Dihedral Angle Research Articles

A visual and sensitive sensor for colorimetric and fluorescent recognition of Fe3+/2+, theoretical calculation and strip applications in wine

Total iron ions (Fe3+/2+) are a critical factor influencing wine quality and stability. A novel “turn-on” fluorescent probe (E)-2-((4-(5-methyl-1H-benzo[d]imidazol-2-yl)benzylidene)amino)phenol (probe MBBP) for monitoring Fe3+/2+ in wine was developed. It was designed with benzimidazole as the fluorophore and o-aminophenol as the Fe3+/2+ recognition site, simple and easy to prepare. The probe itself in EtOH/H2O (v: v, 49:1) emitted weak fluorescence and produced strong blue fluorescence after adding Fe3+/2+. The sensing of Fe3+/2+ was performed via the nucleophilic attack of Fe3+/2+ to imine groups of the probe with a 1:1 binding stoichiometry, and the fluorescence enhancement of the sensor was mainly due to the generation of compound 3 with the ICT effect. Results demonstrated that the probe exhibited high selectivity and sensitivity with a lower detection limit of 0.054 nM than previously reported Fe3+/2+ probes. In addition, based on the TD-DFT method and CAM-B3LYP and PBE0 functional theory, the significant changes in the dihedral angle stemmed from the isomerisation and rotation of the C = N bond. Probe MBBP was successfully applied to detect Fe2+/3+ in wine by intelligent software and the rapid detection of Fe3+/2+ using strips was also conducted.

Tunable circularly polarized luminescence behaviors caused by the structural symmetry of achiral pyrene-based emitters in chiral co-assembled systems

The regulation of circularly polarized luminescence (CPL) behavior is of great significance for practical applications. Herein, we deliberately designed three achiral pyrene derivatives (Py-1, Py-2, and Py-3) with different butoxy-phenyl substituents and the chiral binaphthyl-based inducer (R/S-B) with anchored dihedral angle to construct chiral co-assemblies, and explored their induced CPL behaviors. Interestingly, the resulting co-assemblies demonstrate tunable CPL emission behaviors caused by the structural symmetry effect of achiral pyrene-based emitters during the chiral co-assembly process. And in spin-coated films, the dissymmetry factor (gem) values were 9.1 × 10-3 for (R/S-B)1-(Py-1)10, 5.6 × 10-2 for (R/S-B)1-(Py-2)7, and 8.6 × 10-4 for (R/S-B)1-(Py-3)1, respectively. The strongest CPL emission (|gem| = 5.6 × 10-2, λem = 423 nm, QY = 34.8 %) was detected on (R/S-B)1-(Py-2)7 due to the formation of regular and ordered helical nanofibers through the strong π-π stacking interaction between the R/S-B and the achiral Py-2 emitter. The strategy presented here provides a creative approach for progressively regulating CPL emission behaviors in the chiral co-assembly process.

Analysis and optimization of the coupling effect for duct-rotor based on aerodynamic performance

The duct has the potential to provide additional thrust, which can enhance the overall aerodynamic performance of the system. Nonetheless, since the duct and the rotor interact with each other, it is crucial to consider their interaction while optimizing the system for improved performance. This paper presents a parameterization approach for the duct and rotor. Primarily, a rotor space characterization and parameter modeling method that utilizes Bezier curves, class functions/shape functions, and Bernstein polynomials is proposed. Next, the aerodynamic performance of different key factors of the duct-rotor system is calculated and analyzed using a numerical calculation method. The study found that the coupling effect of camber yf and chord length parameter Bc3 had a significant impact on the thrust coefficient, with a contribution rate of 7.3 %. Correspondingly, the coupling effect of camber yf and torsion angle parameter Ba3 had a great influence on the Figure of Merit (FM), with a contribution rate of 7.1 %. The thrust coefficient and FM of the rotor-duct system were optimized by taking the coupling effect into consideration, and the optimized ducted rotor was verified by experimental measurement. The test results shows that the high thrust case achieves a 25.60 % increase in thrust coefficient, while the high-FM case establishes an 8.89 % increase in the FM. This implies that the collaborative optimization based on the coupling effect of duct and rotor shape parameters can effectively improve the system's performance, such as thrust coefficient and Figure of Merit.

