Electron Acceptor Groups Research Articles

Synthesis and solvatochromism of dipodal and tripodal dyes derived from Brooker’s merocyanine

Brooker’s merocyanine (BM) is a classic solvatochromic probe, which exhibits a band in the visible region sensitive to changes in the polarity of the medium. BM shows a reversion in its solvatochromism, which has inspired much research on studies involving different families of dyes. We synthesized four novel dipodal and tripodal solvatochromic dyes (1b–4b) inspired by BM molecular structure. Characterization of the compounds in their protonated form used spectrometric and differential scanning calorimetry techniques. Dyes 1b–4b have an electron–donating phenolate moiety connected through a CHCH conjugated bridge to two or three N–methylpyridinium electron–acceptor groups. The probes exhibit negative solvatochromism in the solvents studied, showing very different colors with the change in the polarity of the solvent. Multiparameter strategies of Kamlet–Abboud–Taft (KAT), Catalán, and a modified KAT fitted the experimental data. The HBD acidity of the solvent represented the main contribution to the solvation of the probes. Performing electronic–structure calculations of the compounds at LC–BLYP/ma–def2–SVP/D4 level and employing water and DMSO as implicit solvents (SMD model) using software ORCA5.0 revealed that the longest–wavelength absorption bands in the dyes are due to a π → π* transition, from the phenolate (electron–donating) group to the N–methylpyridinium (electron–acceptor) groups. The calculations did not reproduce the experimentally observed negative solvatochromism of the dyes in the solvents studied. However, comparing the theoretical and experimental data of the present study with data from the literature provided important information regarding the results obtained.

A computational approach for screening carbazole based organic dyes as potential photosensitizers for DSSCs application

The scientific community has shown significant interest in organic materials due to their potential applications in optoelectronics. In this study, we present the design and theoretical investigation of a new class of carbazole-based organic chromogens (R1-6). These chromogens consist of a heteroaromatic carbazole unit as an electron-rich donor, connected to a substituted phenyl ring carrying various electron acceptor groups. Specifically, we analyse the structural impact of electron withdrawing moieties such as carboxylic acid (–COOH), cyano (–CN), and nitro (–NO2) on the photophysical properties of these chromogens. To gain insights into the electron density localization and charge transfer characteristics, we perform DFT, TD-DFT, and MESP calculations. The computational studies indicate that these materials exhibit promising potential as sensitizers for applications in dye-sensitized solar cells (DSSCs).

An experimental and DFT investigations of fused ring anthracenyl chalcones with effective modification in acceptor moiety: Nonlinear optical and optical limiting response

AbstractThe significance of the anthracene moiety on nonlinear optical (NLO) characteristics is thoroughly examined. The presence of strong electron donor and acceptor groups, large and prolonged conjugation transfer axis, amplifies the push–pull action and increases NLO responses. The values of χ3 obtained for AC derivatives are considerably larger (10−3 esu), indicating that they accurately reflect NLO reactions. According to the optical limiting (OL) investigation, AC has a strong limiting behavior with action beginning at 1.6 KW/cm2. The relationship between transmittance and intensity has demonstrated their potential use in OL applications. Nonlinear optical studies show that all conjugated anthracene chalcones are potential materials for OL devices.

Symmetry‐Broken Charge‐Transfer Excited State in Homoleptic Zinc(II) Imidazo[1,2‐a]pyridine Complexes

AbstractA series of four homoleptic cationic ZnII complexes (Zn1–Zn4) coordinated by two substituted bis‐imidazo[1,2‐a]pyridine (ImPy) ligands (L1–L4) is herein presented. The ligands are functionalized with either electron acceptor or donor functional groups at the C6 positions of the two ImPy moieties. In DMF solution, all of the complexes display intense near‐UV to blue emission (λem=379–450 nm) with high photoluminescence quantum yields (PLQY) up to 0.50 and short‐lived excited states. Additionally, complex Zn4, containing the ‐NPh2 functionalized ligand, displays an interesting solvatochromic behavior. The absorption spectrum is characterized by electronic transitions with mainly ligand‐centered (1LC) and intraligand charge‐transfer (1ILCT) character, which involves a symmetric electron density redistribution at Franck‐Condon (FC). In stark contrast, the subsequent excited‐state dynamics relaxes the molecular symmetry and allows symmetry‐breaking hole‐electron pair redistribution on the bichromophoric system. As a consequence, an efficient radiative de‐excitation process takes place that is ascribed to a singlet‐manifold excited state with symmetry‐broken charge transfer (1SBCT) character, as supported by an in‐depth photophysical, electrochemical and time‐dependent density functional theory (TD‐DFT) investigation. Remarkably, the 1SBCT nature provides structureless green photoluminescence in the solid state (λem up to 520 nm for Zn4), which is rather uncommon for ZnII complexes.

