Position Of Heteroatom Research Articles

Isomer engineering for deep understanding of aggregation-induced photothermal enhancement in conjugated systems.

Organic photothermal materials based on conjugated structures have significant potential applications in areas such as biomedical diagnosis, therapy, and energy conversion. Improving their photothermal conversion efficiency through molecular design is critical to promote their practical applications. Especially in similar structures, understanding how the position of heteroatoms affects the conversion efficiency is highly desirable. Herein, we prepared two isomeric small D-A molecules with different sulfur atom positions (TBP-MPA and i-TBP-MPA), which display strong and broad absorption in the UV-visible region due to their strong intramolecular charge transfer characteristics. Compared to i-TBP-MPA, TBP-MPA demonstrates aggregation-induced photothermal enhancement (AIPE). Under simulated sunlight (1 kW m-2) irradiation, the stable temperature of TBP-MPA powder reached 60 °C, significantly higher than the 50 °C achieved by i-TBP-MPA. Experimental and theoretical results indicate that the S⋯N non-covalent interactions in TBP-MPA impart a more rigid conjugated framework to the molecule, inducing ordered molecular stacking during aggregation. This ordered stacking provides additional non-radiative transition channels between TBP-MPA molecules, enhancing their photothermal performance in the aggregated state. Under 1 sun irradiation, TBP-MPA achieved a water evaporation rate of 1.0 kg m-2 h-1, surpassing i-TBP-MPA's rate of 0.92 kg m-2 h-1.

Identification of the optimal doping position of hetero-atoms in chalcogen-doped Fe–N–C catalysts for oxygen reduction reaction

The excellent oxygen reduction reaction (ORR) activity of Fe–N–C catalysts in acidic media makes them potential for low-cost proton exchange membrane fuel cells. In recent years, it has been shown that heteroatoms (B, O, S, P, Cl, F, etc.) can be used as electron-withdrawing groups to modulate the planar structure and electron distribution of the Fe–Nx active sites to achieve simultaneous improvement of catalytic activity and stability. However, the optimal location of the heteroatoms remains unclear. Here, taking chalcogen heteroatoms (S and Se) as an example, we control the doping positions and investigate their effect on the ORR performance of the Fe–N–C catalysts. The first coordination shell of the iron single atom is identified as the optimal doping position. The optimized catalyst Fe–N3S1/NC and Fe–N3Se1/NC demonstrate improved activity and stability in both half cells and fuel cells. This work provides insights into the enhancement mechanism of heteroatom doping of single-atom catalysts.

Electron-transporting boron-doped polycyclic aromatic hydrocarbons: Facile synthesis and heteroatom doping positions-modulated optoelectronic properties

While heteroatom doping serves as a powerful strategy for devising novel polycyclic aromatic hydrocarbons (PAHs), the further fine-tuning of optoelectronic properties via the precisely altering of doping patterns remains a challenge. Herein, by changing the doping positions of heteroatoms in a diindenopyrene skeleton, we report two isomeric boron, sulfur-embedded PAHs, named Anti-B2S2 and Syn-B2S2, as electron transporting semiconductors. Detailed structure-property relationship studies revealed that the varied heteroatom positions not only change their physicochemical properties, but also largely affect their solid-state packing modes and Lewis base-triggered photophysical responses. With their low-lying frontier molecular orbital levels, n-type characteristics with electron mobilities up to 1.5 × 10−3 cm2 V−1 s−1 were achieved in solution-processed organic field-effect transistors. Our work revealed the critical role of controlling heteroatom doping patterns for designing advanced PAHs.

