Hexyloxy Chains Research Articles

Dopant-Free Hole Transport Material Based on Non-Covalent Interaction for Efficient Perovskite Solar Cells.

Hole transport materials (HTMs) have a critical impact on the performance of perovskite solar cells (PSCs). Especially, the dopant-free HTMs could avoid the usage of hygroscopic dopants and reduce costs, which are important for device stability. Most of the current organic dopant-free HTMs are polycyclic aromatic hydrocarbons-based planar conjugated structures. Yet, the synthesis of conjugated fused heterocycles is often complicated. In this work, intramolecular non-covalent interaction is introduced to construct two organic HTMs (DCT and DTC), which can be facilely obtained through simple reactions. Compared to DTC with hexyl chain on the central benzene ring, DCT with hexyloxy chains shows better planarity in the core structure, as a result of the intramolecular non-covalent interactions between oxygen on hexyloxy and sulfur atom on the adjacent thiophene, as reflected from its single crystal structure. Moreover, DCT in a pristine state shows a decent hole mobility comparable to the doped Spiro-OMeTAD. Ultimately, conventional devices using dopant-free DCT as HTM show a high efficiency of 22.50%, with excellent long-term stability, and light and thermal stability. The results show that the noncovalent interaction is a useful and simple design strategy for dopant-free HTMs, that can effectively improve the efficiency and stability of PSCs.

Biphenyl based schiff base derivatives of 6-aminocoumarin: Design, synthesis, mesomorphic properties and DFT studies

The study focused on synthesizing two series of coumarin Schiff base liquid crystals. These series involved molecules with variations in alkoxy chains at aldehyde ends: one being the Schiff base with 4′‑hydroxy-[1,1′]-biphenyl-4-carbaldehyde (ASBP series) and the other being alkyl 4-formyl-[1,1′]-biphenyl-4-carboxylate (AEBP series). The compounds were characterized using FTIR, NMR, and Mass spectral analyses. All the compounds were studied for their mesomorphic properties, differential scanning calorimetry (DSC) and polarized optical microscopy (POM). In both the homologous series, variation of alkyl chain length showed intriguing phase transitions. In the first homologous series ASBP, compound with hexyloxy chain displayed an enantiotropic nematic (N) phase, while those with chain lengths n = 8–16 exhibited enantiotropic smectic A (SmA) mesophase. Similarly, in the AEBP series, compounds with n = 6,8 chain length showed an enantiotropic nematic (N) phase, while those with higher chain lengths n = 10–16 exhibited enantiotropic smectic A (SmA) phases. SmA mesophase was further confirmed by powdered XRD analysis. The study included DFT theoretical calculations to comprehend the compounds' mesomorphic behavior, comparing them with analogous reported compounds. Additionally, the investigation correlated experimental findings of individual compounds with calculated parameters like polarizability, dipole moment, and aspect ratio. Molecular electrostatic potential projections and analysis of frontier molecular orbitals were also employed to elucidate how polarity variations in terminal chains and mesogenic cores influenced the energy gap of FMOs and the distribution of electrostatic charges on these compounds. It has been found that the ASBP series has lower energy gap and higher dipole moment than the AEBP series.

Non-covalent Electrostatic Interactions between Calix[4]arenes and Porphyrins using UV-VIS Spectroscopy

Different calix[4]arenes and cationic porphyrins were synthesized under suitable conditions. Electrostatic interactions between these cationic and anionic species were investigated using ultraviolet-visible spectroscopy spectroscopic techniques. A high thermodynamic stability was found between non-covalent calix[4]arenes capped porphyrins and the stability of the system retained even after addition of the electrolyte. The Job?s Plot revealed that the complex follows a 1:1 stoichiometry, giving the best binding interaction when the host calix[4]arene is non-substituted. The hexyloxy chain appended at the lower rim of the calix[4]arenes for stabilizing its cone confirmation results into less binding with cationic porphyrins.. KEYWORDS :Calix[4]arenes, Electrostatic interactions, Host-guest interactions, Porphyrins, Supramolecular chemistry, Ultraviolet-visible spectroscopy.

Molecular Conformations of Shape Anisometrically Variant Mesogens in Liquid Crystalline Phase Studied by 13C NMR Spectroscopy.