Tuning Mechanically Interlocked Molecules to Recognize Anions and Cations: A Computational Study.

Ions appear as active components in diverse materials. Here, the bonding energy between mechanically interlocked molecules (MIMs) or their acyclic/cyclic molecular derivatives and i) Cl- and Br- ions and/or ii) Na+ and K+ ions, have been investigated. The chemical environment provided by MIMs is less preferably to recognize ionic species compared to unconstrained interactions that are furnished by acyclic molecules. However, MIMs can be more adequate structures for ionic recognition than cyclic compounds if a chemical arrangement of the bond sites that relevantly support more favorable interactions with ions compared to Pauli repulsive ambient is provided. The hydrogen replacement by electron donor (-NH2 ) or acceptor (-NO2 ) groups in MIMs favors the anion/cation recognition due to decreased Pauli repulsion energy and/or more attractive non-covalent bonds. This study clarifies the chemical environment provided by MIMs to interact with ions and highlights these molecules as relevant structures to realize ionic sensing.

Efficient cavity-enhanced adsorption and recovery of low-concentration ammonia on pillar[5]arenes

Ammonia (NH3) capture has great implications for environmental protection and resource recovery. Developing effective and recyclable adsorbent materials to remove low-concentration NH3 in industrial waste gas is critical. Here, solid adsorbents per-hydroxylated pillar[5]arene (OHP[5]) and pillar[5]quinone (P[5]Q) with well-designed functional groups were synthesized and evaluated for NH3 adsorption. The results showed that both materials have high NH3 uptake capacity and excellent cycle stability. P[5]Q showed higher NH3 capacity (15.4 mmol/g) than OHP[5] (11.5 mmol/g) at ambient conditions (293.2 K and 1.0 bar). Dynamic breakthrough experiments showed that P[5]Q had good separation performance on low concentration NH3. Characterizations (including FTIR, SEM, and XPS) and density functional theory (DFT) studies revealed that the adsorption strength for NH3 on P[5]Q possessing CO groups was stronger than OHP[5] composed of phenolic hydroxyls. Also, the electron-accepting CO groups on P[5]Q could change the intramolecular charge distribution, in which an amount of NH3 enters and stores in the electron-deficient internal cavity of P[5]Q. It is demonstrated that P[5]Q with the suitable cavity has good potential for separating low concentration NH3 from industrial waste gas.

Synthesis and spectral properties of symmetrically arylated BODIPY dyes: Experimental and computational approach

In this study, a series of symmetrically arylated BODIPY dyes were synthesized using a pre-functionalization method, and their structures were characterized by several spectroscopic methods. The relationship between the aryl substitution pattern and the photophysical and electrochemical properties of the dyes was investigated using experimental and computational methods. It was found that electron-donating π-conjugated groups at the meso position and electron-accepting π-conjugated groups at the C3/C5 position led to blue-shifted spectra, while the opposite substitution pattern resulted in red-shifted spectra. Additionally, inductive electron-donating alkyl groups at the meso position produced a blue spectral shift and an alkyl group at the meso position significantly increased the fluorescence quantum yield compared to the arylated counterparts. Computational investigations revealed that a thioanisyl group at the C3/C5 position resulted in a significantly narrow band gap. These results provide valuable insights into the design and development of new BODIPY dyes with tailored properties for various applications.

NIR-absorbing donor–acceptor molecules based on fused thienopyrroloindole

Two novel aromatic compounds containing thieno[2',3':4,5]-thieno[3,2-b]thieno[2' ' , 3' ':4' ,5']thieno[2',3':4,5]-pyrrolo[3,2-g]indole as the electron-donating center and terminal 3-(dicyanomethylene)indan-1-one (or 5,6-difluoro analogue) electron-accepting groups exhibit efficient light absorption in the red and near-infrared spectral regions, have low levels of the highest occupied molecular orbital (up to –5.65 eV) and lowest unoccupied molecular orbital (–3.91 eV) and a relatively low band gap value (up to 1.74 eV). The optical, thermal and structural properties are explored and compared with those of their closest and well known analogues, Y5 and Y6.

Reactivity of electrophilic cyclopropanes.

