Energy Gap Research Articles

Spin-Orbit Coupling and Admixture Coefficients in SA-CASSCF and MS-CASPT2, and Triplet Excitation Yield Simulated via Trajectory Surface Hopping and Calibrated SA-CASSCF in 1,2-Dioxetane Derivatives.

The energy gaps, spin-orbit coupling (SOC), and admixture coefficients over a series of the configurations are evaluated by the SA-CASSCF/6-31G, SA-CASSCF/6-31G*, SA-CASSCF/ANO-RCC-VDZP, and MS-CASPT2/ANO-RCC-VDZP to reveal the extent of the inaccuracy of the SA-CASSCF. By comparing the mean absolute errors for the energy gaps and the admixture coefficient magnitudes (ACMs) measured between the SA-CASSCF/6-31G, SA-CASSCF/6-31G*, or SA-CASSCF/ANO-RCC-VDZP and the MS-CASPT2/ANO-RCC-VDZP, the SA-CASSCF/6-31G is selected as the electronic structure method in the nonadiabatic molecular dynamics simulation. The major components of the ACMs of the SA-CASSCF/6-31G and MS-CASPT2/ANO-RCC-VDZP are identified and compared; we find that the ACMs are underestimated by the SA-CASSCF/6-31G, which is verified by the reasonable triplet quantum yield simulated by the trajectory surface hopping and the calibrated SA-CASSCF/6-31G. The magnitude of the singlet-triplet mixing positively correlates to the hopping probability between the mixed singlet and triplet states, which is confirmed by the computed S-T transition probability.

Size Effect on Ultrafast Dynamics of the Photoexcited 7Be Electron in 7Be@C2n (2n = 60, 70, and 80).

The ultrafast excited-state dynamics of endohedral fullerenes are crucial in their photophysical and photochemical processes when they are employed as photovoltaic devices, photocatalytic devices, and single-molecule devices. In this study, by employing the ab initio non-adiabatic molecular dynamics simulations based on the time-dependent Kohn-Sham (TD-KS) method, we theoretically studied the size effect on ultrafast excited-state decay dynamics of the photoexcited 7Be electron in endohedral fullerenes 7Be@C2n (2n = 60, 70, and 80). These excited-state decay dynamics, which involve the charge-transfer process, occur in an ultrafast time scale of about 3 ps. The larger fullerene cage delays the excited-state decay process because the presence of significant energy gaps and phonon modes in large endohedral fullerenes slows the non-radiative electron transitions among energy levels. Those findings not only provide physical insights into the excited-state decay dynamics of confined atoms but also stimulate further research to develop efficient endohedral-fullerene-based photoelectric and photocatalytic devices.

Meso-β, β-β' trifused porphyrins: synthesis, spectral, electrochemical and DFT studies and their femtosecond third-order nonlinear optical properties.

Meso-β, β-β' trifused porphyrins incorporating two distinct active methylene groups (MN = malononitrile and IND = 1,3-indanedione) and their corresponding metal complexes with Cu(II) and Zn(II) have been synthesized with good to excellent yields and characterized by various spectroscopic techniques and spectrometric methods. Single crystal X-ray analysis of the Zn(II) complex ZnTFPMB(MN)2 (where TFP = trifused porphyrin and MB = mono benzo) revealed a ruffled nonplanar 'armchair' type conformation with a twist angle of 24.10°. The absorption spectra showed a significant bathochromic shift in both the B- and Q-bands, extending into the near-infrared (NIR) region, particularly for π-extended trifused porphyrins. The cyclic voltammograms of MN-appended trifused porphyrins revealed unusual redox behavior, likely due to chemical reactions occurring at the electrode surface during electroreduction. The HOMO-LUMO energy gap for the π-extended porphyrins (MTFPMB(VCN)2) was effectively reduced to ≤1.5 V, compared to ∼2.23 V for the parent porphyrins. Additionally, the femtosecond third-order nonlinear optical properties of the synthesized trifused porphyrins and reported Ni(II) complexes were investigated using the Z-scan technique. Most of the studied porphyrins exhibited promising three-photon absorption coefficients and cross-section values, suggesting their potential applications in optical limiting, bio-imaging, and advanced optoelectronics.

