eV For Compounds Research Articles

1D Lead Bromide Hybrids Directed by Complex Cations: Syntheses, Structures, Optical and Photocatalytic Properties.

This study presents the synthesis, structural characterization, and evaluation of the photocatalytic performance of two novel one-dimensional (1D) lead(II) bromide hybrids, [Co(2,2'-bpy)3][Pb2Br6CH3OH] (1) and [Fe(2,2'-bpy)3][Pb2Br6] (2), synthesized via solvothermal reactions. These compounds incorporate transition metal complex cations as structural directors, contributing to the unique photophysical and photocatalytic properties of the resulting materials. Single-crystal X-ray diffraction analysis reveals that both compounds crystallize in monoclinic space groups with distinct 1D lead bromide chain configurations influenced by the nature of the complex cations. Optical property assessments show band gaps of 3.04 eV and 2.02 eV for compounds 1 and 2, respectively, indicating their potential for visible light absorption. Photocurrent measurements indicate a significantly higher electron-hole separation efficiency in compound 2, correlated with its narrower band gap. Additionally, photocatalytic evaluations demonstrate that while both compounds degrade organic dyes effectively, compound 2 also exhibits notable hydrogen evolution activity under visible light, a property not observed in 1. These findings highlight the role of metal complex cations in tuning the electronic and structural properties of lead(II) bromide hybrids, enhancing their applicability in photocatalytic and optoelectronic devices.

New hydrazide-hydrazone derivatives containing coumarin and indole moiety: Synthesis, spectroscopic characterization and DFT studies

Two new compounds (3 and 4), coumarin indole derivatives with a hydrazide-hydrazone skeleton, were synthesized, and their spesctroscopic properties, including UV-vis, FTIR, and 1H-13C NMR were investigated experimentally and theoretically. The experimental data and DFT (density functional theory) results of the compounds matched well and showed good agreement. Moreover, the DFT/B3LYP/6-311G++(2d,p) calculations were utilized to perform HOMO and LUMO energy, net atomic charges, MEP surface, and NBO analysis for the optimized geometries of 3 and 4. NBO analysis revealed that the synthesized compounds exhibit high molecular stability because of significant hyperconjugative interactions. The experimental and theoretical band gaps (ΔEg) investigated in some organic solvents with different polarities were determined to be in the range of 2.68-2.75 eV and 3.22-3.25 eV for compound 3, and 2.69-2.77 eV and 3.41-3.47 eV for compound 4, respectively. The compounds demonstrated thermal stabilities with a Td value higher than 300 °C.

Di- and Tricyanovinyl-Substituted Triphenylamines: Structural and Computational Studies.

We report herein on the solid-state structures of three closely related triphenylamine derivatives endowed with tricyanovinyl (TCV) and dicyanovinyl (DCV) groups. The molecules described contain structural features commonly found in the design of functional organic materials, especially donor-acceptor molecular and polymeric architectures. The common feature noticeable in these structures is the impact of these exceptionally strong electron-accepting groups in forcing partial planarity of the portion of the molecule carrying these groups and directing the molecular packing in the solid state, resulting in the formation of π-stacks of dimers within the unit cell of each. Stacks are formed between phenyl groups bearing electron-accepting groups on two adjacent molecules. Short π-π stack distances ranging from 3.283 to 3.671 Å were observed. Such motif patterns are thought to be conducive for better charge transport in organic semiconductors and enhanced device performance. Intramolecular charge transfer is evident from the shortening of the observed experimental bond lengths in all three compounds. The nitrogen atoms (of the cyano groups) have been shown to be extensively involved in short contacts in all three structures, primarily through C-H···NC interactions with distances as short as 2.462 Å. The compounds reported here are (3,3-dicyano-2-(4-(diphenylamino)phenyl)-1λ3-allylidene)amide or tricyanovinyltriphenylamine, Ph3NTCV (1); 2-(4-(diphenylamino)benzylidene)-malononitrile or dicyanovinyltriphenylamine, Ph3NDCV (2); and (3,3-dicyano-2-(4-(di-p-tolylamino)phenyl)-1λ3-allylidene)amide or dimethyltricyanovinyltriphenylamine, Me2Ph3NTCV (3). Results of density functional theory calculations using DFT-B3LYP/6-31G(d,p) indicate the lowering of LUMO levels as a result of the introduction of these groups with band gaps of 3.13, 2.61, and 2.55 eV for compounds 1-3, respectively, compared with 4.65 eV calculated for triphenylamine. This is supported by the electronic and fluorescence spectra of these molecules with absorption λmax of 483, 515, and 545 nm for compounds 1, 2, and 3, respectively.

