HOMO-LUMO Levels Research Articles

Heterocoronenes Containing Pyridine and 1,2-Azaborine Units.

Several coronenes containing pyridine and azaborine units have been readily prepared and structurally confirmed by X-ray crystallographic analysis. The codoping results in interesting findings and properties such as the first observation of BN-H---NPy hydrogen bonds in crystals of BN-PAHs, short π-π stacking distances, lowered HOMO-LUMO levels, narrow band gap, and unique dual response to fluoride ion and proton in solution.

Optical Properties of Disulfiram and Its Metal Complexes Toward the Photoactive Anticancer Effects

Introduction Disulfiram (DSF) has been used for nearly 70 years as an antidrug and is clinically safe. Recently, it has attracted widespread attention, because it was shown through screening to be effective as an anticancer agent. 1) However, further improvement of the efficacy of DSF is required before it can be used as a therapeutic agent. In this study, we focused on metal diethyldithiocarbamate complexes formed by DSF and metal ion (Cu2+, Fe3+), respectively, to improve the efficacy of the drug by applying it to photodynamic therapy. It aimed to enhance the photoresponses of DSF, with Cu complex (DSF-Cu) and Fe complex (DSF-Fe), and to further improve the anticancer effects with the enhanced photoresponses. Methods Cyclic voltammetry (CV) measurements were performed to determine the electrochemical response of each sample and to investigate their redox properties. In addition, electrochemical impedance spectroscopy (EIS) measurements were conducted under both UV light and dark conditions using a carbon plate coated with the samples as the working electrode to investigate the photo-responsiveness of the samples. Methylene blue (MB) degradation tests were then carried out based on JIS R 1703-2: 2014 to assess whether light irradiation of each sample improves the degradation of organic matter. The HOMO-LUMO levels were estimated by photoelectron yield spectroscopy (PYS) measurements and diffuse reflectance spectroscopy. Results and Discussion From CV results, it could be clearly found the oxidation and reduction peaks for DSF, DSF-Cu, and DSF-Fe, indicating that all samples exhibit an electrochemical response. The EIS results also showed that the radius of the capacitive semicircle was reduced by UV irradiation for all samples, which is considered to be due to the decrease in charge transfer resistance as the charge carriers are transferred more efficiently by UV irradiation. The MB degradation test showed a relatively clear MB degradation rate for DSF-Fe (Figure 1). The reason for the difference in MB degradation rates among the samples can be considered to be the difference in reactive oxygen species (ROS) production ability based on the relationship between the HOMO-LUMO gap position and the oxidation/reduction potentials of water and oxygen in each sample. From the estimated HOMO-LUMO level of each sample, it could find that the reduction potential of oxygen (O2/O2 ―: -0.46 V at pH 7) was below the LUMO level in all samples, but the oxidation potential of water (O2/H2O: 0.81 V at pH 7) and the oxidation potential of MB potential (>1.2 V) did not exceed the HOMO level (Figure 2). Therefore, it is possible that MB was oxidatively decomposed by O2 ― produced by the sample's own oxidation and reduction of dissolved oxygen. The difference in the decomposition rate may be due to the difference in the recombination speed of excited electrons. The respective gap energies suggest that DSF-Cu and DSF-Fe can also respond to visible light.[References](1) Yuya Terashima, et al., Nature Communications 11 (609), 2020.(2) S. Trasatti, Pure & Appl Chem. 58 (7), 955-966, 1986. Figure 1