Polarization Reorientation of Carbon Nitride Induced by a Local Bridge Donor for Boosting Photocatalytic H2 Evolution Integrated with Selective Amine Oxidation

Polymeric carbon nitride (PCN) has attracted much attention in the field of photocatalysis, but the use of PCN is often confined to internal structures with highly symmetrical heptazine units bridged by N atoms. Accurate tuning of the positions of heteronuclear atoms is a meaningful strategy but remains a big challenge. Herein, a catalyst with P═N bonds accurately embedded among the heptazine units was prepared using a straightforward polymerization method. According to density functional theory simulation and experimental data, the embedded P═N chains act as donor units that cause a profound redistribution of the symmetric electron cloud density of heptazine, which significantly promotes local charge polarization and leads to a strong built-in electric field. The consequence is enhanced exciton dissociation, charge separation, and surface activation. In the photocatalytic oxidation of benzylamine over the optimized PCN under visible light irradiation without the use of a solvent and co-catalyst, the hydrogen production rate is 388 μmol·g–1·h–1 and the selectivity to N-benzylidenebenzylamine is >99%. In this paper, we propose a tractable strategy to precisely tune the position of heteroatoms, providing an efficient catalyst for hydrogen production together with the simultaneous generation of value-added imines.

Investigating multifaceted action of ibuprofen derivatives towards cox isozymes and interleukin-6 (IL-6) site correlating with various target sites

The multifaceted action of new ibuprofen analogs has been investigated against inflammation, neurological and pro-inflammation factors. On the basis of ADMET (absorption, distribution, metabolism, excretion, and toxicity) analysis, molecular docking as well as molecular dynamics simulation, compound 3 was thought to have good anti-inflammatory activity. As the presence of structural interactions such as conventional hydrogen bonds and electrostatic interactions through the nitrogen atoms of the linker in compound 3 gave strong evidence of its potency. The major finding of the current work is that the presence of appropriate number of hetero atoms (NH, OH) in a compound makes it more efficient than the number of labile groups (i.e., hydroxyl groups). Additionally, the position of hetero atoms in a compound and orientation also play a vital role in its efficacy. It was also screened for in vitro anti-inflammatory activity by membrane stability method, where it has shown 90.8% protection of RBC hemolysis. Thus, compound 3 with effective structural features may have good anti-inflammatory activity. Communicated by Ramaswamy H. Sarma

Pyrazole and Indazole Semihemiporphyrazine Complexes of Rhenium Tricarbonyl: A Structure/Properties Study

AbstractThe semihemiporphyrazines are a class of ligands comprised of a heterocycle ring and an isoindoline unit linked through a bridging nitrogen atom. These bidentate ligands can be altered in the exocyclic heteroatom position on the isoindoline and in the identity of the heterocycle. Herein, we present a series of Re(CO)3X (X=Cl, Br, py) complexes of indazole and pyrazole‐based semihemiporphyrazines. Changing the ligand and the axial position at the metal alters the character of the complexes, including the structure, tautomerization and charge of the chelate. Modifications to the semihemiporphyrazine also alter the electronic structure of the resultant Re(CO)3 complexed as demonstrated in their UV‐visible spectra. In addition to full characterization, we carried out density functional theory (DFT) and time‐dependent density functional theory (TDDFT) to interrogate the electronic structures of these compounds.

The Structural Design of Dual‐Element‐Doped Graphene for Iodine Reduction Reaction: Density Functional Theory Study

AbstractDual‐element‐doped graphene has been widely used in the counter electrode due to its enhanced catalytic activity. However, experiments lack a fundamental understanding of the doping effects accounting for the enhanced catalytic activity of dual‐element‐doped graphene. Here, we selected heteroatoms with different electronegativity (e. g., N: 3.0, P: 2.1, Se: 2.4, O: 3.5) based on the C atom with electronegativity of 2.5, then N atoms and heteroatoms co‐doped graphene (N/X‐G, X=P, Se, O) were constructed to investigate the effects of the electronegativity, the doping configuration and position of heteroatoms, the edge structure of graphene on iodine reduction reaction by density functional theory. After a detailed analysis of the electronic structure of N/X‐G, it revealed that the doping of dual‐element could lead to more electrons transfer to the area near heteroatoms, and thus providing more electrons for iodine species. The results of this study indicated that the effects of the dual‐element doping could be divided into three categories, and these principles provide theoretical guidance for further design of the dual‐element‐doped graphene.