Synthesis and characterization of new hybrid decatungstate anions (CTAB)4W10O32 : toward heterogeneous photocatalysis

ABSTRACT In the present study, hybrid decatungstate based photocatalysts, [(C16H33)N(CH3)3]4[W10O32], were synthesized through the reaction of hexadecyltrimethylammonium surfactant (CTAB) and sodium decatungstate Na4W10O32.2.6 H2O (W10) using different molar ratios of W10:CTAB (1:1 for compound 1 and 1:3 for compound 2) under aqueous conditions. The characterization of these hybrid materials was carried out using FT-IR spectroscopy, UV-visible spectroscopy, TGA, XRD and SEM, which confirmed the formation of [(C16H33)N(CH3)3]4[W10O32] materials. The influences of the molar ratio on the bandgap energy, photocatalytic activity and material morphology were compared and discussed in detail. FT-IR Spectroscopy indicates that CTAB reacted with W10, producing an insoluble product in aqueous media as expected. UV-Visible spectroscopy revealed that the hybrid material with a low amount of CTAB absorbed in the visible area compared to the other one, with the optical bandgap decreasing to 2.42 eV for compound 1 in particular. The UV-visible photocatalytic degradation of carbamazepine (CBZ) in aqueous solution demonstrated the efficiency of both compounds with approximately 46 and 88% of CBZ transformation after 7 hours of exposure for compound 1 and 2, respectively. These results prove that the new hybrid decatungstate has effective photocatalytic activity, which depends on the synthesis conditions.

Facile synthesis and photodetection characteristics of new pyrrolo[2,3-b]pyrrole-based metal-free organic dyes containing phenols as the potential candidates towards energy conversion

A new characteristic with inexpensive preparation tools and best application performance is needed. These new properties have been achieved by using novel heterocyclic dyes by attaching different electron-rich aromatics to the pyrrolo[2,3-b]pyrrole system. A new derivatives of diethyl 3,4-diamino-1,6-diphenyl-1,6-dihydropyrrolo [2,3-b]pyrrole-2,5-dicarboxylate (PPy) (compound 1) was easily and efficiently synthesized using catalyzed condensation reaction. The final push-pull conjugated dyes were yielded by azo coupling with resorcinol, and 2-naphthol, denoted as compounds 2 and 3, respectively. Very good adhesive and homogenous thin films of these compounds are successfully prepared by thermal evaporation technique. On the basis of its corrected analytical and spectral data, the structure of these compounds was determined. The relation between dye structures, photophysical, and molecular structures had been discussed. The unique simulation characteristics of the prepared compounds 1–3 were achieved by density functional theory, DFT/B3LYP, using 6–311 ++ G (d,p) basis set. Optical spectra have revealed a large direct band gap at 3.99, 3.15, and 2.85 eV for compounds 1, 2, and 3 respectively, corresponding to π−π* transitions. Finally, an experimental approach was used to determine the exciton binding energy to depict Frenkel exciton binding energy. The properties of these compounds proved that it is more suitable as a potential application for energy conversion.

Synthesis and characterization of new multinary selenides Sn4In5Sb9Se25 and Sn6.13Pb1.87In5.00Sb10.12Bi2.88Se35