Cyclopropanes that carry an electron-accepting group react as electrophiles in polar, ring-opening reactions. Analogous reactions at cyclopropanes with additional C2 substituents allow one to access difunctionalized products. Consequently, functionalized cyclopropanes are frequently used building blocks in organic synthesis. The polarization of the C1-C2 bond in 1-acceptor-2-donor-substituted cyclopropanes not only favorably enhances reactivity toward nucleophiles but also directs the nucleophilic attack toward the already substituted C2 position. Monitoring the kinetics of non-catalytic ring-opening reactions with a series of thiophenolates and other strong nucleophiles, such as azide ions, in DMSO provided the inherent SN2 reactivity of electrophilic cyclopropanes. The experimentally determined second-order rate constants k 2 for cyclopropane ring-opening reactions were then compared to those of related Michael additions. Interestingly, cyclopropanes with aryl substituents at the C2 position reacted faster than their unsubstituted analogues. Variation of the electronic properties of the aryl groups at C2 gave rise to parabolic Hammett relationships.

Solvent Effects on the Photoinduced [6π]-Electrocyclization Reactions of Mono-, Di-, and Trisubstituted Arylamines: Photophysical, Preparative Photochemistry, and Mechanistic Investigations

The substituent and solvent effects on the spectroscopic behavior and on the photoinduced [6π]-electrocyclization reaction of substituted triphenylamine derivatives have been investigated. Direct irradiation of triphenylamines bearing electron-donor substituents in different solvents has provided for the first time the substituted exo/endo carbazole derivatives from modest to good yields, whereas triphenylamines bearing electron-withdrawing substituents did not provide the carbazoles due to the formation of charge transfer complexes (CTCs). A corollary of the experiments purports that the photoreaction is favored with weak electron-acceptor groups in polar solvents. The lowest-frequency absorption bands of the triarylamines (π,π* electronic transitions) displayed bathochromic shifts as the solvent polarity is increased. The fluorescence emission spectra of triarylamines bearing electron-donor substituents behave as mirror images of the lowest absorption bands, showing dependence on the solvent polarity. Conversely, triarylamines bearing formyl, acetyl, and nitro groups formed CTCs behaving as good fluorescence chromophores in polar solvents. Hammett correlations on the ΔE(0,0) energies of monosubstituted amines showed a bell-shape behavior where the ρ values depended on the solvent polarity. The physical quenching of the photoreaction of triarylamines has demonstrated for the first time that the triplet excited state is univocally the photoreactive state leading to exo/endo carbazole derivatives.

Unravelling the effect of donor-π-acceptor architecture in designing 1,3-indanedione based sensitizers for DSSC applications

• 1,3-indanedione-based electron-acceptor group has been employed in designing new sensitizers and theoretical calculations of the nine sensitizers, that are designed based on D-π-A architecture, were performed at DFT and TDDFT level. • HOMO-LUMO energy levels of the designed dyes are matching with the energy levels of titania and redox couples. • Frontier molecular orbital (FMO) analysis revealed intra-molecular charge transfer from the electron-donor to the 1,3-indanedione electron-acceptor. • Two-fold enhancement of dipole moment was observed in all sensitizers upon binding on (TiO 2 ) 9 nanocluster. • The simulated electronic spectra of free dyes and Dye@TiO 2 encompass the entire visible region. • Phenoxazine (POZ) and phenothiazine (PTZ) electron-donor moieties significantly improved the chemical reactivity and photophysical properties and therefore, corresponding RK4 and RK5 sensitizers are better than others. • The D-π-A architecture is found to be better than D-π-A-D architecture in the case of 1,3-indanedione-based sensitizers. Molecular engineering plays a vital role in the design of efficient organic sensitizers for DSSC applications. The study highlights the density functional theory calculations of nine organic sensitizers, designed based on a new 1,3-indanedione electron-acceptor cum anchoring group. The new sensitizers (RK1-9) have been designed by tailoring a modified 1,3-indanedione electron-acceptor with conventional electron-donors in the form of D-π-A architecture. Geometry optimization studies reveal that the RK7 & RK8 molecules have more twisted geometries. Similarly, the RK5 dye has the smallest energy gap of 2.34 eV compared to other dyes. LUMO energy levels of all the designed dyes are positive, found above the conduction band energy level, and the HOMO energy levels were more negative than the redox potentials. Calculated electrochemical parameters suggest that the dyes RK1-5 and RK9 inject the electrons efficiently into the conduction band of TiO 2 . Further, the Gibbs free energies of the dyes indicate that the RK4 and RK5 dyes regenerate much faster than the other dyes. The electronic absorption spectra of the RK dyes were steadily shifting towards the longer wavelength region with solvent polarity and further red-shifts upon adsorbing on the (TiO 2 ) 9 nanocluster. The LUMO and LUMO+1 wave functions of the RK dye@(TiO 2 ) 9 complexes are confined to the (TiO 2 ) 9 nanocluster, suggesting effective intramolecular charge transfer upon photo-excitation. Overall, the computational study demonstrates the significance of the 1,3-indanedione electron-acceptor and o the D-π-A architecture in the molecular design of new organic sensitizers for DSSC applications.