Cooperative coupling strategy for constructing 0D/2D carbon nitride composites with strengthened chemical interaction for enhanced photocatalytic applications

• Tight electronic coupling was established between g-C 3 N 4 and CDs via a new strategy. • CSCl-C 3 N 4 features ultrathin nanosheets and broadened light harvesting. • The reasonable structure model and location of heteroatoms were calculated by DFT. • CSCl-C 3 N 4 is well suitable for photocatalytic degradation of TC and H 2 evolution. • The possible mechanism of photocatalytic reactions has been put forward. It is difficult for hydrophobic g-C 3 N 4 to construct tight heterogeneous connection with hydrophilic carbon dots (CDs), resulting in deficient charge transfer and restricted interfacial attachment between two components. Doping is an efficient strategy to firmly strengthen the hybridization of g-C 3 N 4 /CDs composites by inducing robust π–π conjugates or covalent chemical bonds for strong CDs anchoring to g-C 3 N 4 . In this work, a novel CDs anchored and S, Cl co-doped carbon nitride (CSCl-C 3 N 4 ) nanosheet is rationally designed and successfully fabricated for strong interfacial connection of g-C 3 N 4 /CDs. During the formation process, chlorine atoms are doped within the CDs and C-Cl covalent bond is detected. The strong interaction anchors CDs on g-C 3 N 4 and endows heterojunctions more compact connection. Systematic analyses demonstrate that CSCl-C 3 N 4 exhibits remarkably enhanced photocatalytic performance for water splitting. Loading 0.5 wt% CDs to S, Cl co-doped C 3 N 4 achieves the optimal photocatalytic activity among a series of samples (192.49 μmol∙h −1 ), as evidenced by 25 times that of pristine C 3 N 4 for generating hydrogen. Furthermore, the composite also exhibits considerable photocatalytic activity for photodegradation of tetracycline, in which the degradation rate is 15.3 times that of pristine C 3 N 4 . Density functional theory calculations and experimental results are employed to investigate the doping positions of heteroatoms within composites. ∙O 2 − was verified for predominating during photodegradation process to remove tetracycline by radical scavenge experiments. Based on the significant performance of CSCl-C 3 N 4 , the possible mechanism of photocatalytic reactions is put forward. The study provides a novel perspective for modifying nanostructures and constructing heterogeneous interfaces with compact connection via combining anchoring of CDs and doping strategies. The newly fabricated CSCl-C 3 N 4 is a considerable photocatalyst in multifunctional applications for solar energy conversion and pollution abatement.

Pluronic F127/carfilzomib-based nanomicelles as promising nanocarriers: synthesis, characterization, biological, and in silico evaluations

In this work, we designed a drug delivery nanosystem based on oil-in-water Pluronic F127 nanomicelles to encapsulate and control the release of the antineoplasic drug carfilzomib (CFZ), and hypothesized that CFZ entrapment might result in a better effective and more localized cytotoxic effect on cancerous cells and to reduce its undesirable side effects for in vitro and in vivo applications. Pluronic F127/CFZ nanomicelles showed a high drug encapsulation efficiency (74.8%) and were allowed to achieve a sustained release pattern. Computational analyses were conducted to increase understanding of the nature and strength of mutual interactions between Pluronic F127 and CFZ. Simulation data indicated that the position of heteroatoms on CFZ influences the strength of attractive interactions in the Pluronic F127/CFZ nanomicelles. Cytotoxic activity of free and encapsulated CFZ was assayed in several cancerous cell lines, SHY-SY5Y human neuroblastoma, MCF7 breast, and HeLa cervical cancer cells employing the MTT colorimetric assay. We found that Pluronic F127/CFZ nanomicelles exhibited greater anti-proliferative activity than free CFZ (lower IC50s) and induced evident morphological alterations in cancer cells. Caspase-3 activity was assessed to determine the main mechanism of drug-induced cell death. Compared to free CFZ, our formulation only increased caspase-3 activity in HeLa cells. To examine the short-term toxicity of F127/CFZ nanomicelles, intravenous injections of free CFZ and F127/CFZ nanomicelles at three doses of 0.25 mg/kg, 0.5 mg/kg, and 1 mg/kg for five consecutive days were administered to an animal model. The potential anti-bactericidal activity of this new formulation was also assayed against four standard bacteria, including Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis. Unfortunately, no significant bacteria-killing effects were detected despite other drugs of the same family showing promising results. Still, our new formulation showed desirable anti-cancer effects and might be a good therapeutic modality for cancer treatment.