Multinary selenides, Sn4In5Sb9Se25 (1) and Sn6.13Pb1.87In5.00Sb10.12Bi2.88Se35 (2) were synthesized by solid-state sintering reactions. These compounds were initially observed resulting from the exploratory synthesis of multinary selenides in In–Sn–Sb–Se systems. Sn4In5Sb9Se25 crystallizes in a monoclinic lattice with a ​= ​31.820(2) Å, b ​= ​4.0241(3) Å, c ​= ​19.703(2) Å, β ​= ​114.246(5)°, and V ​= ​2300.4(3) Å3; space group C2/m (No. 12); Z ​= ​2. Sn6.13Pb1.87In5.00Sb10.12Bi2.88Se35 crystallizes in a monoclinic lattice with a ​= ​31.6883(5) Å, b ​= ​4.0709(1) Å, c ​= ​26.5406(4) Å, β ​= ​105.710(1)°, and V ​= ​3295.8(2) Å3; C2/m (No. 12); Z ​= ​2. The structures of both compounds are constructed with two building units of NaCl100-type [M2x−42+M43+Se2x+2]∞1 and NaCl111-type [M2y−23+Se3y−3]∞2. The structural anisotropy leads to a columnar or layered shape and strongly preferred orientation along [010] direction upon two compounds. These materials exhibit black color comprising a semiconducting property. Band gaps observed in electrical conductivity measurements are 0.66 ​eV and 0.62 ​eV for compound 1 and 2, respectively. UV–vis–NIR spectroscopy and the electronic band structure calculations at the density functional theory (DFT) level indicate the results of the semiconducting behaviors. Measurements of Seebeck coefficient indicates p-type semiconductors for both compounds.

Unusual Atmospheric Water Trapping and Water Induced Reversible Restacking of 2D Gallium Sulfide Layers in NaGaS2 Formed by Supertetrahedral Building Unit

Two new ternary materials NaGaS2 (1) and the Fe-doped phase of NaGaS2, NaFe0.135Ga0.865S2 (2), have been synthesized by employing polysulfide flux. Single crystal XRD analyses of 1 and 2 show that the structure is built up of adamantane-like Ga4S10 super tetrahedral fundamental building units. These admantane-like units are connected through their corners to form [GaS2]∞– layers that are stacked one over the other with Na ions residing in between the layers to balance the charge. Both the materials have the remarkable ability to absorb atmospheric water molecules and moisture from undried solvents as verified by TG analysis and FT-IR and XPS studies. The process of water absorption leads to stable distinct material NaGaS2·∼H2O (1·H2O) and NaFe0.135Ga0.865S2·∼H2O (2·H2O) with restacked layers different from original crystal structure. This structural transformation is reversible as the transformed structures 1·H2O and 2·H2O can be returned to their original structures 1 and 2, respectively, upon heating. DFT calculation study reveals that a spontaneous exergonic hydration reaction takes place as outlined in NaGaS2 + H2O → NaGaS2·H2O with the energy release, ΔE of −73.9 kJ mol–1. DFT calculation predicts an increase in the unit cell parameters of b and c directions and shrinkage along the a direction of hydrated phase 1·H2O with an overall volume increase of 36.6%. Structural transformation affects their physical properties as the pristine compound 1 possess Na+ ion conductivity of 2.88 × 10–7 S cm–1 at 22 °C, whereas the hydrated compound 1·H2O displays ∼40 times increased ion conductivity of 1.25 × 10–5 S cm–1 at the same temperature. DRS studies show very similar optical band gaps of ∼4 eV for compounds 1 and 1·H2O, respectively, in reasonable agreement with the DFT­(HSE) band gap estimation but more than 1 eV above the DFT­(PBE)-predicted band gaps of ∼2.4 eV. A sorption study indicates selective adsorption of water over MeOH, EtOH, and CH3CN with a maximum water uptake of 2.6 H2O per formula unit at P/P0 = 0.9. A Karl Fischer titration study shows that NaGaS2 (1) is certainly capable of adsorbing water from wet methanol and can be useful as a fast desiccating agent.

MII2M3IIIF3(Te6F2O16) (MII = Pb, Ba; MIII = Al, Ga): New mixed anionic tellurites with isolated Te6 coplanar rings

Three new isostructural mixed anionic tellurites, namely, Pb2Al3F3(Te6F2O16) (1), Pb2Ga3F3(Te6F2O16) (2) and Ba2Ga3F3(Te6F2O16) (3), have been synthesized successfully by hydrothermal reactions. Their structures feature a novel 3D framework composed of 1D GaO4F2/AlO4F2 octahedral chains joined together with isolated (Te6F2O16)10− anionic rings. The charge-balance cations of Pb2+ or Ba2+ are located at the six-member polyhedral ring tunnels of the structures. The 0D (Te6F2O16)10− coplanar anionic ring is first reported in fluorotellurites, formed by two TeO4 and four TeO3F groups via corner-sharing. Thermogravimetric analyses revealed that their thermostabilities are in the following order: Pb2Al3F3(Te6F2O16) (1), Ba2Ga3F3(Te6F2O16) (3) and Pb2Ga3F3(Te6F2O16) (2). Optical diffuse reflectance spectra showed that these solids are wide band gap semiconductors with Eg of 4.1, 4.2 and 4.4 ​eV for compounds 1–3 respectively. The band gaps of compounds 1 and 2 are determined by O, Te and Pb atoms while the band gap of compound 3 is determined by O and Te atoms based on the theoretical calculations.