Mesogens that vary in shape anisometry have been investigated by 13C solid-state NMR in the liquid crystalline phase to inspect the conformations. The molecules examined comprise of (i) rod-like mesogen with three-phenyl ring core and terminal hexyloxy chains, (ii) three-ring core linked to the fourth phenyl ring via a spacer, and (iii) trimesic acid connected to three side arms core units through a spacer. The order parameter (Szz) values for the phenyl rings of the rod-like mesogen are 0.65-0.68, while the mesogen with a three-ring core linked to a phenyl ring via spacer showed dissimilarity. Consequently, for the core unit's phenyl rings, Szz is ~ 0.70, and the terminal phenyl ring showed a low value of 0.12. For the trimesic acid based mesogen, the Szz value for the side arm phenyl rings is ~ 0.53, and for the central phenyl ring, a very low value of 0.11 is witnessed. By considering the ordering of the rod-like mesogen as a yardstick and employing the ratios of Szz values of the phenyl rings, the average conformations of other mesogens are arrived. Accordingly, for the trimesic acid based mesogen, a tripod-like conformation instead of l shape is proposed in the liquid crystalline phase.

D-π-A Structured Porphyrin and Organic Dyes with Easily Synthesizable Donor Units for Low-Cost and Efficient Dye-Sensitized Solar Cells.

This study aimed to develop low-cost D-π-A structured porphyrin and organic dyes with easily synthesizable donor units instead of the conventional complex multistep synthetic donor unit of Hexyloxy-BPFA [bis(7-(2,4-bis(hexyloxy)phenyl)-9,9-dimethyl-9H-fluoren-2-yl)amine] used in SGT-021 and SGT-149 as well-known record cosensitizers with an extremely high power conversion efficiency (PCE). The design strategy concerned the easier synthesis of low-cost donor units with inversion structures in donor groups via donor structural engineering, particularly by changing the position of the fluorene and phenylene units in the donor moiety while keeping the π-bridge and acceptor unit unchanged, leading to the synthesis of two D-π-A structured porphyrins [SGT-021(D0) and SGT-021(D)] and one D-π-A structured organic sensitizer [SGT-149(D)] for dye-sensitized solar cells (DSSCs). Specifically, porphyrin SGT-021(D0) incorporated two hexyl chains into the 9-position of each fluorene, while SGT-021(D) and SGT-149(D) substituted two hexyloxy chain units to the terminal position of each fluorene in the donor groups of porphyrin dyes. The effect of the position of the fluorene and phenylene units in the donor moiety on the photochemical and electrochemical properties, as well as the photovoltaic performance, was compared with the reference dyes of SGT-021 and SGT-149, previously reported by the research group. After optimizing the DSSC devices, SGT-021(D) and SGT-021(D0) achieved a high PCE of 11.6 and 10.5%, respectively, while SGT-149(D) exhibited a little lower PCE of 10.3% under the standard AM 1.5G light intensity. The cell performance of DSSC devices based on SGT-021(D) and SGT-149(D) was inferior to the corresponding reference dyes of SGT-021 and SGT-149 due to their lower donating ability of Hexyloxy-BPFA than Hexyloxy-BFPA.

Hydrogen-bonding stabilized columnar mesophases in hexasubstituted triphenylene 2,3-Dicarboxamides

A series of new mixed tail triphenylene derivatives having four β-alkoxy and two adjacent β-carboxamide side chains have been prepared and characterized. The synthesis was carried out by amidation of the triphenylene 2,3-dicarboxylic methyl ester with various primary amine. All the dicarboxamides exhibit an enantiotropic Colh phase, except compound TPC6-(CONHC6H13)2 bearing the shortest hexyloxy chains. Effects of variation in lengths of alkoxy and N-alkyl chains on mesogens were also studied and the pronounced influence of lengths of alkoxy chains turned out to be more important than that of N-alkyl chains. Furthermore, the intermolecular hydrogen bonding induced by amide functions in TPC8-(CONHC4H9)2 does indeed enhance the mesophase stability in comparison to the non-hydrogen bonding ester TPC8-(COOC4H9)2, as reflected by higher clearing temperatures and evidenced by temperature-dependent FT-IR studies. Although the compound TPC6-(CONHC6H13)2 was found to decompose to imide compound on the hot stage before clearing in the course of the POM experiment, only it shows good gelation property in single toluene, indicating that the intermolecular hydrogen bonding is not the only factor responsible for the formation of gel in these molecules.