Tautomeric Equilibrium in 1-Benzamidoisoquinoline Derivatives.

In this study, the tautomeric equilibrium of a sequence of 1-benzamidoisoquinoline derivatives was investigated with the tools of NMR spectroscopy and computational chemistry. The equilibrium between different tautomers in these systems could be controlled via the substitution effect, and the relative content of the amide form varied from 74% for the strong electron-donating NMe2 substituent to 38% for the strong electron-accepting NO2 group in the phenyl ring. In contrast to the previously investigated 2-phenacylquinoline derivatives, the most stable and thus most abundant tautomer in the 1-benzamidoisoquinoline series except the two most electron-accepting substituents was an amide. The intramolecular hydrogen bond present in the enol tautomer competed with the intermolecular hydrogen bonds created with the solvent molecules and thus was not a sufficient factor to favor this tautomer in the mixture. Although routinely computational studies of tautomeric equilibrium are performed within the continuum solvent models, it is proven here that the inclusion of the explicit solvent is mandatory in order to reproduce the experimental tendencies observed for this type of system, facilitating strong intermolecular hydrogen bonds.

Synthesis, photophysical and electrochemical properties of π-conjugated pyrene based down-shifting molecules with fluorinated aryl groups

Pyrene molecule, with excellent photophysical properties (strong absorption cross section, excellent emission properties and a long-excited state lifetime), excellent thermal and photochemical stability, has been widely used as a building block for the synthesis of pyrene-based fluorophores for optoelectronic applications. In this work, we report the synthesis of two series of pyrene–π–A compounds, series I (3–6) and II (10–13), in which nitro, cyano, cyanoacrylonitrile and cyanoacrylic acid as electron acceptor groups are connected to the pyrene core via aryl or fluoroaryl π-conjugating bridges. The incorporation of fluorine atom on the π-extension bridge cause a slightly red-shift at emission wavelength (λem) in solution and polymethylmethacrylate (PMMA) films and increase the Stokes shift due to greater stabilization of molecular orbitals in the excited state, especially for series I. Solvatochromic measurements and theoretical computational studies suggest a higher intramolecular charge transfer in the excited state for series II when compared to series I due to their stronger electron acceptor moieties. All pyrene derivatives are stable and exhibited initial mass loss at temperature above 200 °C. The good photophysical and thermal properties of the synthesized pyrene derivatives, associated with high molar absorption coefficients in the UV spectrum and good fluorescence emission in the range of 430–480 nm (series I) and 505–567 nm (series II) in PMMA films, make them possible candidates for organic light-emitting diode (OLED) and luminescent down-shifting (LDS) layers for stable perovskite solar cells, respectively.

Intramolecular charge transfer for optical applications

Tuning of intramolecular charge transfer (ICT) in a molecule could be used to modulate its linear and nonlinear optical (NLO) response properties. Over the years, the ICT process in the so-called “push–pull” molecules in which electron donor (D) and acceptor (A) groups are connected either directly or through a π-electron bridge has been used for emission color tuning, modulating absorption maxima, optimizing first or higher order hyperpolarizabilities, and two-photon absorption (TPA), among others. As ICT is the functional basis of many optoelectronic and semiconductor devices, optimizing the parameters involved in this process as well as modeling the effect of the environment and intermolecular interaction are crucial for these applications. NLO processes such as second harmonic generation, sum-frequency generation, and TPA have been used extensively for numerous technological applications, such as optical switching, optical limiting, bioimaging, and biophotonics. Recently, through-bond and through-space ICT have been employed to tune the reverse intersystem crossing that facilitates thermally activated delayed fluorescence for fabricating next-generation organic light-emitting diodes. Aggregation-induced emission of ICT molecules either alone or in combination with the other phenomenon, such as TPA, could be useful in many optical applications. In this perspective, the state-of-the-art and challenges in designing ICT-based molecules and materials for optical applications will be discussed. The underlying theories used to quantify the magnitude of ICT and NLO response are mentioned, followed by a discussion on the latest development and scope of using these molecules and materials for optical applications.