(Invited) Development of Fused Porphyrin Sensitizers for Efficient Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) have attracted considerable attention as an alternative to silicon-based solar cells due to their potential advantages in terms of power conversion efficiency, production cost, design flexibility, and indoor use. Because the photovoltaic performance of DSSCs strongly depends on sensitizers, various kinds of sensitizers have been developed. Among them, porphyrin sensitizers have made remarkable contribution to performance improvement in DSSCs. The push–pull type porphyrin sensitizers have displayed excellent light-harvesting ability and demonstrated high power conversion efficiencies more than 10% in DSSCs.Meanwhile, incorporation of aromatic-fused structure into a porphyrin core is a fascinating option for highly efficient DSSCs because of direct π-expansion of the porphyrin core and resultant red-shifted absorption. However, aromatic-fused porphyrin sensitizers have suffered rather low cell performances due to their mismatch of HOMO-LUMO levels, high aggregation tendency, and short lifetime of the excited states. Bearing these in mind, we envisioned that the introduction of methylene-bridged fused structure into a porphyrin core would overcome these drawbacks, boosting the cell performance. In this context, we designed and synthesized a series of methylene-bridged thiophene-fused porphyrin sensitizers and revealed that the DSSC of thiophene-fused porphyrin sensitizer achieved the highest power conversion efficiency ever reported for DSSCs with aromatic-fused porphyrin sensitizers. Furthermore, rational molecular design can realize further enhancement of the photovoltaic performance of the DSSCs with thiophene-fused porphyrin sensitizers.

Diarenofuran[b]-fused BODIPYs: One-Pot SNAr-Suzuki Synthesis and Properties.

We present a streamlined methodology that integrates regioselective tetrahalogen-BODIPY and o-hydroxyphenylboronic acid in a one-pot process, leveraging SNAr nucleophilic substitution in conjunction with Suzuki coupling to afford diarenofuran [b]-fused BODIPYs (DBFB1-9) with commendable yields (85-95%) and short reaction times (0.5-1.0 h). X-ray structure analyses of DBFB5,7-9 elucidate that these diarenofuran[b]-fused BODIPYs adopt a "butterfly" conformation, maintaining a highly rigid planarity. A comprehensive examination of the spectroscopic and electrochemical properties of these diarenofuran[b]-fused BODIPY derivatives, incorporating various substituents, reveals intriguing characteristics, including pronounced absorption and emission in the near-infrared region (NIR), elevated fluorescence quantum yields (ΦF = 75-89% in dichloromethane), and tunable HOMO-LUMO levels. Remarkably, compared to DBFB1-8, DBFB9 possesses a large extended π-conjugated system, resulting in significant red shifts in its absorption and emission maxima, reaching 623 and 635 nm, respectively, and a reduced HOMO-LUMO gap. Despite this substantial structural expansion, DBFB9 maintains a surprisingly high fluorescence quantum yield (ΦF = 80%), underscoring its exceptional photophysical performance and strong potential for applications requiring efficient NIR emission and robust fluorescence retention.

Exploring deep eutectic solvents of methane sulfonic acid and choline chloride: Formation, properties, and metal solvent effectiveness

Methane sulfonic acid (MSA), a hydrogen bond donor (HBD), was combined with choline chloride (HBA) at varying molar ratios (1:1, 1:2 and 2:1) to explore the formation of deep eutectic solvents (DES). The resulting blends, at 1:1 and 2:1 ratio, remained liquid at ambient temperature. Among these combinations, the DES formed with a 1:1 molar ratio (MSA-ChCl) exhibited the highest decomposition temperature (166 °C) followed by MSA-ChCl (1:2) and MSA-ChCl (2:1). Alongside, the glass transition temperature of the DES also remained relatively unaffected by the molar ratio of its components. Notably, both density and viscosity were observed to be temperature dependent. To elucidate hydrogen bonding interactions between choline chloride and MSA, Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy were employed. The broadening and shifting of IR peaks illustrate the formation of intermolecular bonding between MSA and ChCl. Density Functional Theory (DFT) calculations were conducted to optimise molecular structures, analyse HOMO-LUMO levels, estimate electronegativity and ionization potential, and generate electrostatic potential surfaces of the DES. As per calculated Molecular Electrostatic Potential (MEP) by DFT of pure MSA and ChCl, SO of MSA has most electron deficient region and it has potential to interact with electron positive OH part of ChCl, which is also demonstrated by IR spectra. MSA-ChCl (2:1) displayed the most negative electron density and proved to be the most effective metal solvent among the DES formulations tested. Exceptional solubility of lithium in MSA-ChCl (2:1) was observed, exceeding 105 mg/L. Moreover, zinc, copper, cobalt, and iron also demonstrated good solubility in MSA-ChCl (2:1), ranging from 105 to 104 mg/L.