Characterization of torsion plate energy-absorbing members and multi-objective optimization of mechanical properties

In order to prevent damage to the support equipment caused by rock burst, a torsion plate energy absorption member is designed to be used with hydraulic columns. Explicit dynamic simulation is used and compared with the tests. The equations of structural parameters to the mean value of the reaction force (Fmean), specific energy absorption (SEA), and mean squared deviation (σ) are constructed based on the response surface method. The structural parameters are optimized using MOPSO. The results indicate that the torsion plate exhibits excellent energy absorption characteristics. The error rate of the simulation compared to the test is less than 5%, indicating a high level of simulation accuracy. All three sets of response fitted equations have R2 above 0.97, indicating a good fit. The three evaluation indexes demonstrate a trend of increasing then decreasing as the torsion angle increases. The wall thickness is positively correlated with the influence of each parameter index, while the effect of fillet radius is reversed. The maximum relative error of the predicted value is 9.50%. After optimization, the Fmean is effectively increased by more than 78%, the SEA is increased by more than 24.72%. The σ is increased by 8.31%, the optimization effect is remarkable.

Square-planar nickel/copper(II) complexes of (E)-2-(((2-ethylphenyl)imino)(phenyl)methyl)phenol: Supramolecular analysis, keto-enol tautomerism, polymorphism and antibacterial activities

A new Schiff base proligand, (E)-2-(((2-ethylphenyl)imino)(phenyl)methyl)phenol (HL), was synthesized from 2-hydroxybenzophenone and 2-ethylaniline and its coordination chemistry with nickel(II) and copper(II) acetate explored. In solution, the proligand HL undergoes ketoimine-enolimine tautomerism which settles exclusively into an enolimine form in the solid-state. Interestingly, while a single crystalline habit was obtained for the nickel complex 1 (block-shaped single crystals), the copper species 2 was found to solidify in two detectable polymorphs: block-shaped crystals (2a, monoclinic space group P21/c) and rhombic crystals (2b, triclinic space group P-1). Single-crystal X-ray diffraction studies reveal that the N,O Schiff base ligand chelates the divalent metal ions with square-planar geometry in the isostructural 1 and 2a and in a distorted square-planar geometry with a dihedral chelate-plane angle of 27.9° in 2b. The copper complex 2 exhibits significant antibacterial activity against the E. coli and medium activity against S. aureus bacteria. The physical properties of the complexes were further probed using thermal techniques, while their electronic structure was investigated by electrochemistry and electronic absorption spectroscopy.

Unveiling interatomic distances influencing the reaction coordinates in alanine dipeptide isomerization: An explainable deep learning approach.

The present work shows that the free energy landscape associated with alanine dipeptide isomerization can be effectively represented by specific interatomic distances without explicit reference to dihedral angles. Conventionally, two stable states of alanine dipeptide in vacuum, i.e., C7eq (β-sheet structure) and C7ax (left handed α-helix structure), have been primarily characterized using the main chain dihedral angles, φ (C-N-Cα-C) and ψ (N-Cα-C-N). However, our recent deep learning combined with the "Explainable AI" (XAI) framework has shown that the transition state can be adequately captured by a free energy landscape using φ and θ (O-C-N-Cα) [Kikutsuji et al., J. Chem. Phys. 156, 154108 (2022)]. In the perspective of extending these insights to other collective variables, a more detailed characterization of the transition state is required. In this work, we employ interatomic distances and bond angles as input variables for deep learning rather than the conventional and more elaborate dihedral angles. Our approach utilizes deep learning to investigate whether changes in the main chain dihedral angle can be expressed in terms of interatomic distances and bond angles. Furthermore, by incorporating XAI into our predictive analysis, we quantified the importance of each input variable and succeeded in clarifying the specific interatomic distance that affects the transition state. The results indicate that constructing a free energy landscape based on the identified interatomic distance can clearly distinguish between the two stable states and provide a comprehensive explanation for the energy barrier crossing.

Semiconducting Polymers Based on Asymmetric Thiadiazoloquinoxaline for Augmented In Vivo NIR-II Photoacoustic Imaging.