Crystal structure of 8-hex-yloxy-2-[(Z)-2-(naph-thal-en-2-yl)ethen-yl]quinoline.

In the title mol-ecule, C27H27NO, the naphthalene and quinoline groups are both planar and subtend a dihedral angle of 15.47 (7)°. They are nearly coplanar with the cis-vinyl bridge and the hex-yloxy chain, which adopts an all-trans conformation, resulting in transannular bifurcated intra-molecular C-H⋯N,O contact. The crystal structure features γ-packing of the aromatic moieties, while the parallel packing of alkyl chains resembles that of alkanes.

Theoretical assessments and optical and electrochemical properties of the alkoxylated bischalcone as emissive material in single-layer OLED.

A new bischalcone comprising of hexyloxy (-OC6H2n+1) chain based on 'Donor (D)-π-Donor (D)' system was successfully designed and synthesized to demonstrate as emitting material for single-layer OLEDs. Density functional theory (DFT) assessment at B3LYP/6-31G(d,p) was computed to obtain frontier molecular orbitals (FMOs), chemical reactivity and molecular electrostatic potential (MEP). The utilization of alkoxy substructure towards the chalcone moiety has increased the solubility and contributed to HOMO-LUMO gap energy level 3.473eV by UV-Vis spectroscopy and was found to have good agreement with the theoretical calculations. The investigations on their optical, electrochemical and thermal behaviour also were conducted via UV-Vis, cyclic voltammetry (CV), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The entitled alkoxylated bischalcone (CSAB) revealed good thermal stability up to 300°C and showed high glass transition temperatures. At positive potential, a quasi-reversible oxidation (Eox 1/2) peak at 2.40V and negative potentials exhibited reduction peak at 0.78V, respectively. The application of CSAB was tested in the form of thin film in respect to its conductivity in terms of electrical current and electroluminescence behaviour. It gave an intense yellow emission which has provided depth fundamental understanding on its potentiality featuring alkoxylated bischalcone moiety as solution-processed OLED material in optoelectronic interests.

A New Dimeric Copper(II) Complex of Hexyl Bis(pyrazolyl)acetate Ligand as an Efficient Catalyst for Allylic Oxidations.

A new dimeric copper(II) bromide complex, [Cu(LOHex)Br(μ-Br)]2 (1), was prepared by a reaction of CuBr2 with the hexyl bis(pyrazol-1-yl)acetate ligand (LOHex) in acetonitrile solution and fully characterized in the solid state and in solution. The crystal structure of 1 was also determined: the complex is interlinked by two bridging bromide ligands and possesses terminal bromide ligands on each copper atom. The two pyrazolyl ligands in 1 coordinate with the nitrogen atoms to complete the Cu coordination sphere, resulting in a five-coordinated geometry—away from idealized trigonal bipyramidal and square pyramidal geometries—which can better be described as distorted square pyramidal, as measured by the τ and χ structural parameters. The pendant hexyloxy chain is disordered over two arrangements, with final site occupancies refined to 0.705 and 0.295. The newly synthesized complex was evaluated as a catalyst in copper-catalyzed C–H oxidation for allylic functionalization through a Kharasch–Sosnovsky reaction without any external reducing agent. Using 0.5 mol% of this catalyst, and tert-butyl peroxybenzoate (Luperox) as an oxidant, allylic benzoates were obtained with up to 90% yield. The general reaction time was only slightly decreased to 24 h but a very significant decrease in the alkene:Luperox ratio to 3:1 was achieved. These factors show relevant improvements with respect to classical Kharasch–Sosnovsky reactions in terms of rate and amount of reagents. The present study highlights the potential of copper(II) complexes containing functionalized bis(pyrazol-1-yl)acetate ligands as efficient catalysts for allylic oxidations.

