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The current study involves the synthesis of two azomethine compounds, (E)‐2‐((6‐nitrobenzo[d][1,3]dioxol‐5‐yl)methylene)amino)phenol (2AP6NO) and (E)‐2‐((4‐ethylbenzylidene)amino)phenol (2AP4ETH), as well as their theoretical investigations. The synthesized azomethine compounds were then characterized by combustion analysis (CHN), FT‐IR, NMR (1H and 13C), and single crystal X‐ray diffraction (SC‐XRD) analysis. The SC‐XRD study confirmed the enol tautomeric form of 2AP6NO as well as 2AP4ETH. The strong and comparatively weak intermolecular interactions were elaborated by Hirshfeld surface analysis. For both compounds, intermolecular interaction energies between the pair of molecules, energy framework, and void analysis were calculated to visualize the three‐dimensional topology of the crystal packing. Additionally, quantum chemical computations were also utilized to study the optical and nonlinear optical (NLO) response. The molecular geometries were optimized at the M06‐2X/6‐311G* method and equated to their respective experimental counterparts. The third‐order NLO polarizabilities were also calculated at the same level of theory. The calculated average third‐order NLO polarizabilities were 62.55×10−36 esu and 55.08×10−36 esu, respectively, predicting the modest behavior of the above compounds when displaying NLO properties. [ABSTRACT FROM AUTHOR]

Summary: Research on perovskite materials is an emerging trend from the last decade in order to improve the precision, stability, validity, consistency and reproducibility of reported perovskite materials and structures. These efforts are very much successful in advancing the composition, solvent, interface, and structure engineering leading toward the record efficiency value of 25.4%. However, the device instability has limited the practical applications of the hybrid perovskite solar cell. This review provides an up‐to‐date summary of the developments to resolve these issues with the uses of different synthesis routes and materials to obtain a stable ABX3 type structure of the perovskite materials. This review also comprehend the effects of electron transport layer on hysteresis phenomenon and long term stability with an outlook on current challenges and further development. Furthermore, a comprehensive discussion on the crystal structure, energy level, absorption coefficient, degradation and chemical bonding in perovskite solar cell materials is also included. Finally, a brief future outlook for perovskites solar cells is discussed. [ABSTRACT FROM AUTHOR]

In the present study, we report synthesis, characterization, structural and theoretical studies of two copper(II) complexes, [Cu(py)2(L1)2] (1) and [Cu(phen)(Ac)2-Cu2(Ac)4]n (2), and a nickel(II) complex, [Ni(bipy)(L)(Ac)] (3), where py = pyridine, L1 = 3,5-dichloro-2-hydroxybenzaldehyde, phen = 1,10-phenanthroline, Ac = acetate ion, bipy = 2,2'-bipyridine and HL = 4-bromo-2-(Z)-(naphthalene-2-ylimino)methyl) phenol. The new complexes were fully characterized using microanalysis, FAB-mas (m/z), FT-IR, UV-Vis and fluorescence spectra, X-band EPR spectroscopy and then by single crystal X-ray diffraction studies. X-ray studies of 1 and 3 revealed distorted octahedral geometries. Complex 2 is a coordination polymer built by an octahedral copper unit Cu(phen)(Ac)2 alternating with paddle wheel species Cu2(Ac)4, located on a crystallographic center of symmetry, where an acetate anion bridges the two crystallographic independent copper ions. The fluorescence intensities and quantum yields of 1 and 2 were found to be more compared to 3. The preliminary tests in the potential application for theoretical biological activities of compounds have also been studied. Furthermore, we also performed quantum chemical calculations to get insights into the structure-property relationships of the synthesized complexes. The quantum chemical calculations were used for theoretical calculations of linear polarizability and third-order nonlinear optical polarizability (γ) for 1, 2 and 3. Besides this, the theoretical calculations, including the analysis of frontier molecular orbitals and electrostatic potential diagrams, are used to highlight the theoretical aspects of metal to ligand charge transfer (MLCT) processes in the studied complexes. [ABSTRACT FROM AUTHOR]