Optical and dielectric relaxation of transition metal-based organic-inorganic hybrid materials

The [(CH3)3NH]CdCl3 (1) and [N(CH3)3H]CoCl3·2H2O (2) compounds were obtained by slow evaporation at room temperature and characterized by X-ray powder diffraction patterns. These compounds were crystallized in the orthorhombic system, in Pbnm and Pnma space groups, respectively. The optical properties were measured by means UV–Vis absorption spectrometry in order to deduce the absorption coefficient α and optical band gap Eg. The Tauc model was used to determine the optical gap energy of the synthesized compounds 1 and 2. Data analysis revealed the existence of two optical transition mechanisms. The calculated values of the direct and indirect band gaps (Egd, Egi) for both samples were estimated between 5.41 and 5.30 eV for compound 1; and between 4.02 and 3.82 eV for compound 2. The dependence of the optical constants, the refractive index (n) and the extinction coefficient (k) of compounds 1 and 2 were calculated and the results discussed. The normal dispersion of refractive index of the samples was described using the Wemple–DiDomenico single oscillator method. The optical dispersion parameters Eo and Ed were determined according to the above oscillator method. We employed dielectric spectroscopy to investigate the dipolar dynamics in the both compound. The evolution of the dielectric loss as a function of frequency showed a distribution of relaxation times; which is probably due to the reorientational dynamics of alkyl chains in compound 1, analyzed with the Cole–Cole formalism. Various relaxation processes and their locations of compound 2 were analyzed according to the fitted data of the Havriliak–Negami (HN) function. Different relaxation processes were found to belong to non-debye relaxation. The dielectric constants were composed of two dielectric relaxation peaks, DC conduction and electrode polarization (EP) effect. The determined values of relaxation time are characteristic of the co-operative reorientation of the trimethylammonium cation.

Syntheses and characterizations of polymeric silver iodoplumbates, and iodoplumbates with lanthanide complexes

Novel heterometallic Ag–iodoplumbates [Ln(DMSO)8]Pb2Ag2I9 [Ln = La(1), Gd(2), Tm(3)] were prepared by reactions of LnCl3, PbI2, AgNO3 and KI in dimethyl sulfoxide (DMSO). The same reactions without reactant AgNO3 produced new iodoplumbates [Ln(DMSO)8][(DMSO)Pb4I11] [Ln = La(4), Pr(5), Nd(6)]. All Ln3+ ions are solvated with eight DMSO molecules in the reactions, forming [Ln(DMSO)8]3+ complex cations to act as counterions to the iodometallate anions. In compounds 1–3, two AgI4 tetrahedra and two PbI6 octahedra are connected into the 1D heterometallic Ag–Pb iodometallate [Ag2Pb2I9]n3n−via face-sharing. The [Ag2Pb2I9]n3n− anionic chains run parallel along the b axis in 1, and along the a axis in 2 and 3. The [Ln(DMSO)8]3+ cations are located between the chains. In compounds 4–6, two PbI6 and two PbI5O octahedra are interlinked end to end via sharing common faces to generate a 1D [(DMSO)Pb4I11]n3n− chain, which represents a new member of iodoplumbate aggregates. In the [(DMSO)Pb4I11]n3n− chain, the Pb2+ ions are joined not only via μ-I bridges, but also via μ-O bridges. The μ-O oxygen bridging has never been observed in iodoplumbates. Solid state optical absorption spectral analyses show optical band gaps in the range of 2.25–2.88 eV for compounds 1–6. Blue shift of the absorption edge caused by copolymerization of the AgI4 unit occurs on the iodoplumbates.