Effect of the heteroatom presence in different positions of the model asphaltene structure on the self-aggregation: MD and DFT study

In this study, a series of heteroatoms including nitrogen, oxygen, and sulfur were added to different positions of the model asphaltene structure to study the effect of the heteroatom presence in the self-aggregation of the model asphaltenes. Molecular Dynamics was used to calculate Solubility Parameters, Radial Distribution Function, and Relative Solubility Parameters. Additionally, Reactivity Parameters, Electrostatic Potential, Reduced Density Gradient, and Independent Gradient Model were calculated using the Density Functional Theory to further investigate the Molecular Dynamics results. This study indicated that heteroatoms' diversity and their positions in the model asphaltene structure had an essential role in forming the model asphaltene aggregates. Four different sites in the model asphaltene structure were selected to study the impact of the heteroatom position in the self-aggregation. The presence of heteroatoms in the aliphatic side-chain proved to be more effective in increasing the self-aggregation process in comparison to the aromatic ring position. The heteroatoms' presence in the terminal position of the aliphatic side-chain increased the self-aggregation strength more than other sites in the aliphatic side-chain based on the terminal heteroatoms' ability to perform hydrogen bond formation. Additionally, heteroatoms in the middle of the aliphatic side-chain increased the CH…C dispersion interaction by the carbons' polarization. The heteroatoms in the aliphatic side-chain sites, especially in the terminal position, decreased the asphaltenes' solubility in the heptane and toluene more than the aromatic ring position.

Sulfur atom manipulates geometric isomerism of diphosphinine oxides for efficient delayed fluorescence diodes

Geometric isomerism has significant influences on intermolecular interactions. Therefore, despite the challenge, geometry manipulation is desired for developing high-performance optoelectronic materials. Herein, we demonstrate that heteroatom incorporation is a feasible approach to control cis- and trans- configurations of diphosphinine oxide compounds. Molecular geometries are highly dependent on heteroatom position, which is manifested by a cis- (cDPDPbDTO) and a trans- dithiophene-fused diphosphinine dioxide (tDPDPcDTO). It is showed that effects between S and P atoms bonded with the same C atoms bend the fused ring of cDPDPbDTO, giving rise to its cis-configuration. In contrast to trans-featured tDPDPcDTO containing a planar fused ring, cDPDPbDTO reveals more compact packing mode, accompanied by limited π-π stacking, and remarkably condensed excited states. Consequently, in addition to higher carrier mobility, cDPDPbDTO is much more effective in quenching suppression. Doped with a bluish green thermally activated delayed fluorescence (TADF) dye 2CzPN, cDPDPbDTO hosted film achieves fourfold increased radiative rate constant, and tenfold and sixfold decreased singlet and triplet nonradiative rate constants, respectively, as well as a 40%-improved reverse intersystem crossing (RISC) efficiency (97%). As the result, cDPDPbDTO endows its TADF systems with the state-of-the-art photoluminescence and electroluminescence quantum efficiencies of 95% and 26%, respectively.

Selenium-Substituted Non-Fullerene Acceptors: A Route to Superior Operational Stability for Organic Bulk Heterojunction Solar Cells.