Finely tuned energy gaps in host-guest complexes: Insights from belt[14]pyridine and fullerene-based nano-Saturn systems

Over the past few decades, doping, physisorption and chemisorption remained some of the commonly utilized methods to modify the energy gaps and electronic properties of materials. Yet, achieving precise control over tuning the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels within these systems persisted as a remarkable challenge. Therefore, there is a growing need for systems that facilitate exact adjustments of energy gaps and HOMO/LUMO levels. Here, in this research work, the nano-Saturn host-guest complex systems are designed based on belt[14]pyridine as a host and fullerene nanocages (C20, C32, C34 and C36) as guests. The greater thermodynamic stability of the complexes is revealed by the higher values of interaction energies (Eint) for these complexes, ranging from −45.50 to −56.81 kcal/mol. The frontier molecular orbital (FMO) analysis revealed the contribution of HOMO of fullerenes and LUMO of belt[14]pyridine towards the HOMO and LUMO of the designed complexes, respectively. The energy gaps of the complexes also decrease compared to the constituents, with the least Egap of 0.52 eV observed for C20@N-belt. Moreover, the charge transfer from the host towards the guests is predicted and confirmed via natural bond orbital (NBO) and electron density difference (EDD) analyses. The non-covalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) analyses determine the nature and strength of interactions in the host-guest complexes. Moreover, it is noticed through the UV–vis analysis that the bare fullerenes show the maximum absorption in ultraviolet (UV) region, but after complexation, maximum absorption is observed in visible and near infrared (NIR) regions, with highest λmax of 927 nm for C36@N-belt. These findings highlight the successful development of nano-Saturn host-guest complexes with precise control over HOMO-LUMO levels and energy gaps. This work aims to address the challenges in fine-tuning the electronic properties and demonstrates potential applications in optoelectronics, photovoltaics, and NIR-based sensors. Moreover, the ability to tune the electronic properties can guide future material design strategies for advanced energy storage and photonic devices.

INCLUSION OF AZULENE STRUCTURAL UNITS IN THE BASIS OF CONJUGATED POLYMERS: IMPROVEMENT OF PROTON SENSITIVITY AND FLUORESCENCE

The growing interest in aromatic polymer compounds with an extended π-electron coupling system is explained by their importance as functional materials for organic optoelectronics. At present, much attention is paid to arylated, as well as substituted by electron acceptor and/or electron donor groups, aromatic and heteroaromatic compounds. One of the advantages of such conjugated aromatic systems is that they can fine-tune the electronic structure of materials in order to optimize their performance and morphology. In this regard, the structural isomer of naphthalene - azulene is of considerable interest. The nonalternant aromatic hydrocarbon azulene has unique electronic and spectral properties, including a polarized structure with a dipole moment of the order of 1,08 D and abnormal Anti-Kasha fluorescence S2→S0. The article discusses the synthesis of two fluorene-azulene π-conjugated copolymers using the modern methodology of organic synthesis as the Suzuki − Miyaura -cross−coupling reaction. It was shown that the interaction of 1,3-dibromazulene, as well as 2,7-Bis(3-bromoazulen-1-yl)-9,9-dioctyl-fluorene with 2,2'-(9,9-dioctyl-9H-fluorene-2,7-diyl)bis(1,3,2-dioxaborinane) under Suzuki − Miyaura cross-coupling conditions, azulene conjugate copolymers were synthesized: poly[2,7-(9,9-dioctylfluorenyl)-alt-(1ꞌ,3ꞌ - azulenyl)] and poly[1,3-bis(9ꞌ,9ꞌ-dioctylfluoren-2ꞌ-yl)azulenyl]-alt-[1ꞌꞌ,3ꞌꞌ - azulenyl]. It is revealed that neutral solutions of the obtained copolymers are nonfluorescent, but they become luminescent upon addition of trifluoroacetic acid. The «launching» of fluorescence occurs as a result of the formation of a 6 π-electron azulenyl cation, which rearranges the general electronic character of polymers, in particular, HOMO-LUMO levels and band gap. The obtained results demonstrate that the introduction of azulene units into a conjugated polymer framework has great potential for application as new protic functional materials.