The Best of Both Worlds: ΔDFT Describes Multiresonance TADF Emitters with Wave-Function Accuracy at Density-Functional Cost.

With their narrow-band emission, high quantum yield, and good chemical stability, multiresonance thermally activated delayed fluorescence (MR-TADF) emitters are promising materials for OLED technology. However, accurately modeling key properties, such as the singlet-triplet (ST) energy gap and fluorescence energy, remains challenging. While time-dependent density functional theory (TD-DFT), the workhorse of computational materials science, suffers from fundamental issues, wave function-based coupled-cluster (CC) approaches, like approximate CC of second-order (CC2), are accurate but suffer from high computational cost and unfavorable scaling with system size. This work demonstrates that a state-specific ΔDFT approach based on unrestricted Kohn-Sham (ΔUKS) combines the best of both worlds: on a diverse benchmark set of 35 MR-TADF emitters, ΔUKS performs as good as or better than CC2, recovering experimental ST gaps with a mean absolute deviation (MAD) of 0.03 eV at a small fraction of the computational cost of CC2. When combined with a tuned range-separated LC-ωPBE functional, the excellent performance extends to fluorescence energies and ST gaps of MR- and donor-acceptor TADF emitters and even molecules with an inverted ST gap (INVEST), rendering this approach a jack of all trades for organic electronics.

Boosting Multicolor Emission Enhancement in Two-Dimensional Covalent-Organic Frameworks via the Pressure-Tuned π-π Stacking Mode.

Covalent-organic frameworks (COFs) are dynamic covalent porous organic materials constructed from emissive molecular organic building blocks. However, most two-dimensional (2D) COFs are nonemissive or weakly emissive in the solid state owing to the intramolecular rotation and vibration together with strong π-π interactions. Herein, we report a pressure strategy to achieve the bright multicolor emission from yellow to red in the 2D triazine triphenyl imine COF (TTI-COF). Intriguingly, the TTI-COF experiences a 24-fold enhancement under a mild pressure of 2.7 GPa compared with the initial state. Joint experimental and theoretical results reveal that the restricted intramolecular chemical bond vibrations and the reduced π-π interactions originating from the offset stacking mode account for the significant pressure-induced emission enhancement. Furthermore, such piezochromic behavior may be ascribed to the decreased energy gap and enhanced intermolecular interaction. Our investigation offers constructive guidelines for designing 2D COF materials with high photoluminescence performance.

Mechanical Modulation of S0-S1 and S0-T1 Energy Gaps of 11-cis and All-trans Retinal Schiff Bases.

The retinal Schiff base is a chromophore of significant biological relevance, as it is responsible for capturing sunlight in rhodopsins, which are photoactive proteins found in various living organisms. Additionally, this chromophore is subjected to various mechanical forces in different proteins, which alter its structure and, consequently, its properties. To thoroughly understand the mechanical response limits of the retinal excitation energy, a simple first-order formalism has been developed to quantify the chromophore's optimal mechanical response to applied external forces (on the order of tens of pN). Additionally, the response to larger forces is analyzed by using an algorithm to explore the potential energy surfaces. It can be concluded that the retinal Schiff base exhibits a significant mechanical response and that the optimal forces and displacements involve certain coordinates typically of low frequency, showing differences between the S1 and T1 states, as well as between the 11-cis and all-trans isomers. Additionally, the possibility of mechanically modulating the bond length alternation using mechanical forces is ruled out.