Non-fullerene acceptors (NFAs) for organic solar cells (OSCs) have significantly developed over the past five years with continuous improvements in efficiency now over 18%. However, a key challenge still remains in order to fully realize their commercialization potential: the need to extend device lifetime and to control degradation mechanisms. Herein, we investigate the effect of two different molecular engineering routes on the widely utilized ITIC NFA, to tune its optoelectronic properties and interactions with the donor polymer in photoactive blends. Heavier selenium (Se) atoms substitute sulfur (S) atoms in the NFA core in either outer or inner positions, and methyl chains are attached to the end groups. By investigating the effects of these structural modifications on the long-term operational stability of bulk-heterojunction OSC devices, we identify outer selenation as a powerful strategy to significantly increase device lifetime compared to ITIC. Combining outer selenation and methylation results in an impressive 95% of the initial OSC efficiency being retained after 450 h under operating conditions, with an exceptionally long projected half-lifetime of 5600 h compared to 400 h for ITIC. We find that the heavier and larger Se atoms at outer-core positions rigidify the molecular structure to form highly crystalline films with low conformational energetic disorder. It further enhances charge delocalization over the molecule, promoting strong intermolecular interactions among acceptor molecules. Upon methylation, this strong intermolecular interaction stabilizes acceptor domains in blends to be resilient to light-induced morphological changes, thereby leading to superior device stability. Our results highlight the crucial role of NFA molecular structure for OSC operational stability and provide important NFA design rules via heteroatom position and end-group control.

Studies on the relationship between the structure of pyrimidinecarboxylic, pyridazinecarboxylic and pyrazinecarboxylic acids and their antimicrobial and cytotoxic activity

Diazinecarboxylic acids (pyridazine-3-carboxylic, pyridazine-4-carboxylic, pyrimidine-2-carboxylic, pyrimidine-4-carboxylic, pyrimidine-5-carboxylic and pyrazine-2-carboxylic acids) were characterized by means of spectroscopic (FT-Raman, FTIR, UV, 1HNMR, 13CNMR) and thermogravimetric analysis as well as antimicrobial and cytotoxic tests. The structures of diazinecarboxylic acids were calculated by the DFT method (B3LYP/6-311G(d, p). For the most stable conformers, the energy of HOMO and LUMO molecular orbitals, the geometric (HOMA, GEO, EN, I6) and magnetic (NICS) aromaticity indices, NBO electronic charge distribution, sEDA and pEDA indexes, Wiberg Bond Order, Wiberg Index and theoretical IR and NMR spectra have been calculated. The energies of protonating and deprotonating acids were also calculated. The effect of the nitrogen heteroatom position in the aromatic ring in relation to the position of the carboxyl group on the electronic charge distribution, thermal stability, antimicrobial and cytotoxicity activities of the examined acids was determined. Antimicrobial activity of tested acids against of Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosaand Candida albicanswas calculated based on MTT colorimetric assay (MCA). The cytotocic effect of diazynecarboxylic acids was examined in A375 melanoma cell line and DLD-1 cell line. A biplot analysis was performed in order to determine the correlations between selected parameters of the tested compounds and relative cell viability of E. coli, B. subtilis, P. aeruginosa, C. albicans, A375 and DLD-1 cell lines. Thermal behaviour of all investigated carboxylic acids was investigated using thermogravimetry (TG) and differential scanning calorimetry (DSC) techniques in flowing air atmosphere. All compounds are stable in room temperature.

An effective and versatile strategy for the synthesis of structurally diverse heteroarylsilanes via Ir(iii)-catalyzed C-H silylation.