Structural and ultrafast third-order nonlinearities of methyl and methoxy substituted anthracene chalcones: Z-scan, four-wave mixing, and DFT approaches

We report on the structural, thermal, linear, and ultrafast third-order nonlinear optical (NLO) properties of two novel anthracene chalcones: (2E)-1-(anthracen-9-yl)-3-(5-methylthiophen-2-yl)prop-2-en-1-one (5ML2SANC) and (2E)-1-(9-anthryl)-3-(2,4,5-trimethoxyphenyl)prop-2-en-1-one (245TMANC). The chalcones were synthesized by Claisen-Schmidt condensation reaction, and the single crystals were grown by the solvent evaporation method. The molecular structure was confirmed by FTIR and NMR spectroscopy, while the crystal structure was determined using the single crystal XRD. Both crystals belong to centrosymmetric monoclinic crystal system with space group P21/n. The Hirshfeld surface was analyzed to understand intermolecular interactions, and the band structures - including HOMO-LUMO levels, excited state energies, GCRDs and MEPs-were studied using DFT. The ultrafast third-order NLO properties were investigated by Z-scan and degenerate four-wave mixing (DFWM) techniques using Ti: Sapphire amplifier laser delivering ∼50 fs pulses at 800 nm (1 kHz, ∼4 mJ, 2 W). Two-photon absorption, positive nonlinear refraction, optical limiting and optical switching behaviors were observed by Z-scan measurements. The time-resolved DFWM show that the decay time of 5ML2SANC is ∼127 fs, while for 245TMANC it is ∼142 fs. The second hyperpolarizability (γ) measured by Z-scan, DFWM and the estimations from the DFT theory are found to be in good agreement (∼10−34 esu). The ultrafast optical response, significant NLO properties and thermal stability of the synthesized chalcones demonstrate their potential suitability in optical limiting and switching applications.

Metallophthalocyanines as Outstanding Hole Transporting Materials in Perovskite Solar Cells

Perovskite solar cells (PSCs) are promising candidates to reach the market to complement the current offer of photovoltaic cells although for such a thing they still have to overcome some challenges such as long-term stability. The hole transporting layer (HTL) is a crucial component in n-i-p PSC, since it must favor an adequate movement of charges and protect the perovskite layer from environmental conditions. In this sense, the commonly used HTL, spiro-OMeTAD, does not provide PSCs with sufficient stability and is too expensive. Cheaper molecular materials such as metallophthalocyanines are proving to be a good alternative, as they provide greater stability.[1]In this communication, we will present novel ZnPcs and CuPcs monomers[2] (see as examples Figure 1), among others, as efficient, stable, and low cost HTMs in PSCs. The MPcs are substituted with functional groups that possesses a very good solubility in a wide range of organic solvents, adequate HOMO LUMO levels and their photovoltaics performance as high stable solution processing in a wide range of perovskite solar cell devices.

Norbornadiene-Quadricyclane Photoswitches with Enhanced Solar Spectrum Match.

Herein, we report monomeric and dimeric norbornadiene-quadricyclane molecular photoswitch systems intended for molecular solar thermal applications. A series of six new norbornadiene derivatives conjugated with benzothiadiazole as the acceptor unit and dithiafulvene as the donor unit were synthesized and fully characterized. The photoswitches were evaluated by experimentally and theoretically measuring optical absorption profiles and thermal conversion of quadricyclane to norbornadiene. Computational insight by density functional theory calculations at the M06-2X/def2-SVPD level of theory provided geometries, storage energies, UV-vis absorption spectra, and HOMO-LUMO levels that are used to describe the function of the molecular systems. The studied molecules exhibit absorption onset ranging from 416 nm to 595 nm due to a systemic change in their donor-acceptor character. This approach was advantageous due to the introduction of benzothiadiazole and the dimeric nature of molecular structures. The best-performing system has a half-life of 3 days with quantum yields over 50 %.