The spin-wave energy spectrum and transition temperature of the two-dimensional VSe2-like: a retarded Green’s function method study

Based on the recent discovery of intrinsic magnetism in monolayer films VSe2, we have constructed a two-dimensional (2D) Heisenberg model incorporating the 1Tand 2Hstructures. These configurations consist of three layers: the upper and lower surface layers and a middle layer. Using the retarded Green's function method, we investigate the spin-wave energy spectrum, spin-wave density of states, and transition temperature of the system. It is found that in the 2Hstructure, the spin-wave energy spectrum of the system exhibits three direct energy gaps, with one branch being independent of the wave vector. Further analysis shows that at this constant energy, a particular surface state emerges in the 2Hstructure. In contrast, the spin-wave energy spectrum in the 1Tstructure features only two energy gaps-one direct energy gap1 and one indirect energy gap3-without forming a unique surface state. Single-ion anisotropy and interlayer interactions between the upper and lower surface layers influence the energy gaps in the spin-wave energy spectrum and the system's transition temperature. This theoretical work sheds light on forming particular surface states in monolayer 2Hstructure magnetic materials. It provides crucial theoretical support for designing and fabricating next-generation low-dimensional magnetic random-access memory.

Selective Recognition of Oncogene Promoter C-Myc G-Quadruplex: Design, Synthesis, and In Vitro Evaluation of Naphthalimide and Imidazo[1,2-a]pyrazines for Their Anticancer Activity.

c-Myc is a transcription factor that is overexpressed in most human cancers. Despite its challenging nature, we have developed a series of naphthalimide-imidazopyrazine conjugates to target c-Myc. The library of synthesized derivatives was tested for their anticancer activity against a nine-panel of cancer cell lines. Compound 8eb showed excellent cytotoxicity against all the tested cancer cell lines, with the range of growth inhibition from -98.79% to 96.62% at a single-dose concentration of 10-5 M. Further, 8eb was employed for a 5-dose assay against the same cancer cell lines, which showed efficacy at varying concentrations with an MG-MID GI50 value of 2.61 μM. Biophysical studies were performed to explore the interaction of 8eb with c-Myc Pu27 over ct-DNA, oncogene promotor Pu22, and human telomere, with a binding constant value of 1.3 × 107 M-1. Additionally, experiments were performed to get insights into the interaction mechanism between 8eb and the c-Myc oncogene promoter. A molecular docking study unveiled the stacking of the compound with G4 DNA through groove binding, where very few reports are available, with a favorable binding energy of -9.2 kcal/mol. Moreover, the pharmacokinetic study and HOMO-LUMO energy gap analysis underscored the potency of the active candidate. The compound's binding ability toward HSA was also assessed, where results suggested effective binding of the compound to HSA, revealing its potential for easy delivery to the target site. The above findings suggested that these newly synthesized candidates with potent anticancer activity offer a promising avenue as G4 DNA c-Myc stabilizers.

Impact of Ligand Structure on Biological Activity and Photophysical Properties of NHC-Protected Au13 Nanoclusters.

N-heterocyclic carbene (NHC)-protected gold nanoclusters display high stability and high photoluminescence, making them well-suited for fluorescence imaging and photodynamic therapeutic applications. We report herein the synthesis of two bisNHC-protected Au13 nanoclusters with π-extended aromatic systems. Depending on the position of the π-extended aromatic system, changes to the structure of the ligand shell in the cluster are observed, with the ability to correlate increases in rigidity with increases in fluorescence quantum yield. Density functional theory analysis reveals that both synthesized Au13 nanoclusters are 8-electron superatoms but have distinct differences in the characteristics of the lowest unoccupied single-electron states. Qualitatively, this implies different mechanisms for excitations and their decay over the fundamental energy gap. Stability and photophysical studies were carried out to provide the emission lifetime and optical purity of the two clusters. Active intracellular uptake of the nanoclusters was confirmed in vitro using confocal microscopy in human epithelial carcinoma cells. Reactive oxygen species production was measured at 7% efficiency. The high cluster stability, photoluminescence quantum yields, and efficient cellular uptake in cancer cells suggest potential for these nanoclusters as highly efficient and tunable nanomedical platforms.

Magnetic and reusable Fe3O4/PPE-2 functional material for efficient photodegradation of organic dye.