Azobenzene-based polycatenars: Investigation on photo switching properties and optical storage devices

We report the photo switching behaviour of azobenzene-based rod-like polycatenar molecules having three hexyloxy chains at one terminus and a variable chain at the other terminus. The latter was varied with OC6H13, SC6H13, C7H13, OC10H21 and O(CH2)4C6F13 chains. All molecules are liquid crystalline exhibiting wide ranges of nematic phases with cybotactic clusters in addition to Smectic C phase. The effect of variation of terminal chains on the photo-switching properties of the above series of azo compounds upon light irradiation and their kinetic reactions are presented. Surprisingly, trans-cis conversion in solutions takes around 85 s, while relaxing back i.e. cis-trans conversion takes ~30–60 min depending on the type of the terminal chain. On the other hand, irrespective of the nature of the terminal chain all of them exhibit fast thermal back relaxation time. A possible reason for the observed phenomena is presented based on a caterpillar model. Moreover, the potential of one selected example in optical storage device is elucidated. Therefore, this work shows the structure-property relationship in such type of polycatenar molecules related to their photo switching properties.

Phase behaviour of alkynyl-terminated bicyclo[3.3.0]octa-1,4-diene ligands: a serendipitous discovery of novel calamitic liquid crystals

ABSTRACT Chiral bicyclo[3.3.0]octadienes carrying two alkoxy- or alkynyloxy side chains are highly valuable ligands for asymmetric catalysis but have never been explored regarding their liquid crystalline self-assembly. Therefore, a series of bicyclo[3.3.0]octadienes was synthesised and studied by differential scanning calorimetry (DSC), polarising optical microscopy (POM) and X-ray diffraction (XRD) to understand the role of the terminal alkyne unit in the side chain. Dienes with hexinyloxy or octinyloxy side chains behaved similar to the diene with hexyloxy chains, showing broad SmA phases and a pronounced tendency for supercooling. In contrast, dienes with mono- or diethylenglycolpropargylic ether chains displayed a decreased phase range and monotropic behaviour in the latter case, while the corresponding diene with propargylether side chains was non-mesomorphic.

Properties and structural coloured film preparation of some chiral dopants derived from D-Isosorbide

A series of chiral dopants derived from D-isosorbide were synthesized. Some of them exhibita monotropicsmecticA phase. Comparison of the melting points of these chiral dopants, the decrease of them is mainly driven by the large entropy change. The helical twisting power (HTP) values of these chiral dopants with branched alkyl chains, lateral fluoro-substituents and double bonds are lower than those of the chiral dopants with hexyloxy chains. Structural colored polymer films with a right-handed helix are prepared using these chiral dopants.

A Fully Non‐fused Ring Acceptor with Planar Backbone and Near‐IR Absorption for High Performance Polymer Solar Cells

AbstractFused‐ring electron acceptors have made significant progress in recent years, while the development of fully non‐fused ring acceptors has been unsatisfactory. Here, two fully non‐fused ring acceptors, o‐4TBC‐2F and m‐4TBC‐2F, were designed and synthesized. By regulating the location of the hexyloxy chains, o‐4TBC‐2F formed planar backbones, while m‐4TBC‐2F displayed a twisted backbone. Additionally, the o‐4TBC‐2F film showed a markedly red‐shifted absorption after thermal annealing, which indicated the formation of J‐aggregates. For fabrication of organic solar cells (OSCs), PBDB‐T was used as a donor and blended with the two acceptors. The o‐4TBC‐2F‐based blend films displayed higher charge mobilities, lower energy loss and a higher power conversion efficiency (PCE). The optimized devices based on o‐4TBC‐2F gave a PCE of 10.26 %, which was much higher than those based on m‐4TBC‐2F at 2.63 %, and it is one of the highest reported PCE values for fully non‐fused ring electron acceptors.

A Fully Non-fused Ring Acceptor with Planar Backbone and Near-IR Absorption for High Performance Polymer Solar Cells.

Fused-ring electron acceptors have made significant progress in recent years, while the development of fully non-fused ring acceptors has been unsatisfactory. Here, two fully non-fused ring acceptors, o-4TBC-2F and m-4TBC-2F, were designed and synthesized. By regulating the location of the hexyloxy chains, o-4TBC-2F formed planar backbones, while m-4TBC-2F displayed a twisted backbone. Additionally, the o-4TBC-2F film showed a markedly red-shifted absorption after thermal annealing, which indicated the formation of J-aggregates. For fabrication of organic solar cells (OSCs), PBDB-T was used as a donor and blended with the two acceptors. The o-4TBC-2F-based blend films displayed higher charge mobilities, lower energy loss and a higher power conversion efficiency (PCE). The optimized devices based on o-4TBC-2F gave a PCE of 10.26 %, which was much higher than those based on m-4TBC-2F at 2.63 %, and it is one of the highest reported PCE values for fully non-fused ring electron acceptors.