Exploring the Role of Central Metals in Bulky Phthalocyanines for Dye-Sensitized Solar Cells.

Two series of metallo-(Zn(II), Mg(II), and Ru(II)) and free-base phthalocyanines (Pcs) with a carboxyl anchoring group and well-established bulky peripheral substituents (either tert-butyl or bulky 2,6-diisopropylphenoxy) were synthesized and tested as sensitizers in dye-sensitized solar cells (DSSCs). The trend of photovoltaic efficiencies (PCEs) for free-base and metallo Pcs followed the order Zn(II)Pc>Mg(II)Pc≫H2Pc ≈ Ru(II)Pc regardless of the peripheral substitution. Higher efficiencies (4.95 versus 3.63 for the Zn(II) derivatives) were achieved with Pcs bearing the bulkier 2,6-diisopropylphenoxy group, indicating a lower aggregation and more suitable HOMO-LUMO levels. Furthermore, these derivatives showed a morelevant influence of the metal on the PCE values (from the highest 4.95 for the Zn(II)Pc to the lowest 0.23 for the Ru(II)Pc. In both series, the best PCEs observed with the Zn(II) derivatives were mainly due to their highest Jsc values. The lowest efficiencies found for the free-bases and Ru(II) derivatives were attributed to a mismatch between their LUMO levels and the conduction band of the TiO2,and lower light-harvesting capabilities, respectively. In conclusion, Zn(II) derivatives are still the best Pc candidates to use as sensitizers in molecular photovoltaics.

A Review on Self-Assembly Driven Optoelectronic Properties of Polythiophene-Peptide and Polythiophene-Polymer Conjugates.

Polythiophene (PT) is an important conducting polymer for its outstanding optoelectronic properties. Here, we delineate the self-assembly-driven optoelectronic properties of PT-peptide and PT-polymer conjugates, taking examples from recent literature reports. PT-peptide conjugates made by both covalent and noncovalent approaches are discussed. Poly(3-thiophene acetic acid) (P3TAA) covalently coupled with Gly-Gly-His tripeptide, C-protected and deprotected tripeptide H2N-F-F-V-OMe, etc. exhibits self-assembly-driven absorbance, fluorescence, photocurrent, and electronic properties. Noncovalent PT-peptide conjugates produced via ionic, H-bonding, and π-stacking interactions show tunable morphology and optoelectronic properties by varying the composition of a component. PT conjugated with Alzheimer's disease peptide (KLVFFAE, Aβ16-22) shows enhanced photocatalytic water splitting, cationic PT(CPT-I)-perylene bisimide-appended dipeptide (PBI-DY), and anionic PT-perylene diimide-appended cationic peptide (PBI-NH3+) conjugates and exhibits self-assembly-driven enhanced photoswitching and organic mixed electronic and ionic conductivity (OMEIC) properties. In the PT-polymer conjugates, self-assembly-driven optoelectronic properties of covalently produced PT-random copolymers, PT-block copolymers, PT-graft-random copolymers, and PT-graft-block copolymer conjugates are discussed. The HOMO-LUMO levels of hyperbranched polymers are optimized to obtain better power conversion efficiency (PCE) in the bulk heterojunction (BHJ) solar cell than in linear polymers, and P3TAA-ran-P3HT (43 mol % P3TAA) conjugated with MAPbI3 perovskite exhibits higher PCE (10%) than that with only P3TAA hole-transporting material. In the ampholytic polythiophene (APT), on increasing pH, the morphology changes from the vesicle to fibrillar network for the dethreading of the PT chain, resulting in a red shift of the absorbance peak, an enormous increase in PL intensity, lowering of the charge transfer resistance, and an induction of Warburg impedance for the release of quencher I- ions. The PT-g-(PDMAEMA-co-PGLU-HEM) graft copolymer self-assembles with Con-A lectin, causing fluorescence quenching, and acts as a sensor for Con-A with a LOD of 57 mg/L. Varying sequences of the block copolymer containing pH-responsive PDMAEMA and temperature-responsive PDEGMEM grafted to the PT backbone shows different self-assembly, optical, electronic, and photocurrent properties depending on the proximity and preponderance of the block sequence on the PT backbone.