Using density functional theory (DFT) methods, we shed light on the structural, optical, electronic, and nonlinear optical (NLO) properties of three derivatives of 9,12-diiodo-1,2-dicarba-closo-dodecaborane(12) (C2H10B10I2). The DFT and time-dependent DFT methods are considered very precise and practical to optimize the ground and excited state geometries, respectively. A vibrant intramolecular charge transfer from highest occupied molecular orbitals (HOMOs) to the lowest unoccupied molecular orbitals (LUMOs) was observed in all compounds. The geometrical parameters of the experimental crystal structure, i.e. bond lengths/angles, have been successfully reproduced. The HOMO and LUMO energies, as well as their energy gaps (Eg), were also calculated and compared with each other for all derivatives. The effect of attached groups on electronic, optical, and NLO properties along with detailed structure-property relationship was discussed. For NLO response, the CAM-B3LYP functional along with relatively larger basis set 6-31+G** (for hydrogen, carbon, boron, and oxygen atoms) and LANL2DZ (for iodine atoms) have been used to optimize the compounds at ground states. The calculation of second-order NLO polarizabilities (βtot) shows that compounds 2 and 3 possess the βtot amplitudes of 3029 and 4069 a.u., respectively, with CAM-B3LYP method that are reasonably larger than similar prototype molecules. Owing to their unique V-shapes, the nonlinear anisotropy values are found to be 0.63, 0.34, and 0.44 for compounds 1–3, respectively, which show the significant two-dimensional character of these compounds. Thus, the NLO amplitudes as well as the nonlinear anisotropies indicate that the above-entitled compounds are good contenders for optical and NLO applications. [ABSTRACT FROM AUTHOR]

Pyrazole compounds are gaining noteworthy attention in our daily life from better biological active to the semiconducting materials. Present work deals in depth study of indigenously synthesized pyrazole compound, i.e., 2-[(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)methylidene]indan-1,3-dione ( DMPI ) with respect to the structural, electronic, optical and charge transport properties. The ground and excited state geometries were optimized by applying density functional theory (DFT) and time dependent DFT, respectively. The frontier molecular orbitals (FMOs) have been spotlighted. The comprehensible intra-molecular charge transfer (ICT) from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) was observed. The absorption and emission wavelengths were studied at the TD-B3LYP/6-31G** level of theory. The total and partial density of states (T/PDOS) has been studied to understanding the contribution of different states in the electronic properties. The ionization potentials (IP), electron affinities (EA), reorganization energies, transfer integrals, intrinsic mobility and structure-property relationship have been discussed intensively. The smaller hole reorganization energy and superior transfer integral values resulting improved hole intrinsic mobility than the electron ones is revealing that DMPI would be better hole transport material. [ABSTRACT FROM AUTHOR]

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C9H6N2S, triclinic, P1̄ (no. 2), a = 3.9497(4) Å, b = 9.0268(13) Å, c = 12.2935(16) Å, V = 431.37(10) Å3, Z = 2, Rgt(F) = 0.0496, wRref(F2) = 0.0747, T = 296(2) K. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two new Schiff bases were prepared and characterized through UV/VIS, FTIR, NMR and XRD analysis. • DFT and Hirshfeld analysis were carried out to check the different theoretical aspects. • In-vitro and In-silico enzyme inhibition studies were conducted against AChE, BChE and α -glucosidases. The current project was planned to access the enzyme inhibition potential of the synthesize imines; (E)-2-(2-hydroxy-4,5-dimethoxybenzylideneamino)benzonitrile 1 and (E)-2-(((3-hydroxy-4-methylphenyl)imino)methyl)-4-methoxyphenol 2 by the reported protocol of our continuous research and also assess their theoretical function in term of in silico action. The structural characterization of imines was done through advanced techniques i.e., FTIR, 1H NMR, 13C NMR, and UV spectroscopy. Moreover, a single X-Ray diffraction technique (SCXRD) was employed for real structural identification of imines dimensions, which revealed that compound 1 has a triclinic crystal system although 2 has a monoclinic one. A 2D fingerprint plot and Hirshfeld surface analysis (HS) was employed in the crystalline assembly of compounds to check intermolecular contacts and also their degree of contributions. Both compounds were optimized by B3LYP functional mode using a certain basis set (6-31G). The practical data (XRD) and theoretical data (DFT) of both molecules were compared and found between a sound coherence. Molecular docking studies in term of in silico assessment were conducted against enzymes of the esterase and alpha-glucosidase family. The docking outputs give a forecast about compounds that could be employed as protein inhibitors against analyzed protein surfaces. [ABSTRACT FROM AUTHOR]