Thiophene and diaminobenzo- (1,2,5-thiadiazol)- based DAD-type near-infrared fluorescent probe for nitric oxide: A theoretical research.

A near-infrared fluorescent probe (LS-NO) for the real-time detection of nitric oxide (NO) in inflammatory bowel disease (IBD) was developed recently. The probe used oligoglycol morpholine-functionalized thiophene as strong electron donors and diaminobenzene (1,2,5-thiadiazole) as a weak electron acceptor and NO trapping group. It could detect exogenous and endogenous NO in the lysosomes of living cells with high sensitivity and specificity. To further understand the fluorescent mechanism and character of the probes LS-NO and LS-TZ (after the reaction of the probe LS-NO with NO), the electron transfer in the excitation and emitting process within the model molecules DAD-NO and DAD-TZ was analyzed in detail under the density functional theory. The calculation results indicated the transformation from diaminobenzene (1,2,5-thiadiazole) as a weak electron acceptor to triazolo-benzo-(1,2,5-thiadiazole) as a strong electron acceptor made LS-NO an effective "off-on" near-infrared NO fluorescent probe.

Cation recognition controlled by protonation or chemical reduction: a computational study.

To control biochemical processes, non-covalent interactions involving cations are activated by protons or electrons. In the present study, the bonding situation between: (i) carboxylic acid or (ii) ferrocene-functionalized crown ether derivatives and cations (Li+, Na+ or K+) has been elucidated and, mainly, tuned by the substitution of hydrogen atoms by electron donor (-NH2) or acceptor (-NO2) groups. The deprotonation of the carboxyl groups improves the interaction with the cations through more favorable electrostatic O⋯cation interactions. Reducing the ferrocene structures favors cationic recognition supported by a less unfavorable iron⋯cation binding. The receptors preferably interact with smaller cations because of more attractive electrostatic and orbital (σ or π) O⋯cation interactions. The presence of electron donor or acceptor groups in the carboxylic acid-functionalized crown ethers promotes less attractive interactions with the cations, mainly due to the less favorable electrostatic O⋯Na+ interactions. The -H → -NH2 substitution in the ferrocene framework favors the cationic recognition. It is based on the strengthening of the electrostatic and σ O⋯Na+ and H2N⋯Na+ bonds. The (i) absence of repulsive electrostatic iron⋯cation interactions, or (ii) the presence of oxygen atoms with large electron density, ensures carboxylic acid-functionalized crown ethers have more favorable interactions with cations than ferrocene compounds. Therefore, this work has demonstrated how cation recognition can be improved by structural changes in carboxylic acid- or ferrocene-functionalized crown ethers and has shown that the carboxylic acid molecules appear to be better candidates for cation recognition than ferrocene derivatives.

Conformationally confined three-armed supramolecular folding for boosting near-infrared biological imaging.

Herein, a triphenylamine derivative (TP-3PY) possessing 4-(4-bromophenyl)pyridine (PY) as an electron-accepting group and tris[p-(4-pyridylvinyl)phenyl]amine (TPA) with large two-photon absorption cross-sections as an electron-donating group was obtained, and showed intense absorption in the visible light region (λmax = 509 nm) and weak near-infrared (NIR) fluorescence emission at 750 nm. After complexation with cucurbit[8]uril (CB[8]), TP-3PY showed bright NIR fluorescence emission at 727 nm and phosphorescence emission at 800 nm. When the supramolecular assembly (TP-3PY⊂CB[8]) further interacted with dodecyl-modified sulfonatocalix[4]arene (SC4AD), the fluorescence and phosphorescence emissions were further enhanced at 710 and 734 nm, respectively. However, only the fluorescence emission of TP-3PY was enhanced in the presence of cucurbit[7]uril (CB[7]) and SC4AD. More interestingly, the photoluminescence of TP-3PY⊂CB[8]@SC4AD and TP-3PY⊂CB[7]@SC4AD assemblies could be excited by both visible (510 nm) and NIR light (930 nm). Finally, these ternary supramolecular assemblies with bright NIR light emission were applied to lysosome imaging of tumor cells and real-time biological imaging of mice.