Energy structure of thin films of carbazole derivatives with metal electrodes

Study of charge carrier transport in organic electroluminescent devices, organic photovoltaic devices, and organic field-effect transistors is one of the most important points. In order to realize comparable electron and hole transport in thin organic films with electrodes the energy structure of such devices are of great importance. In this work, we have studied electrical properties and energy structure of two carbazole derivatives. The threshold energy of photoconductivity quantum efficiency is 2.90 eV and optical energy gap is 3.3 eV in thin films is obtained. The values of work function of ITO, Au, Cu and Pd electrodes are energetically close to conductivity level of holes and holes injection dominates from electrodes. In these thin films local trapping states of holes are situated at holes conducting level. When electrode is Al layer the local shallow trapping states for electrons at Et = 0.10 eV for compound 1 and at Et = 0.18 eV for compound 2 are determined.

A TDDFT and PCM-TDDFT studies on absorption spectra of N-substituted 1,8-naphthalimides dyes

The electronic absorption spectra of 39 N-substituted 1,8-naphthalimides dyes have been investigated in the framework of time-dependent density functional theory (TDDFT) and polariable continuum TDDFT (PCM-TDDFT). The B3LYP and PBE0 hybrid functionals together with 6-31+G(d) basis set were selected to calculate the excitation energies of 3–30 lowest-lying singlet excited states. Comparing the experimental spectra with calculated excitation energy, the mean absolute error (MAE) of TD-B3LYP/6-31+G(d) is 0.21 eV. Including solvent effect, the PCM-TD-B3LYP/6-31+G(d) provides a very high accuracy for compounds 1–5 (in cyclohexane) and 20–26 (in chloroform), but a larger error with 0.37–0.47 eV for compounds 6–19 and 27–39 (in DMF). The PBE0 hybrid functional provides a slight higher accuracy than B3LYP. The MAE is 0.28 eV for PCM-TD-B3LYP/6-31+G(d), and 0.21 eV for PCM-TD-PBE0/6-31+G(d), respectively. All calculation reveals that the maximum absorption band mainly results from the π → π ∗ transition from HOMO to LUMO.

Magneto-optical properties of new manganese oxide compounds

The investigation of magneto-optical properties of manganese magnetic oxide compounds containing (MnO 6) 9- and (MnO 6) 8- octahedral magnetoactive complexes — perovskites, orthomanganites, pyrochlores and ilmenites — and influence of Bi 3+ and Pb 2+ ions on their magneto-optical activity (MOA) was carried out in the energy range of 1.5–4.5 eV. MOA of investigated compounds was shown to be defined by the transitions in (MnO 6) 9- and (MnO 6) 8- complexes, the frequencies of these transitions were determined. The strong increase of MOA at the energies 4–4.5 eV in compounds containing both Bi 3+ (or Pb 2+) and Mn 4+ ions was observed. The enhancement of charge-transfer transitions contribution to MOA due to the admixture of Bi 3+(Pb 2+) ions' (6p)-wave functions to the molecular orbitals of (MnO 6) 8- complexes is considered to be the most likely mechanism of this phenomenon.

Transport and dielectric properties of lisicon

The ionic and electronic conductivities of Lisicon with compositions Li 14Zn(GeO 4) 4-(A) and Li 12Zn 2(GeO 4) 4-(B) have been determined in the temperature range 306–578 K. It has thus been shown that the ionic transport number is nearly unity throughout the temperature range. The activation energies for lithium motion were found to be 0.6 eV and 0.47 eV for compounds A and B. These values are very close to the values of the heat of transport q ∗ Li + 0.59 eV and 0.50 eV respectively, obtained from thermoelectric power (θ t) measurements. The total ionic conductivity of the pellets of Lisicon was found to decrease with increasing average grain size in the range 20–78 μ. Electrode effects on the ionic conductivity are also reported for silver and TiS 2 electrodes. The electron/hole conductivity was studied using the Wagner cell technique. The activation energies for electron and hole transport for A were estimated as 1.02 eV and 1.39 eV and for B as 0.89 eV and 1.49 eV, respectively. The variation of the dielectric parameters ϵ', ϵ” and tan δ have been studied for sample A between 10 Hz-100 kHz. The high frequency dielectric constant (at 100 kHz) was 21.4. The ϵ' versus ϵ” (Cole-Cole plot) is also presented.