A photoacoustic (PA) imaging technique using the second near-infrared (NIR-II) window has attracted more and more attention because of its merits of deeper penetration depth and higher signal-to-noise (S/N) ratio than that using the first near-infrared (NIR-I) one. However, the design and development of high-performance PA imaging contrast agents in the NIR-II window is still a challenge. A semiconducting polymer, constructed by asymmetric units, exhibits regiorandom characteristics that effectively increase the distortion of the backbone. This increase in the degree of twist can regulate the twisted intramolecular charge transfer (TICT) effect, resulting in an enhancement of the PA signal. In this paper, an asymmetric structural acceptor strategy is developed to improve the PA signals of the resulting semiconducting polymer (PATQ-MP) in the NIR-II window with improved brightness, higher S/N ratio, and better photothermal conversion efficiency compared to polymers with the same main-chain structure containing a symmetric acceptor. DFT analysis showed that PATQ-MP containing an asymmetric acceptor monomer had a larger dihedral angle, which effectively improved the PA signal intensity by enhancing the TICT effect. The PEG-encapsulated PATQ-MP nanoparticles exhibit promising performance in the PA imaging of mouse tumors in vivo, demonstrating the clear identification of microvessels as small as 100 μm along with rapid metabolism within a span of 5 h. Therefore, this work provides a unique molecular design strategy for improving the signal intensity of PA imaging in the NIR-II window.

An investigation on the torsional vibration of a FG strain gradient nanotube

AbstractIn this work, an attention is paid to the prediction of torsional vibration frequencies of functionally graded porous nanotubes based on the Lam strain gradient elasticity theory. The nanotubes are formed of functionally graded porous nanomaterials that vary in the radial direction. This study also aims to obtain the analytical solution of the strain gradient model presented by Lam for torsional vibration response, in a simple manner, for different rigid or restrained boundary conditions. The torsion angle of a functionally graded nanotube is defined by an infinite Fourier series. Then, the Stokes’ transformation is applied to force the boundary conditions to the desired state. An eigenvalue problem is established with the help of the two systems of equations obtained. This eigenvalue problem, which includes deformable springs at both ends of the nanotube, appears as a general analytical solution that can find torsional vibration frequencies. It is shown that the vibrational responses can be significantly influenced by the through‐radius gradings of material, material length scale parameters and deformable springs of the functionally graded nanotubes and consequently can be predicted by giving proper values to torsional spring parameters.

Sulfide Melt Wetting Properties in Earth's Mantle: New Constraints From Combined 2D and 3D Imaging

AbstractBase‐metal sulfur liquids (mattes) play a crucial role as metasomatic agents and carriers of highly siderophile elements (HSE) within the Earth's mantle. Prior research has predominantly focused on sulfur‐poor metallic liquids involved in core formation scenarios. We conducted high‐pressure experiments using a multi‐anvil apparatus to investigate the effects of pressure, non‐ferrous compounds in mattes, and the mineral composition of the silicate host on matte wetting properties. Specifically, we explored conditions representing both the lithospheric (6 and 7 GPa) and sub‐lithospheric Earth's mantle (13 GPa). We characterized the experiments using the distribution of the dihedral angle in backscattered‐electron sections and the sphericity and network topology of the mattes in tomography scans. Our findings reveal distinct behaviors: while the matte in olivine‐dominated samples exhibited behaviors consistent with previous studies, such as high dihedral angle values (94° and 100°), the majorite‐bearing sample run at 13 GPa formed a disseminated network with a mean dihedral angle of 43°, below the connectivity threshold of 60°. Furthermore, in an experiment involving a garnet‐bearing silicate host, we observed a decrease in the matte's dihedral angle to 72°. Our results suggest that pressure within mafic hosts contributes to increased matte mobility in the sub‐lithospheric Earth's mantle, especially inasmuch as the stability of garnet phases is concerned. Consequently, mattes within subducted oceanic crusts may efficiently transport HSE into surrounding lithologies, while mattes within depleted, more harzburgitic lithologies and the ambient mantle may remain trapped within the silicate host at low melt fractions.

FINITE SHEAR STRAIN BASED ON IMAGE ANALYSIS FOR RECTANGULAR SECTION SHAFT WITH LARGE ASPECT RATIO

This paper describes the shearing strain distribution obtained by using image analysis proposed in this study when large torsion is applied to a rectangular cross-section shaft. As is well known, the shearing strain distribution for rectangular cross-section shaft have already been investigated by Saint-Venant. However, since this theory is based on the assumption that torsional angle is relatively small, it is not necessarily rational under large torsion. Therefore, in our previous study, using the image analysis based on the Natural Strain theory, where the commutative law of strain is applicable and the rigid body rotation can be removed accurately from shearing strain component, the shearing strain distributions have been investigated for the rubber shaft having square cross section. In the present paper, these distributions are investigated for a rectangular cross section with a large aspect ratio rather than a square shape. In particular, these distributions on the long side in rectangular cross-section are compared with those on the short sides. Consequently, the difference between the distribution of shearing strain obtained by the image analysis in this study and measurements based on Saint-Venant's theory increases as torsional deformation increases and this tendency is observed particularly on the short side.