Air-Stable and Eco-Friendly Symmetrical Imine with Thiadiazole Moieties in Neutral and Protonated form for Perovskite Photovoltaics.

This paper proposes molecular and supramolecular concepts for potential application in perovskite solar cells. New air-stable symmetrical imine, with thiadiazole moieties PPL2: (5E,6E)-N2,N5-bis(4-(diphenylamino)benzylidene)-1,3,4-thiadiazole-2,5-diamine), as a hole-transporting material was synthesised in a single-step reaction, starting with commercially available and relatively inexpensive reagents, resulting in a reduction in the cost of the final product compared to Spiro-OMeTAD. Moreover, camphorsulfonic acid (CSA) in both enantiomeric forms was used to change the HOMO-LUMO levels and electric properties of the investigated imine-forming complexes. Electric, optical, thermal, and structural studies of the imine and its complexes with CSA were carried out to characterise the new material. Imine and imine/CSA complexes were also characterised in depth by the proton Nuclear Magnetic Resonance 1H NMR method. The position of nitrogen in the thidiazole ring influences the basicity of donor centres, which results in protonation in the imine bond. Simple devices of ITO/imine (with or without CSA(-) or CSA(+))/Ag/ITO architecture were constructed, and a thermographic camera was used to find the defects in the created devices. Electric behaviour was also studied to demonstrate conductivity properties under the forward current. Finally, the electrical properties of imine and its protonated form with CSA were compared with Spiro-OMeTAD. In general, the analysis of thermal images showed a very similar response of the samples to the applied potential in terms of the homogeneity of the formed organic layer. The TGA analysis showed that the investigated imine exhibits good thermal stability in air and argon atmospheres.

Bicarbazole-Benzophenone Based Twisted Donor-Acceptor Derivatives as Potential Blue TADF Emitters for OLEDs.

Over the past few decades, organic light-emitting diodes (OLEDs) find applications in smartphones, televisions, and the automotive sector. However, this technology is still not perfect, and its application for lighting purposes has been slow. For further development of the OLEDs, we designed twisted donor-acceptor-type electroactive bipolar derivatives using benzophenone and bicarbazole as building blocks. Derivatives were synthesized through the reaction of 4-fluorobenzophenone with various mono-alkylated 3,3'-bicarbazoles. We have provided a comprehensive structural characterization of these compounds. The new materials are amorphous and exhibit suitable glass transition temperatures ranging from 57 to 102 °C. They also demonstrate high thermal stability, with decomposition temperatures reaching 400 °C. The developed compounds exhibit elevated photoluminescence quantum yields (PLQY) of up to 75.5% and favourable HOMO-LUMO levels, along with suitable triplet-singlet state energy values. Due to their good solubility and suitable film-forming properties, all the compounds were evaluated as blue TADF emitters dispersed in commercial 4,4'-bis(N-carbazolyl)-1,10-biphenyl (CBP) host material and used for the formation of emissive layer of organic light-emitting diodes (OLEDs) in concentration-dependent experiments. Out of these experiments, the OLED with 15 wt% of the emitting derivative 4-(9'-{2-ethylhexyl}-[3,3']-bicarbazol-9-yl)benzophenone exhibited superior performance. It attained a maximum brightness of 3581 cd/m2, a current efficacy of 5.7 cd/A, a power efficacy of 4.1 lm/W, and an external quantum efficacy of 2.7%.

Utilization of natural dyes extracted from mustard flower (Genus: Brassica, Species: Napus) as photosensitizer for DSSC: Experimental and computational studies