A versatile silylation of heteroaryl C–H bonds is accomplished under the catalysis of a well-defined spirocyclic NHC Ir(iii) complex (SNIr), generating a variety of heteroarylsilanes. A significant advantage of this catalytic system is that multiple types of intermolecular C–H silylation can be achieved using one catalytic system at α, β, γ, or δ positions of heteroatoms with excellent regioselectivities. Mechanistic experiments and DFT calculations indicate that the polycyclic ligand of SNIr can form an isolable cyclometalated intermediate, which leaves a phenyl dentate free and provides a hemi-open space for activating substrates. In general, favorable silylations occur at γ or δ positions of chelating heteroatoms, forming 5- or 6-membered C–Ir–N cyclic intermediates. If such an activation mode is prohibited sterically, silylations would take place at the α or β positions. The mechanistic studies would be helpful for further explaining the reactivity of the SNIr system.

Unveiling the theoretical mechanism of purely organic room temperature phosphorescence emission and heteroatomic effects on singlet-triplet intersystem crossing for isopropylthioxanthone derivatives

In this work, the density functional theory (DFT) and time-dependent density functional theory (TDDFT) method were performed to investigate the mechanism of purely organic room temperature phosphorescence emission and heteroatomic effect on the electronic structures and photochemistry for the isopropylthioxanthone (ITX) and its derivatives. We designed a series of compounds by replacing sulfur atom on the heterocyclic ring and oxygen atom on the double bond of ITX by the atoms from the same group, which were named as O-, Se-HC-ITX, and S-, Se-DB-ITX. The result shows that both different heteroatoms and different positions of heteroatoms have a prominent impact on the photochemical properties of ITX derivatives. With the change of heteroatoms and their positions, the molecular structures are distorted causing the change of electron densities distribution and energy levels of the frontier molecular orbitals. The energy gaps between lowest unoccupied molecular orbitals (LUMOs) and the highest occupied molecular orbitals (HOMOs) are red-shifted from 6.83 to 5.28 eV with the heteroatom changed from O to Se, which is relative to the energy-level configuration. As a result, the maximum absorption wavelengths of the UV absorption spectra are red-shifted from 218 to 259 nm, and the fluorescence and phosphorescence emission spectra can be tuned from the ultraviolet region to the visible region even to the infrared region with the heteroatom on the double bond changed from O to Se. Moreover, the change of heteroatoms also introduces into the heavy-atom effect which enhances the spin-orbital coupling (SOC) between singlet and triplet excited states dramatically and increases the probability of singlet-triplet intersystem crossing (ISC) happening which lead to purely organic room temperature phosphorescence (RTP). Hence, this work demonstrates that the change-heteroatom strategy can make the tunable photochemical properties realizable, which provides a new strategy for researches to design molecular systems.

A General Rhodium Catalyst for the Deuteration of Boranes and Hydrides of the Group 14 Elements.

Pinacolborane, catecholborane, triethylsilane, triphenylsilane, dimethylphenylsilane, 1,1,1,3,5,5,5-heptamethyltrisiloxane, triethylgermane, triphenylgermane, and triphenylstannane deuterated at the heteroatom position have been catalytically prepared in 50-70% isolated yield, through H/D exchange between the D2 molecule and the respective boranes and hydrides of the group 14 elements, in the presence of the rhodium(I)-monohydride catalyst precursor RhH{κ3-P,O,P-[xant(PiPr2)2]} (xant(PiPr2)2 = 9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene).

Controlling Two-Photon Action Cross Section by Changing a Single Heteroatom Position in Fluorescent Dyes.

The optimization of nonlinear optical properties for “real-life” applications remains a key challenge for both experimental and theoretical approaches. In particular, for two-photon processes, maximizing the two-photon action cross section (TPACS), the figure of merit for two-photon bioimaging spectroscopy, requires simultaneously controlling all its components. In the present Letter, a series of difluoroborates presenting various heterocyclic rings as an electron acceptor have been synthesized and their absorption, fluorescence, photoisomerization, and two-photon absorption features have been analyzed using both experimental and theoretical approaches. Our results demonstrate that the TPACS values can be fine-tuned by changing the position of a single heteroatom, which alters the fluorescence quantum yields without changing the intrinsic two-photon absorption cross section. This approach offers a new strategy for optimizing TPACS.