Insights on molecular modeling and supramolecular arrangement of bilastine polymorphs.

The advancement in the development of second-generation drugs in the field of antihistamines represents a significant milestone in the management of allergic diseases, targeting the effects of histamine. The efficacy of bilastine in treating allergic disorders has sparked interest in investigating its polymorphism, a crucial property that impacts quality, safety, and effectiveness as per regulatory guidelines. This study examines the polymorphism of bilastine, focusing on two crystalline forms labeled as Form I and Form II. Utilizing advanced analytical techniques, the research explores the structural characteristics and molecular interactions within these forms. Geometric parameters, such as bond lengths, bond angles, and torsion angles, are examined to comprehend molecular conformations and crystal packing arrangements. Hydrogen bonding, covalent bonds, and van der Waals forces contribute to the unique supramolecular arrangements in these forms.This study provides a significant contribution to understanding bilastine's polymorphism, offering critical insights to researchers and regulatory bodies to ensure the quality, efficacy, and safety of antihistamine products. The molecular conformation of two bilastine forms was obtained through DFT with the exchange-correlation functional M06-2X and the 6-311 + + G(d,p) basis set, and the results were compared with the experimental X-ray. The atomic coordinates were obtained directly from the crystalline structures, and charge transfer was also investigated using frontier molecular orbitals (HOMO and LUMO), and MEP map in order to evaluate the energies associated with charge transfers and regions of high electron affinity. The geometric and topological parameters and intermolecular interactions in the crystals were analyzed using Hirshfeld Surface.

Impact of crystal and molecular structure of three novel thiosulfonate crystals on their vibrational and NMR parameters

Due to antimicrobial potential of S-containing compounds, the current study explores experimentally the crystal and molecular structure of three new thiosulfonates at 100 K, notably S-ethyl 4-aminobenzene-1-sulfonothioate (1), S-ethyl 4-acetamidobenzene-1-sulfonothioate (2), and S-methyl 4-acetamidobenzene-1-sulfonothioate (3). Theoretical analysis between their molecular structure and vibrational IR, Raman, as well as NMR parameters is given. The details of -SO2-S- structural motif are analyzed theoretically using HOOH, HS-SH and H3CS-SCH3, as model molecules. The experimental structural parameters, as determined by low temperature X-ray diffraction method are accurately predicted using DFT-B3LYP combined with large and flexible aug-cc-pVTZ basis set. In case of C-S-S-C dihedral angle the crystal forces are responsible for larger difference with respect to isolated molecules, predicted in the gas phase. In addition, electronic properties of the title compounds are explored using theoretical calculations of their geometric and magnetic aromaticity indexes and substituent push-pull effect. The obtained results provide a deeper insight into their molecular structure and IR/Raman and NMR spectroscopic properties. Finally, these compounds could be directly used in future in vitro investigation of therapeutic potential of the studied and structurally similar compounds.

Effects of fuselage shape on helicopter aerodynamic performance in case of intermeshing-rotor interference

To study the influence of fuselage shape on the aerodynamic performance of a helicopter under the interference of an intermeshing-rotor, a numerical simulation method of flow field under the forward flight state of Synchropter is established based on the lattice Boltzmann method. Firstly, the Maryland helicopter was calculated to verify the scientific validity of the method. Then, the simplified S-97 fuselage was used as the object of analysis to analyze the aerodynamic data such as surface pressure, friction, and lift resistance of the fuselage with different head curvature, cross-section shapes, and transition segments under Synchropter interference with different attack angles in forward flight. The results show that increasing the radius of curvature of the nose can reduce the total drag of the fuselage; the fuselage with a circular cross-section shape has better aerodynamic characteristics of lift resistance, and the fuselage with rhombic cross-section shape has better transverse stability; the transition section with backward position, smaller upward dihedral angle, and smooth transition can avoid serious airflow separation and achieve the purpose of drag reduction.