Composite photocatalysts based on metal nanoparticles and functional polymers attract much attention compared to inorganic photocatalysts. In this study, a reusable magnetite/anion exchanger (Fe3O4/PPE-2) functional material is synthesized by a hydrothermal method, and its photocatalytic activity is evaluated for the photocatalytic degradation of Rhodamine B (RhB). The results from materials characterization confirm a well-defined morphology of magnetic Fe3O4/PPE-2 functional material and the formation of Fe3O4 nanocrystals with different shapes and sizes on the surface of anion exchange material (PPE-2). The optimized Fe3O4/PPE-2 in 180°C (FM180) photocatalyst exhibited a band gap energy of 1.90eV, demonstrating significant photocatalytic potential. Using RhB as a model pollutant, magnetic Fe3O4/PPE-2 (FM180) functional material achieved 98.2% degradation efficiency after 160min of visible light irradiation (rate constant k=0.03496 min-1). Efficiency of the photocatalytic materials, of photocatalytic degradation of RhB is 28.4% for pure anion exchanger (PPE-2), 56.5%, 64.7% and 98.2% for magnetic functional Fe3O4/PPE-2 materials, synthesized under conditions of 140°C (FM140), 160°C (FM160) and 180°C (FM180), respectively. Compared to individual PPE-2 anion exchange material and Fe3O4, the magnetic functional FM180 material exhibits a remarkable photocatalytic reaction rate as high as four times that of PPE-2, with superior reusability over 10 cycles. The computational study and Mott-Schottky plots verify the formation of the internal electric field. Possible reaction pathways for the photocatalytic degradation of RhB are presented. In addition, the results demonstrate that the Fe3O4/PPE-2 functional material very efficiently removed Rhodamine B from textile wastewater. This work offers a simple route for the preparation of magnetic and reusable Fe3O4/PPE-2 magnetic functional material that can be used in the water purification process.

New insights into structural, optical, electrical and thermoelectric behavior of Na0.5Bi0.5TiO3 single crystals

The single crystals of lead-free Na0.5Bi0.5TiO3 were grown using the Czochralski method. The energy gaps determined from X-ray photoelectron spectroscopy (XPS) and optical measurements were approximately 2.92 eV. The current-voltage characteristics, depolarization current, dc (σdc) and ac (σac) electrical conductivity, and Seebeck coefficient of the crystals were investigated. The frequency/temperature-dependent electrical properties were also measured and analyzed through complex impedance spectroscopy. An overlapping reversible insulator-metal transition (resistive switching) on nanoscales, caused by the electric field, was detected. Most of these properties were measured for the first time. The activation energy values determined from the conductivity data, the imaginary part of the electric impedance and the modulus indicate that the relaxation process in the high-temperature range is attributable to both single and double ionized oxygen vacancies, in combination with the hopping of electrons between Ti4+ and Ti3+. P-type electrical conductivity was also found. These discoveries create new possibilities of reducing the electrical conductivity of NBT and improving the process of effectively poling this material. Our results indicate the possibility of tuning the material properties by intentionally creating non-stoichiometry/structural defects (oxygen vacancies, cation excess and cation deficiency).

Value addition to wastes: photo/sono-catalytic and antimicrobial performance of nickel ferrite derived using iron tailing and Raney nickel catalyst processing wastes.

This research highlights a sustainable approach for the design and synthesis of a magnetic nickel ferrite (NiFe2O4) catalyst reutilizing industrial waste, specifically iron ore tailing and Raney nickel catalyst processing waste, by simple co-precipitation method. Transforming waste materials into high-performance catalysts, this study aligns with the principles of a circular economy, addressing both environmental waste and pollution. Structural characterization by X-ray diffraction (XRD) and microscopic (FESEM and TEM) revealed the formation of well crystalline nano ferrite with NiFe2O4 nanoparticles with cubic spinel structure. The ferromagnetic behavior with saturation magnetization of 43emu/g and low band gap energy (1.81eV) of the prepared catalyst supported its magnetic separation and activity under visible light. EDX and XPS analysis confirmed the purity of the sample with the existence of desired elements/ions. The prepared catalyst demonstrated significant photocatalytic and sonocatalytic activity under visible light and ultrasonic waves, respectively. The catalyst efficiently degraded the Reactive Red 35 (RR35), a model dye contaminant, in its aqueous solution (20-40mg/L) within 2h of the reaction. Besides its pollutant for dye removal, the catalyst also exhibits remarkable antibacterial activity, achieving a fivefold faster E. coli disinfection rate in comparison to traditional catalysts. Overall, the results established a lab-scale method for the synthesis of ferrite nanopowder from solid industrial wastes and provided inputs for developing a combined photo-sonocatalytic process for the degradation of different persistent organic contaminants including dyes.

