3 symmetric chiral trimethylsumanene was enantioselectively synthesized through Pd-catalyzed syn-selective cyclotrimerization of an enantiomerically pure iodonorbornenone, ring-opening/closing ole...

Two new ruthenium(II) mixed ligand terpyridine complexes, “Ru(Htcterpy)(NCS)(L1) (N(C4H9)4), mLBD1” and Ru(Htcterpy)(NCS)(L2)(N(C4H9)4), mLBD2 were synthesized and fully characterized by UV-Vis, emission, cyclic voltammogram, and other spectroscopic means, and the structures of the compounds are confirmed by 1H-NMR, ESI-MASS, and FT-IR spectroscopes. The influence of the substitution of L1 and L2 on solar-to-electrical energy conversion efficiency (η) of dye-sensitized solar cells (DSSCs) was evaluated relative to reference black dye. The dyes showed molar extinction coefficients of 17600 M−1 cm−1 for mLBD1 and 21300 M−1 cm−1 for mLBD2 both at λ maximum of 512 nm, while black dye has shown 8660 M−1 cm−1 at λ maximum of 615 nm. The monochromatic incident photon-to-collected electron conversion efficiencies of 60.71% and 75.89% were obtained for mLBD1 and mLBD2 dyes, respectively. The energy conversion efficiencies of mLBD1 and mLBD2 dyes are 3.15% ( mA/cm2, mV, ) and 3.36% ( mA/cm2, mV, ), respectively, measured at the AM1.5G conditions, the reference black dye-sensitized solar cell, fabricated and evaluated under identical conditions exhibited η-value of 2.69% ( mA/cm2, mV, ).

New polypyridyl ruthenium(II) complexes "cis-Ru(4,4'-dimesity1-2,2'-bipyridine) (Ln) (NCS)(2) H102" and "cis-Ru(4,4'-bis(2,3,6-tri-isopropylphenyl)-2,2'-bipyridine) (Ln) (NCS)(2) H105", where Ln = 4,4'-dicarboxylic acid-2,2'-bipyridine; were synthesized and successfully applied to sensitization of nano-crystalline TiO2 based solar cells (DSSCs). The DSSCs of H102 and H105 fabricated from 0.16 cm(2) TiO2 electrodes exhibited broader comparable photocurrent action spectra with almost identical solar-to-electrical energy conversion efficiency (II) as compared to N719 sensitizer. The incident photon-to-current conversion efficiency (IPCE) values of 98% and 95% were obtained for H102 and H105 sensitizers respectively. Under 1 sun condition, eta-values of 8.39% (short-circuit photocurrent (J(SC))= 16.4 mA/cm(2), open-circuit photo voltage (V-OC) = 692 mV, fill factor = 0.734), 8.76% (J(SC) = 16.3 mA/cm(2), V-OC = 735 mV, fill factor = 0.734) and 9.12% (J(SC) = 16.1 mA/cm(2), V-OC = 745 mV, fill factor = 0.753) were obtained for H102, H105 and N719 sensitizers respectively. (C) 2011 Elsevier B.V. All rights reserved.

Theoretical investigations have been carried out at B3LYP/6-311++G** level of theory to study the binding interaction of various metal ions, Li+, Na+ and K+ with dehydroannulene systems. The present study reveals that alkali metal ions bind strongly to dehydroannulenes and the passage through the central cavity is controlled by the size of metal ion and dimension of dehydroannulene cavity.

Theoretical calculations by means of density functional theory (DFT) at the B3LYP/6-31G(d) level have been performed to elucidate the antioxidant mechanism of 1,3-dihydro-1-methyl-2H-imidazole-2-selenol (MSeI) at the molecular level. The present detailed computational study of individual steps of the mechanism provides energetics and structures of all the intermediates and transition states. DFT results suggest a highly synchronous stepwise mechanism wherein the nucleophilic attack of thiol at the sulfur atom in selenyl sulfide (TS VII–VIII) is found to be the rate-determining step, which initiates the catalytic regeneration of selenol. The current computational studies are in excellent agreement with the mechanism proposed earlier.