Dye-sensitized solar cells (DSSC) are considered as one of the most promising photovoltaic technologies, while exploring alternatives to traditional silicon-based solar cells. Dye sensitizer is a very important component of DSSC and the use of natural dyes in these cells is a promising development for this technology, as it has non-hazardous impact on the environment. This work reports the new natural dye extracted from Brassica Napus flower petals and used as sensitizer in TiO2 based DSSC. UV–Vis spectra showed the presence of carotenoid and flavonoid pigments along with broad absorption in dye loaded TiO2. FITR revealed functional groups in the Brassica Napus dye extract. Mass spectroscopy was used to find major constituents present in extract. With the natural Brassica Napus sensitizer and TiO2, photovoltaic performance results viz. conversion efficiency (ɳ%) 0.062, short circuit current density (Jsc) 0.45 mA/cm2, open circuit voltage (Voc) 0.260 V and fill factor (FF) 0.52 were observed. Further, HOMO-LUMO levels of constituents present in Brassica Napus have been measured via CV measurements and compared with relative energetic obtained by computational studies. The transport characteristics revealed from EIS studies were used to rationalize the observed photo-voltaic performance of the DSSC.

“Novel Magneson-I derived λ-shaped tris azo liquid crystalline trimers”

One new homologous series of liquid crystalline λ-shaped tris azo trimers containing azobenzene moiety as a rigid core and ether linkages were synthesized by the reaction of various n-butylazobenzene having bromoalkoxy tail with magneson-I dye respectively. Their right structure was confirmed by FT-IR, 1H NMR, 13C NMR spectroscopy, mass spectrometry and elemental analysis. On the polarising optical microscope (POM), their thermotropic properties were examined, and additional studies were conducted using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). All the trimers with an even number of flexible spacers (n = 2 and 4) show excellent liquid crystalline properties as an enantiotropic nematic phase with greater mesophase length and good thermal stability. The introduction of odd-membered methylene disrupts the orderly stacking of layers and results in a change in mesogenic behaviour. Their structure-property relationships, the influence of different flexible spacers, the mesophase ranges and the photo-isomerisation of liquid crystalline trimers were described. A view of their photochromic behaviour was gained by UV–Visible spectroscopy. The 6-31G (d, p) basis set is combined with the B3LYP functional, which is used for computational studies of λ-shaped tris azo trimers. This approach allows for the determination of various quantum mechanical descriptors that can help us comprehend the mesogenic nature of molecules in computational studies. The results of the Gaussian calculation showed that the target compounds have low energy differences between HOMO-LUMO levels and good chemical reactivity. The examination of ESP and optical characteristics also yielded important information about the electronic structure and potential uses of these compounds.

(Invited) Conjugated Metallophthalocyanine as Hole-Transporting Materials for Improved Stability in Perovskite Solar Cells

Perovskite solar cells (PSCs) are promising candidates to reach the market to complement the current offer of photovoltaic cells although for such a thing they still have to overcome some challenges such as long-term stability. The hole transporting layer (HTL) is a crucial component in n-i-p PSC, since it must favor an adequate movement of charges and protect the perovskite layer from environmental conditions. In this sense, the commonly used HTL, spiro-OMeTAD, does not provide PSCs with sufficient stability and is too expensive. Cheaper molecular materials such as metallophthalocyanines are proving to be a good alternative, as they provide greater stability.[1]In this communication, we will present the synthesis of novel ZnPcs and CuPcsmonomers [2] and ZnPc dimers [3] (see as examples Figure 1) as efficient, stable, and low cost HTMs in PSCs. The MPcs are substituted with functional groups that possesses a very good solubility in a wide range of organic solvents, adequate HOMO LUMO levels and thus can be applied from solution processing in a wide range of perovskite solar cell devices.