Ferrocene-based chemosensor creates molecular logic circuit for selective detection of Hg2+ and Cu2+

A cation sensor, R, with multi-channel signaling was developed by creating a covalent connection between a ferrocene unit and pyridyl-pyrazole rings. Spectroscopic techniques and single-crystal X-ray diffraction were employed to characterize sensor R. The examination revealed a dihedral angle of 140.09° for the pyridyl-pyrazole rings. The receptor R functions as a highly selective multi-channel chemosensor, exhibiting chromogenic, fluorogenic, and electrochemical capabilities. In a CH3CN/water (9:1) solvent mixture, receptor R operates as a multi-channel signaling chemosensor, selectively detecting Hg2+ and Cu2+ ions in water. The original pale-yellow solution turned orange upon Hg2+ addition and green upon Cu2+ addition. A new low energy (LE) band at 460 nm was detected after adding one equivalent of Hg2+. In cyclic voltammetry (CV), the half-wave potential (E1/2) of 462 mV shifted to 622 mV, whereas in differential pulse voltammogram (DPV), the oxidation peak underwent an anodic shift (ΔE1/2 = 155 mV). The maximum emission at 423 nm was lowered by more than 90 % when the concentration of Hg2+ ions reached one equivalent. One equivalent addition of Cu2+ results in a new LE band at 740 nm. Cu2+ ions suppress the oxidation peak current in both the CV and DPV of R. It also demonstrates chelation-enhanced fluorescence effect (CHEF) with Cu2+. The interaction between cations and R was elucidated through 13C NMR titration. DFT calculations revealed the binding mode. Its distinctive fluorescence demonstrates a 'turn-on' response to Cu2+ and a 'turn-off' response to Hg2+ with selectivity. This concept has been applied to create a molecular combinatorial logic circuit.

Impact of helical elongation of symmetric oxa[n]helicenes on their structural, photophysical, and chiroptical characteristics.

The adjustment of the main helical scaffold in helicenes is a fundamental strategy for modulating their optical features, thereby enhancing their potential for diverse applications. This work explores the influence of helical elongation (n = 5-9) on the structural, photophysical, and chiroptical features of symmetric oxa[n]helicenes. Crystal structure analyses revealed structural variations with helical extension, impacting torsion angles, helical pitch, and packing arrangements. Through theoretical investigations using density functional theory (DFT) calculations, the impact of helical extension on aromaticity, planarity distortion, and heightened chiral stability were discussed. Photophysical features were studied through spectrophotometric analysis, with insights gained through time-dependent DFT (TD-DFT) calculations. Following optical resolution via chiral high-performance liquid chromatography (HPLC), the chiroptical properties of both enantiomers of oxa[7]helicene and oxa[9]helicene were investigated. A slight variation in the main helical scaffold of oxa[n]helicenes from [7] to [9] induced an approximately three-fold increase in dissymmetry factors with the biggest values of|glum| of oxa[9]helicene (2.2 × 10-3) compared to|glum|of oxa[7]helicene (0.8 × 10-3), findings discussed and supported by TD-DFT calculations.

Supramolecular Chirality Achieved by Assembly of Small π-Molecules of Octahydrobinaphtols with Axial Chirality.

5,5',6,6',7,7',8,8'-Octahydro-1,1'-bi-2-naphthol (hbNaph) is an axially chiral molecule consisting of a smaller π-electronic system than that for 1,1'-bi-2-naphthol (BINOL). The absorption and circular dichroism (CD) bands of hbNaph appear in a shorter wavelength region below 310 nm, compared to those of BINOL, and its fluorescence is in the invisible UV region. However, increasing the concentration of hbNaph in solution up to 0.1 M results in its absorption edge gradually extending to longer wavelength, with a shoulder around 330 nm, and finally increasing to about 450 nm. At the same time, blue fluorescence is clearly observed, as well as a new CD band with the sign of the Cotton signals reversed from those obtained for dilute solutions. These results suggest that, at high concentrations, hbNaph forms chiral aggregates, in which π-electrons are delocalized over multiple molecules. To further understand how molecular axial chirality is transformed to supramolecular chirality, we attempted to construct aggregate models by simulating CD spectra using a time-dependent density functional theory. The only reasonable model obtained was that involving the counterclockwise R-enantiomer forming a clockwise helix, while the clockwise S-enantiomer forms a counterclockwise helix. We conclude, however, that, for such helixes, the most plausible model is densely packed and forms when the dihedral angle between the two phenol rings of hbNaph is acute, at around 75°, which reproduces the aggregate-induced CD sign inversion.