B3LYP/6-311 G** calculations were performed systematically on 1,2( syn ) and 1,3 ( anti ) tautomeric forms of oxa- and thia- core-modified porphyrin isomers,which resulted in a total of 86 structures. The structural and energetic variation in allthe isomers were analyzed. In corrphycene, hemiporphycene and porphycene the Zforms are more stable compared to the corresponding E forms in both the anti and syn oxa- and thiaporphyrin isomers. In contrast, in the syn isomeric forms of [3.0.1.0],[3.1.0.0] and [4.0.0.0] oxaporphyrins and in both syn and anti forms of thiaporphyrinisomers, Z forms are less stable. The HOMO and LUMO values are both negative andvaried in a narrow zone, indicating no dramatic effect on the position of heteroatomsubstitution on the redox properties. The effect of geometric constraints due to thealteration of meso-bridge length and the hetero atom disposition in the porphyrin coreon the relative stabilities of the isomers is analyzed. © 2006 Wiley Periodicals, Inc. Int JQuantum Chem 107: 134–151, 2007

Diastereomeric conduramine derivatives, i.e., (1R,2S,3R/S,6S)-6-(N-carbomethoxyamino) 1,2-O-isopropylidenecyclohex-4-ene-1,2,3-triol (1 and 2) and their O-acetyl derivatives (3 and 4), were studied using gas chromatography (GC) with electron ionization (EI) and chemical ionization (CI). The EI mass spectra of diastereomeric pairs show consistent differences in the relative abundances of characteristic ions. The EI fragmentation patterns are based on precursor/product ion spectra, high-resolution mass spectrometry (HRMS) and deuterium labelling. The CI spectra show differences from the EI spectra, and the isobutane/CI spectra are much simpler than the methane/CI spectra. The differences shown in the CI spectra are similar to those shown in the product ion spectra of [M+H]+ ions generated under electrospray ionization (ESI) conditions. Theoretical calculations are performed to understand the observed differences. The differences in the relative stabilities of molecular ions, or protonated molecules at different sites, can explain the observed differences in the spectra. Copyright © 2007 John Wiley & Sons, Ltd.

We have designed and synthesized heteroleptic Ru(II) complexes with a pyridine-benzimidazole ligand (PYBI) for dye-sensitized solar cell (DSSC) applications. The PYBI ligand has major advantages by having the flexibility to introduce appropriate substituents at the four readily available positions through molecular engineering (Chart 1) compared to other ancillary bipyridyl-based ligands. We have substituted position A of the PYBI ligand with either electron-releasing triphenylamine (1) or pyrene (2). We have also introduced 2-hexylthiophene at position A and 3,5-di tert-butyl phenyl group at position B of the PYBI ligand (3). All three heteroleptic Ru(II) complexes have been characterized by mass spectrometry, 1H NMR, and absorption and emission spectroscopies as well as electrochemical methods. The absorption spectrum of complex 3 is red-shifted and the emission spectrum is blue-shifted, when compared to the standard N719 sensitizer. Testing of these newly designed heteroleptic Ru(II) sensitizers has revealed that complex 3 exhibits an efficiency of 7.88% using an I−/I3− redox electrolyte. Experimental observations corroborated by computational calculations have elucidated the high efficiency of complex 3, primarily due to the fact that the substituents at position A are more influential than those at position of B of the PYBI ligand.

The cation binding strength of calix[4]pyrroles in the gas phase has been evaluated by computational studies and further substantiated by ESI mass spectrometry experiments. The DFT optimized geometries of [CP + X](+) complexes are found to be stable in a 1,3-alternate conformation through cation-π interactions and interestingly CPs are found to be better cation receptor than calix[4]arenes. The binding energy values of [CP + X](+) complexes computed at B2PLYP/TZVP//M05-2X/TZVP follows the binding order, Li(+)Na(+)K(+)Rb(+)Cs(+). The diameter of Li(+) matches very well with the cavity size of CP and thus is optimally disposed to interact simultaneously with all four pyrrole rings through multiple cation-π interactions. However, other cations, due to the increase in their size, drift away from the cavity center towards the rim of the cavity exhibiting weak cation-π interactions. Energy decomposition analysis (EDA) reveals that the electrostatic and polarization effects act as the major driving force in these interactions. The important outcome of the current study is that the stability of precursor and product ions is found to be crucial in the experimental evaluation of binding affinity of Li(+) and Na(+) complexes of CP. The ESI-MS/MS experiments on the cation complexes of different substituted CPs revealed that the binding strength of CPs towards cations is also dependant on the substituents at the meso-position.