Non-Fullerene Acceptors for Organic Photovoltaics

Non-fullerene acceptors (NFA) have attracted much attention in organic photovoltaics because of their excellent light-harvesting property and facile tuning of HOMO-LUMO levels. In particular, ITIC and Y6 type NFAs have exhibited very high power conversion efficiency exceeding 15%. In this talk I will give an overview of our initiatives on NFAs.[1] T. Umeyama, K. Igarashi, D. Sasada, Y. Tamai, K. Ishida, T. Koganezawa, S. Ohtani, K. Tanaka, H. Ohkita, H. Imahori, Chem. Sci., 11, 3250-3257 (2020).[2] T. Umeyama, K. Igarashi, D. Sasada, K. Ishida,T. Koganezawa, S. Ohtani, K. Tanaka, H. Imahori, ACS Appl. Mater. Interfaces, 12, 39236-39244 (2020).[3] T. Umeyama, K. Igarashi, Y. Tamai, T. Wada, T. Takeyama, D. Sasada, K. Ishida, T. Koganezawa, S. Ohtani, K. Tanaka, H. Ohkita, H. Imahori, Sus. Energy Fuels, 5, 2028-2035 (2021).[4] T. Umeyama, T. Wada, K. Igarashi, K. Kato, A. Yamakata, T. Takeyama, Y. Sakamoto, Y. Tamai, H. Ohkita, K. Ishida, T. Koganezawa, S. Ohtani, K. Tanaka, H. Imahori, ACS Appl. Energy Mater., 4, 14022-14033 (2021).[5] S. Li, R. Nishikubo, T. Wada, T. Umeyama, H. Imahori, A. Saeki, Polymer J., in press.

A π‐Extension Process from 9‐Phosphaanthracene Leading to Phosphatetraphenes and Phosphatetracenes

AbstractExtension of π‐system with phosphinine (phosphorine, phosphabenzene) has been of interest because of the expected higher HOMO and lower LUMO levels compared with the corresponding carbon congeners. In this paper, a π‐extension process based on the 9‐phosphaanthracene skeleton was demonstrated by synthesizing 12‐phosphatetraphene and 9‐phosphabenzo[f]tetraphene by utilizing the deaminative aromatization pathway. Starting from 3,5‐bis(trifluoromethyl)aniline, we developed the dibromotriarylmethane precursors containing the 3,5‐bis(trifluoromethyl)‐2‐bromophenyl unit, which would be slightly effective to increase the steric congestion around the fragile P=C bonds incorporated in the fused polyaromatic skeletons. The bis‐trifluoromethyl 12‐phosphatetraphenes have been synthesized together with the mono‐trifluoromethyl derivative, and the planar 12‐phosphatetraphene skeleton was confirmed. On the other hand, the CF3‐substituted 9‐phosphabenzo[f]tetraphene displayed a remarkably twisted fused five ring system leading to the wavy structures incorporating phosphinine. Also, synthetic study of 5‐phosphatetracene using the bis(trifluoromethyl)phenyl unit was attempted and the incomplete elimination of the amine indicated labile characters of the observed phosphorus congener of tetracene. The findings of this study would be informative for developing heavier congeners of polyaromatic hydrocarbons (PAHs) as well as the trifluromethyl effects.

Design, DFT and molecular doping studies of metal complexes as a neurotransmitter modulator of autism spectrum disease in preschool children

Coordination of transition metals with pyrazolines has formed complexes of cobalt(II), nickel(II), copper(II) and zinc(II) utilizing new pyrazoline ligand 3-(2-pyrollyl)-5-(4-bromophenyl)-1-carbomathyl-2-pyrazoline (L). The ligand was synthesized by Micheal addition of chalcone (E)-3-(4-bromophenyl)-1-(1H-pyrrol-2-yl)prop-2-en-1-one with excess 4-methylthio-semicarbazide. The metal complexes were isolated using the thin layer chromatography technique and synthesized and characterized based on elemental analyses (C, H, N, and S), IR, UV–visible spectra, thermal analyses,1H-and13C-NMRspectra, molar conductivity and magnetic susceptibility measurements. The results indicated a tetrahedral geometry around the zinc(II) complex and octahedral environments around the copper(II), nickel(II) and cobalt(II) complexes. The density function theory of 2-pyrazoline, L, and its metal complexes showed agreement in the gap energies between HOMO–LUMO levels. The bond lengths (Zn–S) and (Zn–Cl) were less than ones of Ni–S, Co–S and Cu–S. The density functional theory calculations were used to investigate geometry optimization, natural bond orbital analysis, and molecular electrostatic potential maps of the synthesized ligand and its complexes. Additionally, time-dependent density function theory calculations were performed to study their electronic structures. The effect of those complexes on the neurotransmitter GABA offers potential insights into new therapeutic mechanisms. This method relies on coordination to a heterocyclic molecule like pyrazoline to release the excess metal ions.