Far Away from Flatland. Synthesis and Molecular Structure of Dihetera[3.3.n]propellanes and Trihetera[3.3.n]propellanes: Advanced Analogues of Morpholine/Piperazine.

An approach to di- and trihetera[3.3.n]propellanes (n = 2-4 ), advanced morpholine and piperazine analogues, is developed. The key step of the reaction sequence included a [3 + 2] cycloaddition reaction of unsaturated vicinal dicarboxylic acid derivatives and in situ generated azomethine ylide resulting in the formation of the pyrrolidine ring. One more heteroaliphatic ring (i.e., pyrrolidine or tetrahydrofuran) was annelated by nucleophilic cyclization of the appropriate 1,4-dielectrophilic intermediates. There were 11 examples of the title products obtained in 3-5 steps on a multigram scale with 10-72% overall yields. Additionally, molecular structures of homologous dihetera[3.3.n]propellanes, analogues of morpholine, were obtained from X-ray diffraction studies and analyzed using exit vector plots (EVPs). It was shown that the scaffolds obtained are somewhat larger as compared to the parent morpholine and bicyclic 3-oxa-7-azabicyclo[3.3.0]octane. Moreover, despite very similar chemical structures, they provide a very distinct spatial position of heteroatoms, which is clearly seen from the conformation adopted by a formal eight-membered ring including both N and O atoms (i.e., crown, boat-chair, twist chair-chair, and boat-boat for the oxaza[3.3.2]-, -[3.3.3]-, -[4.3.3]propellanes, and 3-oxa-7-azabicyclo[3.3.0]octane, respectively).

Impact of heteroatom (S and N) position and change in central ring of anthracene with heterocyclic ring on charge transport and optical properties in anthratetrathiazole (ATTz)

ABSTRACTBased on the results of quantum mechanical calculation extracted with the B3LYP functional at the density functional theory level, the impact of replacement of thiophene with thiazole rings in anthratetrathiophene (ATT) molecule was evaluated. Furthermore, to study the effect of substitution in the central benzene ring of anthracene, cyclic rings with heteroatoms were introduced. The optical and charge transport characteristics were also examined when the position of sulphur and nitrogen at the periphery of anthracene were interchanged. To analyze the electronic transitions in these molecules, TD-DFT calculations were performed. The outcome of the calculations suggest that swapping of the central benzene with hetero-cyclic rings and the change in positions of the sulphur and nitrogen have considerable influence on various properties, i.e. energies of HOMO & LUMO, HOMO-LUMO energy gap, ionization potential (IP), electron affinity (EA), hole extraction potential (HEP), electron extraction potential (EEP) and reorganization energies (λ). Moreover, all the studied molecules posed better hole and electron transport characteristics than standard materials. The smaller values of hole and electron reorganization energies suggest that this analysis offers a supportive background for prospective design and fabrication of high-performance charge-transport materials.HighlightsOn interchanging position of S and N at the periphery of ATTz results, a small change in absorption maxima.Replacement of central six-member ring of anthracene with a five-member ring in ATTz molecule results in blue-shifted absorption.Molecules where sulphur facing outward at the periphery of ATTz are better for hole transporting materials.On changing the position of S-atom (inward to outward position) at the periphery of ATTz lead to destabilization of both HOMO and LUMO levels.

Quantum interference independence of the heteroatom position

We introduce a novel calculation to the transmission coefficient of molecules with single impurity. The study employs tight binding Green’s function method and new derived analytical formula to investigate chromene-like (even) and doped azulene-like (odd) model systems. Under certain circumstances, these specific even and odd models are respectively shown single and double critical points, at which the transmission becomes independent of the heteroatom position. Moreover, a counterintuitive correlation between the transmission and the coupling strength has analytically and numerically been approved: the transmission decreases with strengthening lead-nodes couplings.