Breakdown of the Kasha-Vavilov's rule in low-symmetry porphyrazines: Ultrafast intersystem crossing via high vibronic state.

Recently (Photochem Photobiol. 2023;100:1277-1289. doi:10.1111/php.13898), we described the anti-Kasha effect in tribenzo-6H-1,4-diazepinoporphyrazins with C2v symmetry, where the ultrafast spin changes successfully compete with the internal conversion. In this study, we show the presence of this effect in 2 (3),9 (10),16(17),23(24)-tetra-tert-butyl-29H,31H-phthalocyanine (1) and 1,4-di-[2-(2-methoxyethoxy)ethoxy]-29H,31H-phthalocyanine (2), which also possess reduced molecular symmetry and do not bear 6H-1,4-diazepine fragments. The anti-Kasha effect in 1 and 2 supplemented by Mg(II) tribenzo-6H-1,4-diazepinoporphyrazinates 3 and 4 exhibits a close-to-linear dependence on energy gap value between the zero vibrational levels of two lowest singlet excited states S1 0 and S2 0 (these states are degenerate in D4h symmetry) and enhances with increase. The theoretical kinetic model of excited state dynamics, which takes into account the observed effects and follows Fermi's golden rule, predicts the presence of an additional excited state with enhanced spin-orbit coupling compared to S1 0, S2 0 and the corresponding triplet states, which is not predicted by TDDFT calculations in the Born-Oppenheimer approximation. The combination of the above indicates that the key role in the observed anti-Kasha effect and the mechanism of dissipation of the excited state in porphyrazines and their analogs is played by vibronic excited states, which requires theoretical research methods beyond the Born-Oppenheimer approximation.

Structural, Electronic, and Magnetic Properties of Neutral Borometallic Molecular Wheel Clusters.

Atomic clusters exhibit properties that fall between those found for individual atoms and bulk solids. Small boron clusters exhibit planar and quasiplanar structures, which are novel materials envisioned to serve as a platform for designing nanodevices and materials with unique physical and chemical properties. Through past research advancements, experimentalists demonstrated the successful incorporation of transition metals within planar boron rings. In our study, we used first-principles calculations to examine the structure and properties of neutral boron clusters doped with transition metals, denoted as TMBn and TMB2n, where TM = Ti, Cr, Mn, Fe, Co, Nb, or Mo and n=8-10. Our calculations show that the TMB2n structures, which involve sandwiching metal atoms between two rings (called the drum configuration), and clusters with the single ring configuration, TMBn, are stable. These clusters typically have relatively large HOMO-LUMO energy gaps, suggesting high kinetic stability and low chemical reactivity. Moreover, the clusters display interesting magnetic properties, determined not only by the metal atoms but also by the induced magnetism of the boron rings. These structures have potential applications in spintronics and sensing. This work also provides a basis for studying magnetism in the one-dimensional limit.

Natural Compounds from Alhagi maurorum as Potential HCC and HepG2 Inhibitors: An Integrated Study using Pharmacophore Development, Molecular Docking, MD Simulation, and DFT Approaches.