C3 symmetric chiral trimethylsumanene was enantioselectively synthesized through Pd-catalyzed syn-selective cyclotrimerization of an enantiomerically pure iodonorbornenone, ring-opening/closing ole...

Comprehension of the basic concepts for the design of systems for CO2 adsorption is imperative for increasing interest in technology for CO2 capture from the effluents. The efficacy of 20 naturally occurring amino acids (AAs) is demonstrated as the most potent CO2 capturing agents in the process of chemical absorption and physisorption through a systematic computational study using highly parametrized M05-2X/6-311+G(d,p) method. The ability of AAs to bind CO2 both in the noncovalent and covalent fashion and presence of multiple adsorption sites with varying magnitude of binding strengths in all 20 AAs makes them as most promising materials in the process of physisorption. The binding energies (BEs) estimating the strength of noncovalent interaction of AAs and CO2 are calculated and results are interpreted in terms of the nature and strength of the various types of cooperative interactions which are present. The study underlines the possibility to engineer the porous solid materials with extended networks by judiciously employing AA chains as linkers which can substantially augment their efficacy. Results show that a significant increase in the CO2···AA affinity is achieved in the case of AAs with polar neutral side chains. Furthermore, the study proposes AAs as effective alternatives to alkanolamines in chemical dissolution of CO2.

Two new heteroleptic ruthenium(II) photosensitizers that contains 2,2′;6,2′′-terpyridine with extended π-conjugation with donor groups, a 4,4′-dicarboxylic acid-2,2′-bipyridine anchoringligandand athiocyanateligandhave been designed, synthesized and fully characterized by CHN,mass spectrometry,UV-visand fluorescence spectroscopies andcyclic voltammetry. The new sensitizers have either 3,5-di-tert-butyl phenyl (m-BL-5) ortriphenylamine(m-BL-6) groups, where the molar extinction coefficient of both the sensitizers is higher than the analogous rutheniumdyes. Both the sensitizers were tested indye-sensitized solar cells using two different redox electrolytes.

A new high molar extinction coefficient organic-ruthenium(II) polypyridyl complex sensitizer (RD-Cou) that contains 2,,6,-tetramethyl-9-thiophene-2-yl-2,3,5,6,6a,11c-hexahydro1H,4H-11oxa-3a-aza-benzoanthracene-10-one as extended -conjugation of ancillary bipyridine ligand, 4,-dicaboxy-2, ,-bipyridine, and a thiocyanate ligand in its molecular structure has been synthesized and completely characterized by CHN, Mass, 1H-NMR, UV-Vis, and fluorescence spectroscopies as well as cyclic voltammetry. The new sensitizer was tested in dye-sensitized solar cells using a durable redox electrolyte and compared its performance to that of standard sensitizer Z-907.

A series of diastereomeric 4S,5S,6R/S-tetrahydropyrano- and 3S,4S,5R/S-tetrahydrofuranochromenylamine derivatives (a/b isomers; 1–26) has been studied under electron ionization (EI) and chemical ionization (CI) conditions. The EI mass spectra of all diastereomeric compounds show two characteristic fragment ions, of which one is formed by retro-Diels-Alder (RDA) reaction from the molecular ion, retaining the charge on the diene fragment, and the other [M–(HNAr)]+ ion by a simple radical loss. The RDA process is more favorable in all b isomers, whereas the radical loss is dominant in all a isomers; based on these two ions it is easy to differentiate the two diastereomers. The collision-induced dissociation (CID) spectra of all the molecular ions also show the same trend, which reflects the stereoselectivity in the formation of the two characteristic fragment ions. The results of theoretical calculations performed are in accordance with the experimental observations. The CI experiments (methane and isobutane) on all the diastereomeric compounds also enabled the differentiation of the isomers. Copyright © 2007 John Wiley & Sons, Ltd.