Effect of triphenylethylene analogues on the performance of carbazole-based dye-sensitized solar cells

Three metal-free organic dyes JY60-62 based on triphenylethylene (TPE)-decorated carbazole have been synthesized and applied as photosensitizers in dye-sensitized solar cells. In comparison to TPE-free dye CVHTC, the anti π-π stacking characteristic stemming from the introduced TPE units helps JY60-62 to decrease the excited-state self-quenching in aggregation state and thus get better photovoltaic performance. Efforts on suppressing the unfavorable charge recombination by embellishing TPE with long hexyloxy chains (JY61), and facilitating the intramolecular charge transfer effect by improving the molecular planarity via the replacement of TPE's near-carbazole phenyl group with thiophene (JY62) seem not effective as expected, although slightly enhanced open-circuit voltage of JY61-based devices and short-circuit current density of JY62-based devices have been observed. Finally, the non-modified TPE-involved dye JY60 achieved the highest power conversion efficiency of 6.40%, exceeding approximate 30% of TPE-free dye CVHTC. These results reveal that original TPE unit without further redundant modification could work as an ideal building block for improving the photovoltaic properties of conventional easy-stacking dyes.

Effects of introducing functional groups on the performance of phenoxazine-based dye-sensitized solar cells

Phenoxazine dyes with a hexyloxy chain and furan moiety were synthesized and used in dye-sensitized solar cells. The dyes were designed to investigate the effects of these substituents on the photophysical and electrochemical properties of the dyes and on cell photovoltaic performance. The introduced hexyloxy moiety, as an additional donor, improved the short-circuit current and open-circuit voltage of the cell by increasing light absorption and steric hindrance, respectively. The furan moiety introduced in the phenoxazine dye as a bridge unit led to a bathochromic shift of the absorption band and a large amount of dye adsorption, increasing the short-circuit current of the cell. Among the synthesized dyes, those with the furan moiety showed the best conversion efficiency of 6.34%.

Triphenylene-Imidazolium Salts and Their NHC Metal Complexes, Materials with Segregated Multicolumnar Mesophases.

Two imidazolium salts containing one or two pentadodecyloxytriphenylene units linked through a hexyloxy chain and Br-, [AuBr mCl4- m]-, or [PtBr mCl4- m]2- ( m = 0-3) as counterion have been prepared. Reaction of the imidazolium bromides with M2O (M = Cu, Ag), or carbene transmetalation from the silver product, leads to N-heterocyclic carbene complexes [MX(NHC)] (M = Cu, X = Br; M = Au, X = Cl, C≡CPh), [Ag(NHC)2][AgBr2], and [PtCl2(NHC)2], with NHC bearing one or two triphenylene fragments. Except for the gold derivatives and one Cu complex, the rest of them behave as liquid crystals organized in columnar mesophases (rectangular c2 mm or p2mg or hexagonal p6mm symmetries) with melting points in the range 30 to 60 °C and clearing points in the range 57-112 °C. The mesophase structures were determined by small-angle X-ray scattering. Structural studies and models point to nanosegregation of triphenylene columns and imidazolium/metal carbene moieties, separated by alkoxy chains, leading to multicolumnar systems. The compounds display emission spectra related to the triphenylene core in solution, in the mesophase, in the isotropic liquid, and in the solid state.

Octahedral [Pd6 L8 ]12+ Metallosupramolecular Cages: Synthesis, Structures and Guest-Encapsulation Studies.