The rise in the frequency of liver cancer all over the world makes it a prominent area of research in the discovery of new drugs or repurposing of existing drugs. This article describes the pharmacophore-based structure-activity relationship (3DQSAR) on the secondary metabolites of Alhagi maurorum to inhibit human liver cancer cell lines Hepatocellular carcinoma (HCC) and hepatoma G2 (HepG2) which represents the molecular level understanding for isolated phytochemicals of Alhagi maurorum. The definite features, such as hydrophobic regions, average shape, and active compounds' electrostatic patterns, were mapped to screen phytochemicals. The 3D-QSAR model generates pharmacophore-based descriptors and alignment of active compounds. Further, docking studies were performed on the active compounds to check out their binding affinity with the active site of the target proteins. It was further validated by applying molecular simulations, and the results were found to be accurate. The geometrical optimization and energy gap of the hit compound were calculated by the density functional theory (DFT). Then, ADMET was performed on this hit compound for drug-like features and toxicity. Out of 59 compounds, eight ligands were found active after the 3D-QSAR study. After that, molecular docking was performed on the active compounds F72, F52, F54, F29, F37, F38, F25, and F29, which were recognized as potential targets, and the docking results showed that compound F52 (also an FDA-approved drug) was the best hit. F52 was found to be the best hit against liver cancer cell lines HCC and HepG2. This study would be helpful for early drug discovery optimization and lead identification.

Computational insights into the redox properties and electronic structures of [Tc=O]3+ complexes: Implications for 99mTc-radiopharmaceuticals.

Technetium-99m plays a pivotal role in nuclear medicine, offering unique IMAGING capabilities due to its favorable physical and chemical properties. This study investigates the redox behavior and electronic structures of three representative Tc(V) oxo complexes, [TcO(HMPAO)], [TcO(Bicisate)], and [TcO(DMSA)2]-, using computational techniques. Employing relativistic density functional theory with the Zero-Order Regular Approximation (ZORA), we analyze singlet-triplet energy gaps, Gibbs free energy changes, and redox potentials in neutral and acidic environments. The results highlight the significant influence of co-ligands on the electronic stabilization of complexes and their tendencies toward reduction and protonation. The findings also elucidate the role of Jahn-Teller distortions in shaping the redox properties of the studied complexes. Redox potential trends indicate enhanced reducibility in complexes with sulfur-based ligands, impacting their clinical utility. This study provides valuable insights into the design and optimization of technetium-based radiopharmaceuticals, emphasizing their stability and behavior under physiological conditions.

Electronic band evolution between Lieb and kagome nanoribbons

We investigate the electronic properties of nanoribbons made out of monolayer Lieb, transition, and kagome lattices using the tight-binding model with a generic Hamiltonian. It allows us to map the evolutionary stages of the interconvertibility process between Lieb and kagome nanoribbons by means of only one control parameter. Results for the energy spectra, the density of states, and spatial probability density distributions are discussed for nanoribbons with three types of edges: straight, bearded, and asymmetric. We explore for different nanoribbon terminations: (i) the semiconductor-metallic transition due to the interconvertibility of the Lieb and kagome lattices, (ii) the effect of both nanoribbon width and inclusion of the next-nearest-neighbor hopping term on the degeneracy of the quasi-flat states, (iii) the behavior of the energy gap versus the nanoribbon width, (iv) the existence and evolution of edge states, and (v) the nodal spatial distributions of the total probability densities of the non-dispersive states.

Thiophene engineering of near-infrared D-π-A nano-photosensitizers for enhanced multiple phototheranostics and inhibition of tumor metastasis.

Phototherapy including photothermal therapy (PTT) and photodynamic therapy (PDT) is widely used for cancer treatment because of its non-invasiveness, spatiotemporal controllability, and low side effects. However, the PTT and PDT capabilities of photosensitizers (PSs) compete so it's still a crucial challenge to simultaneously enhance the PDT and PTT capabilities of PSs. In this work, donor-π-acceptor (D-π-A)-based boron dipyrromethene (BODIPY) dyes were developed via molecular engineering and applied for enhanced phototherapy of triple-negative breast cancer. With thiophene engineering and iodine addition, D-π-A BDP dyes possessed a low energy gap between the singlet and triplet states (ΔES1-T1). After the BDP dyes were prepared into nanoparticles (NPs), the BDP4 NPs showed increased generation of type I and II reactive oxygen species (ROS) as well as a high photothermal conversion efficiency (44%). Furthermore, folate (FA)-modified BDP4 NPs achieved high tumor targeting via near-infrared bioimaging. With these advantages, BDP4 NPs with FA achieved total tumor eradication and tumor metastasis suppression via a single injection and 808nm laser irradiation. This work provided a rational design of D-π-A PSs for simultaneously enhancing their photodynamic and photothermal performance, achieving efficient cancer therapy.