Axial compressive behavior of T-shaped welded multi-partition composite members

T-shaped welded multi-partition composite members, which are made of several rectangular concrete-filled steel tubes, are proposed to speed up the fabrication procedure. Seven half-scale T-shaped specimens were tested by considering the section height-to-width ratio and slenderness ratio. In the test, a slight torsion angle was measured when the instability failure along the asymmetric axis occurred, indicating the specimens had good torsion resistance. When the relative slenderness ratio of the specimen was larger than 0.44, the specimens failed due to the instability along the asymmetric axis. Parametric numerical analysis is conducted by considering the slenderness ratio, cross-section dimension, steel ratio, and material strength. The results show that the strength of concrete negatively impacts the ductility of the specimens, leading to a decrease of 43%, while the strength of the material positively influences the stability of the specimens. The formulas from different traditional codes are verified by the parametric numerical analysis results, indicating most codes can conservatively predict the sectional bearing capacity, but overestimate the stability coefficient of the specimens by neglecting the reduction effect of the excessive height-to-depth ratio. Recommendations are provided for calculating the stability coefficient under axial compression applicable to T-shaped welded multi-partition composite members.

Torsional Deformity Significantly Impacts Lateral Ankle Radiographic Imaging Parameters.

Background Optimal lateral ankle imaging is important for the diagnosis and treatment of multiple ankle conditions. The effects of limb deformity on lateral ankle imaging are not well described and are clarified in this osteological study. Materials and methods We utilized an osteological collection and imaged all specimens after the first positioning of the talus in the lateral position and positioning the tibia and fibula to match. We then measured the relative positions of the tibia and fibula and their widths to calculate standard ratios. All measurements were evaluated for reliability using intra-class correlation coefficients. Multiple regression analysis determined how patient characteristics, tibial torsion, and medial proximal tibial angle affected various lateral ankle imaging ratios. Results The intra-class correlation coefficient was excellent for all measurements. In the multiple regression analysis, all five imaging ratios had at least one statistically significant outcome. The anterior tibiofibular interval (ATFI)-tibial width (TW) ratio (ATFI:TW) had only one association with sex and had the lowest standard deviation. All other parameters had variation with tibial torsion and/or medial proximal tibia angle (MPTA). The mean ATFI was 1.06 ± 0.21 cm and 1.19 ± 0.23 cm for females and males, respectively. Conclusions Patient sex and tibial torsion impacted the fidelity of lateral imaging parameters. ATFI:TW may pose the greatest utility given its minimal association with deformity parameters and low standard deviation.

Modulating thermal and electrical conductivities in polymers: An approach toward extracting molecular design rules through atomistic simulations

Polymers are extensively employed in diverse industries, including electrical equipment and electronic devices. Recent technological advancements have intensified the demand for dielectric polymers with both high insulation resistance and high thermal conductivity. We employed molecular dynamics simulations to clarify the intricate relationship between molecular structures, thermal conductivity, and ionic mobility from an atomistic point of view. Examined polymers include polyethylene, polyvinyl alcohol, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polychlorotrifluoroethylene, polyoxymethylene, and polyethylene oxide. Based on the elucidated correlations among force field parameters, we found that the parameters can be clustered into four groups: group 1 (atomic and bond parameters and force constant of the bond angle), group 2 (equilibrium angle and force constant of dihedral angle), and group 3 (side chain atom charges). Thermal conductivity showed relationships with parameters in group 1, with correlation coefficients mostly exceeding 0.7 in the absolute value. Considering the correlations between the parameters, we systematically altered the parameters within each group and computed thermal conductivity and ionic mobility. When altering the force field parameters of groups 1 and group 2, a trade-off relationship between thermal conductivity and ionic mobility becomes evident. Conversely, altering the force field parameters in group 3 increased thermal conductivity while decreasing ionic mobility, breaking the trade-off relationship. The proposed clustered-parameter variation method can predict the changes in the electrical and thermal conductivity of polymers through molecular structure modifications. The method, being a general and first-principles approach, is likely to have significant advantages in the molecular design across a diverse range of polymers.

Benzo[a][1,4]benzothia-zino[3,2-c]phenothia-zine.

The title compound, C22H12N2S2, crystallizes in space group P21/c with four mol-ecules in the asymmetric unit. The heterocyclic mol-ecule is quasi-planar with a dihedral angle between the phenyl rings on the periphery of the mol-ecule of 1.73 (19)°. Short H⋯S (2.92 Å) and C-H⋯π [2.836 (3) Å] contacts are observed in the crystal with shorted π-π stacking distances of 3.438 (3) Å along the b axis. Surprisingly, and unlike a closely related material, this mol-ecule readily forms large crystals by sublimation and by slow evaporation from di-chloro-methane. The maximum absorbance in the UV-Vis spectrum is at 533 nm. Emission was measured upon excitation at 533 nm with a fluorescence λmax of 658 nm and cutoff of 900 nm.