Four planar tripyridyl ligands (Ltripy ), 1,3,5-tris(pyridin-3-ylethynyl)benzene 1 a, 1,3,5-tris[4-(3-pyridyl)phenyl]benzene 2 a, and the hexyloxy chain functionalized derivatives 1,3,5-tris[(3-hexyloxy-5-pyridyl)ethynyl]benzene 1 b, and 1,3,5-tris[4-(3-hexyloxy-5-pyridyl)phenyl]benzene 2 b, were synthesized and used to generate a family of [Pd6 (Ltripy )8 ](BF4 )12 octahedral cages (Ltripy =1 a, b or 2 a, b). The ligands and cages were characterized using a combination of 1 H, 13 C, and DOSY nuclear magnetic resonance (NMR) spectroscopy, high resolution electrospray mass spectrometry (HR-ESI-MS), infrared (IR) spectroscopy, elemental analysis, and in three cases, X-ray crystallography. The molecular recognition properties of the cages with neutral and anionic guests were examined, in dimethyl sulfoxide (DMSO), using NMR spectroscopy, mass spectrometry and molecular modeling. No binding was observed with simple aliphatic and aromatic guest molecules. However, anionic sulfonates were found to interact with the octahedral cages and the binding interaction was size selective. The smaller [Pd6 (1 a, b)8 ]12+ cages were able to interact with three p-toluenesulfonate guest molecules while the larger [Pd6 (2 a, b)8 ]12+ systems could host four of the anionic guest molecules. To probe the importance of the hydrophobic effect, a mixed water-DMSO (1:1) solvent system was used to reexamine the binding of the neutral organic guests adamantane, anthracene, pyrene and 1,8-naphthalimide within the cages. In this solvent system all the guests except adamantane were observed to bind within the cavities of the cages. NMR spectroscopy and molecular modeling indicated that the cages bind multiple copies of the individual guests (between 3-6 guest molecules per cage).

Enhancement of the photovoltaic performance in D3A porphyrin-based DSCs by incorporating an electron withdrawing triazole spacer

In this study, we report the preparation of two novel zinc-porphyrin derivatives (ZnP-3DoH-click-CNCOOH and ZnP-3DoH-click-COOH) and two reference compounds (ZnP-3DoH-CNCOOH and ZnP-3DoH-COOH) as sensitizers in dye-sensitized solar cells (DSCs). The photo-physical and electrochemical measurements along with the computational studies suggest that the four synthesized porphyrin derivatives exhibit appropriate light absorption characteristics as well as suitable molecular orbital levels for their use as sensitizers in DSCs. All the modified zinc-porphyrin complexes bear hexyloxy chains at the ortho-positions of their three phenyl rings and contain either a carboxylic or a cyanoacrylic acid as anchoring group. In the zinc-porphyrin derivatives ZnP-3DoH-click-CNCOOH and ZnP-3DoH-click-COOH, a spacer with an electron withdrawing unit was incorporated between the porphyrin ring and each anchoring group. More specifically, the triazole ring was used as a spacer since it is considered to be a highly efficient electron transfer bridge. In addition, the pentafluoro-phenyl ring was selected due to its strong electron withdrawing ability in both final derivatives (ZnP-3DoH-click-CNCOOH and ZnP-3DoH-click-COOH). Following this strategy, fourfold and eightfold increase of the device performance was observed regarding ZnP-3DoH-click-CNCOOH and ZnP-3DoH-click-COOH, respectively, when compared to the efficiencies achieved with the reference compounds (ZnP-3DoH-COOH and ZnP-3DoH-CNCOOH). A more detailed interpretation of the charge dynamics in these devices was carried out using charge extraction (CE) and open-circuit voltage decay (OCVD) measurements.

Structure-Photoproperties Relationship Investigation of the Singlet Oxygen Formation in Porphyrin-Fullerene Dyads.

A systematic structure-photoproperties relationship study of the interactions of porphyrin-fullerene dyads with molecular oxygen was conducted on a set of three porphyrin-fullerene dyads, as this approach of related applications - oxygen sensitivity and photo-induced singlet oxygen generation - of such dyads remained to be endeavoured. To promote energy transfers between the porphyrin and fullerene units and limit undesired charge separation, a particular attention was devoted to the choice of the solvents for the photoproperties determination. Toluene, in which in addition the compounds investigated are not aggregated, was selected accordingly. The molecular orbital levels and energy gaps of the dyads were determined by electrochemistry and theoretical calculations. Their ground state absorption, steady-state fluorescence-based oxygen sensitivity and photo-induced singlet oxygen generation were determined. The dyads were designed to benefit from a facilitated synthetic porphyrin-fullerene coupling thanks to an easy access to formyl-functionalized porphyrins. The effect of two structural parameters was investigated: the presence of electron-donating hexyloxy chains at the para position of the meso-phenyl, and the presence of a phenylacetylene spacer. This latest factor appeared to have the most predominant effect on all these properties.