Paracyclophane-based bipolar near-ultraviolet emitters showing advanced circularly polarized luminescent properties

<p>As linking unit, [2.2]paracyclophane (PCP) has been inserted in between electron-donating groups (<em>i.e.</em> carbazole and 10<em>H</em>-phenoxazine) and electron-accepting groups (<em>i.e.</em> triphenyl-1,3,5-triazine and diphenylsulfone) to prepare a series of linear bipolar racemic near-ultraviolet (NUV) emitters owing to the planar chirality associated with the PCP. In toluene, the racemic bipolar PCP-based emitters can show emission wavelength in the range of 400-444 nm. Critically, very small Commission Internationale de L��Eclairage (CIE) chromaticity coordinate of y value of 0.03 has been achieved for the photoluminescent spectra of these bipolar racemic NUV emitters in solution. The PCP-based bipolar emitters can show efficient NUV emission with photoluminescent quantum yields (PLQY) of <em>ca.</em> 0.5 in doped mCP film. In addition, the enantiomers of the NUV emitters have been obtained to show obvious circular dichroism (CD) behavior and circularly polarized luminescence (CPL). The absorption asymmetric factor (<em>g</em><sub>abs</sub>) of <em>ca.</em> 4.4��10<sup>-4</sup> and photoluminescent asymmetric factor (<em>g</em><sub>PL</sub>) of <em>ca.</em> 1.5��10<sup>-3</sup> can be achieved by the PCP-based NUV enantiomers. After doped in the emission layer of organic light-emitting diodes (OLEDs), efficient NUV and deep blue-emitting OLEDs have been constructed. The NUV OLEDs based on the racemic emitters can achieve forward-viewing maximum external quantum efficiency (<em>��</em><sub>ext</sub>) of 5.03% and electroluminescence (EL) peak at 404 nm with CIE<sub>y</sub> of 0.05, while the OLEDs with deep blue emission can show <em>��</em><sub>ext</sub> of 4.12% and EL peak at 412 nm with CIE<sub>y</sub> of 0.08. Furthermore, the NUV chiral enantiomers can bring <em>��</em><sub>ext</sub> of 5.25% and EL peak at 404 nm with CIE<sub>y</sub> of 0.05, while the deep blue chiral enantiomers can give <em>��</em><sub>ext</sub> of 4.40% and EL peak at 412 nm with CIE<sub>y</sub> of 0.08. Clearly, these encouraging EL data show the great potential of these linear PCP-based bipolar emitters in the field of OLEDs.</p>

Directionality and additivity effects of molecular acidity and aromaticity for substituted benzoic acids under external electric fields.

Our recent study [M. Li et al.Phys. Chem. Chem. Phys., 2023, 25, 2595-2605] unveiled that the impact of an external electric field on molecular acidity and aromaticity for benzoic acid is directional, which can be understood using changes in frontier orbitals and partial charges. However, it is unclear if the effect will disappear when substituting groups are present and whether new patterns of changes will show up. In this work, as a continuation of our efforts to appreciate the impact of external electric fields on physiochemical properties, we find that the directionality effect is still in place for substituted benzoic acid derivatives and that there exists the additivity effect with respect to the number of substituent groups, regardless of the direction of the applied field and the type of substituting groups. We confirm the findings using electron-donating and electron-accepting groups with the electric field applied either parallelly or perpendicularly to the carboxyl group along the benzene ring. The directionality and additivity effects uncovered from this work should enrich the body of our knowledge about the impact of external electric fields on physiochemical properties and could be applicable to other systems and properties as well.

Studying of 2,2′-Bipyrimidine Based Dyes Properties as Photo-Sensitizer for Dye Sensitized Solar Cells (DSSCs)

In this investigation, five novel π-new organic donor-π-acceptor dyes (D-π-A) based on 2,2′-bipyrimidines were used. For optimization and DFT research, respectively, the 6-311+G(d,p) basis set and B3LYP density functional theory were applied. In all the systems, diphenyl amine moiety acts as the electron-donor component, whereas the nitro/cyano moiety as electron acceptor (anchoring) group. In the conjugated spacer, a methyl/ethyl substituent was used to examine the impact of the auxiliary donor group. The computed HOMO-LUMO gap and the spectral data matched well. The oscillator strength (f), electron injection free energy (ΔGinject) and light-harvesting efficiency (LHE) were also computed and explained. The calculated values for the examined dye-sensitizers open-circuit photo voltage (Voc) and electron coupling constant (VRP) were also included in this research. This study demonstrates that every synthetic dye has promising potential as a dye sensitized solar cells (DSSCs) sensitizer.