Two efficient heteroleptic ruthenium (II) complexes, cis-di(thiocyanato)(4,4′-dicarboxylic acid-2,2′-bipyridine)(4,4′-bis(2-(3,5-di tert-butylphenyl)ethenyl)-2,2′-bipyridine) ruthenium (II) (HRD-1) and cis-di(thiocyanato)(4,4′-dicarboxylic acid-2,2′-bipyridine)(4,4′-bis(2-(2,3,5-trimethylphenyl)ethenyl)-2,2′-bipyridine) ruthenium (II) (HRD-2) were synthesized and characterized, which when anchored onto nanocrystalline TiO2 shows efficiency of 5.77 and 4.87% respectively, using durable redox electrolytes.

Three new sterically demanding unsymmetrical zinc phthalocyanines have been designed and synthesized as sensitizers for dye-sensitized solar cells. All three unsymmetrical phthalocyanines have been completely characterized by elemental analyses, mass spectrometry, FT-IR, H-1 NMR, UV-Visible, and fluorescence (steady-state and life-time) spectroscopies as well as electrochemical methods. Photophysical properties (absorption, emission and redox properties) indicate that the LUMO of unsymmetrical phthalocyanines lies above the TiO2 conduction band and HOMO is below the redox electrolyte. The experimental results are supported by DFT/TD-DFT studies. Electrochemical and in-situ spectroelectrochemical studies suggest that the redox reactions belong to the macrocyclic ring-based electron transfer processes. All three unsymmetrical phthalocyanines were tested in DSSC using I-/I-3(-) redox electrolyte system. (C) 2013 Elsevier Ltd. All rights reserved.

A new extended thermo-stable high molar extinction coefficient bipyridyl ruthenium(II) complex “cis-Ru(4,4’-bis(3,5-di-tert-butylphenyl)-2,2’-bipyridine)(Ln)(NCS)2 H101”, where Ln = 4,4’-dicarboxylic acid-2,2’-bipyridine; was synthesized and characterized by 1H-NMR, FT-IR and ESI-MASS spectroscopes. The H101 sensitized solar cell constructed with an active area of 0.54 cm2 in combination with an ionic liquid electrolyte exhibited broader photocurrent action spectrum with solar-to-electric energy conversion efficiency (η) of 5.89 ( $\textbf{\textit{J}}_{\rm SC} =$ 12.14 mA/cm2, $\textbf{\textit{V}}_{\rm OC} =$ 690 V, fill factor = 0.699) under Air Mass (AM) 1.5 sunlight, while the reference ‘cis-Ru(4,4’-dinonyl-2,2’-bipyridine)(Ln)(NCS)2’, Z907 sensitized solar cell exhibited η-value of 5.17% ( $\textbf{\textit{J}}_{\rm SC} =$ 11.93 mA/cm2, $\textbf{\textit{V}}_{\rm OC} =$ 650 V, fill factor = 0.666). TGA analysis of H101 showed extended thermal-stability and under continuous light exposure and aging at 55°C, the DSSC retained 85% of its initial η-value, while under comparable conditions Z907 sensitized solar cell retained 88%. As compared to 4,4’-dinonyl-2,2’-bipyridine in Z907, the new ancillary bipyridyl ligand ‘4,4’-bis(3,5-di-tert-butylphenyl)-2,2’-bipyridine’ in H101 shifts the absorption bands remarkably towards blue. The Density Functional Theory (DFT) and Time-Dependent DFT excited state calculations of the new sensitizer show that the first three HOMOs have t2g character with sizeable mixing from the NCS ligands with π-bonding orbitals of 4,4’-bis(3,5-di-tert-butylphenyl)-2,2’-bipyridine. The LUMO is a π*-orbital localized on the 4,4-dicarboxylic acid-2,2’-bipyridine and higher un-occupied frontier orbitals have π*-combinations with 4,4’-bis(3,5-di-tert-butylphenyl)-2,2’-bipyridine.