Bonding Features of Period 3 and Period 1 Two-Dimensional Superatoms.

Despite being studied for almost two centuries, aromaticity has always been a controversial concept. We previously proposed a unified aromatic rule for π-conjugated systems by two-dimensional (2D) superatomic-molecule theory, where benzenoid rings are treated as period 2 2D superatoms (3π-◊N, 4π-◊O, 5π-◊F, 6π-◊Ne) and, further, bond to form 2D superatomic molecules. Herein, to build a 2D periodic table, we further extend the theory to period 3 (7π-◊P, 8π-◊S, 9π-◊Cl, 10π-◊Ar) and period 1 (1π-◊H, 2π-◊He) elements. Various polycyclic π-conjugated species, namely, C18H16, C14H12, C18H14, [C21H15]-, and C2B4H4, are treated as ◊Cl2, ◊Cl◊F, ◊S◊F2, ◊P◊F3, and ◊H2 superatomic molecules, respectively, where each 2D superatom achieves π electronic shell-closure via superatomic lone pairs and/or two supercenter-two electron (2sc-2e) bonds. Due to the special π electron arrangement and small superatomic orbital energy gaps, period 3 superatoms engage in novel DD, PD orbital interactions and PD, SD2 hybridizations. This work replenishes the 2D periodic table and their bonding rules.

Optical properties of polyvinyl alcohol-glass waste powder composites

This study investigates the effect of glass waste powder content on the UV–Vis spectroscopy of polyvinyl alcohol (PVA). The glass powder was obtained from the waste of fluorescent tubes. The solution casting method was utilized to prepare PVA- glass composite films by adding glass powder with 10, 20, 30, and 40 wt. %. UV–Vis absorption spectra of PVA- glass samples were recorded in the range 220–1100 nm. The optical parameters were calculated as follow: absorbance, absorption coefficient, transmittance, refractive index, extinction coefficient, dielectric constant, and imaginary dielectric constant. Based on the XRD results, it is revealed that the PVA become more amorphous with increasing amount of glass waste. UV–Vis spectroscopy studies demonstrated that, for all samples, the absorbance, absorption coefficient, extinction coefficient, and Ei increases with the increase in the amount of glass waste. On the other hand, transmittance decreases with increasing amount of glass waste. The change of the studied properties with wavelength depends strongly on the amount of glass waste powder. At visible region, the transmittance is stable with increasing wavelength for samples containing 20, 30 and 40%. Glass waste, while the pure sample and the sample containing 10% glass waste, the transmittance increases with the wavelength. On the other hand, the absorbance and absorption coefficient for all samples decreases rapidly up to a specific wavelength and then the change is very slight at longer wavelengths. Also, the increase of extinction coefficient and imaginary dielectric constant with wavelength is related to the amount of glass powder added. The change of dielectric constant and refractive index with wavelength depends on the amount of the filler, where the pure and the sample filled with 10% glass powder show normal dispersion, while the other samples show anomalous dispersion. Finally, the pure sample had the highest energy gap (5.7 eV) while the sample containing 30% glass powder had the lowest value (4.8 eV). Through this study, it become possible to change the optical properties of PVA by adding glass waste powder, which allows the possibility of benefiting from the new composites to be used in different applications according to their response to different wavelengths. From an economic and environmental point of view, these wastes can be utilized instead of being thrown away by reusing them as polymer fillers, taking into consideration the change in the optical properties of the matrix polymer.