In the present study, we use a dual approach comprising of experimental and computational techniques to report the syntheses, characterizations (1H NMR, 13C NMR, FT-IR, UV–visible spectroscopy and X-ray structure determination) and theoretically evaluated the third order NLO response properties of the new organic compounds; 1-((E)-(2-methoxy-4-nitrophenylimino)methyl)naphthalen-2-ol hydrate (HL1), (E)- N -(ethoxy(2,3-dichlorophenyl)methyl))-2-methoxy-4-nitrobenzenamine(L2) and copper(II) complex [Cu(L3)(py)] of (E)- N '-(3,5-dichloro-2-hydroxybenzylidene)benzohydrazide(H 2 L3). The HL1 and L2 were crystallized in the triclinic system of the space group P-1 with two molecules in the unit cell, whereas complex [Cu(L3)(py)] was crystallized in the monoclinic system in the space groups P2 1 / c with eight molecules in the unit cell. The thermal properties (DSC and TG-DTG analysis) of these compounds were also investigated. State of the art quantum computational methods are performed at molecular and bulk levels to get structure-property relationships from molecule to materials. For HL1, L2 and complex [Cu(L3)(py)], their isotropic (anisotropic) values are found to be 55.46 × 10−24 esu (71.69 × 10−24 esu), 44.67 × 10−24 esu (26.92 × 10−24 esu) and 60.73 × 10−24 esu (69.71 × 10−24 esu), respectively. The differences in isotropic and anisotropic values are 16.23 × 10−24 esu, 17.75 × 10−24 esu and 9.00 × 10−24 esu, respectively. The NLO response properties including third-order polarizability (γ) are calculated using density functional theory (DFT) methods. The calculated γ amplitudes for the synthesized HL1, L2 and complex [Cu(L3)(py)] are found to be 801.54 × 10−36, 77.81 × 10−36 and 311.17 × 10−36 esu, respectively. These γ amplitudes of HL1, L2 and complex [Cu(L3)(py)] are about 44, 4 and 17 times larger than that of standard para -nitroaniline (PNA, a prototype NLO molecule), respectively, which show the potential of these compounds as efficient NLO materials. Their electronic parameters and NLO properties were also evaluated using TD-DFT calculations. The HL1, L2 and complex [Cu(L3)(py)] showed maximum absorptions with oscillator strengths of 0.749, 0.393 and 0.368 at 2.751 3.476 and 3.214 eV, respectively. Image 1 • Syntheses and characterizations of new organic compounds and Cu(II) complex. • The electronic structures were studied by X-ray crystallography. • The DFT calculations showed the good NLO response properties. • The FMOs and MEPs were used to reveal structure-property relationship. • NMR, FT-IR and UV–Vis spectral analysis were carried out. [ABSTRACT FROM AUTHOR]

The transition metal complexes are playing the crucial role in advancement of modern chemical science. In the present study, we synthesized the Pd(II) complex [Pd 2 (C 5 H 5 F 3 N 2) 2 (C 5 H 4 F 3 N 2) 2 Cl 2 ]·3(C 2 H 6 O), 1 with 3-Methyl-5-(trifluoromethyl) pyrazole ligand. The complex 1 has been characterized by IR spectroscopy, elemental analysis and X-ray crystallography. The complex 1 crystallizes in triclinic space group P -1. Moreover, density functional theory (DFT) methods are successfully used not only to study the optical and nonlinear optical (NLO) properties of complex 1 but also to design its potential derivatives with Ni(II) and Pt(II) metals as complexes 2 and 3 , respectively. The interaction energies are calculated for optimized complexes that are found to be −400, −524.41 and −504.16 kcal/mol for complexes 1 , 2 and 3 , respectively. The calculations for third-order nonlinear optical polarizability (γ) show that the average γ amplitudes for compounds 1 , 2 and 3 are found to be 79.89 × 10−36, 71.24 × 10−36 and 102.09 × 10−36 esu, respectively. The γ amplitudes of compounds 1 , 2 and 3 are about 4 times, 3 times and 5 times larger than that of para -nitroaniline (p NA), which is a prototype NLO molecule, respectively. The calculations of UV–Visible spectra show that the maximum absorption wavelength for complex 3 is around 260 nm with a significantly larger oscillator strength, which is about 4 times larger than the absorption spectra of complexes 1 and 2. The analysis of FMOs shows the ligand to metal intramolecular charge transfer (LMCT) process which might be the reason of larger NLO response properties in complex 3. Additionally, the calculations of global chemical reactivity descriptors indicate that the complexes are thermally and kinetically stable. Thus, we believe the present study will intrigue the scientific community to explore the designed complexes for optical and NLO applications. [ABSTRACT FROM AUTHOR]

Graphical abstract We use a dual approach comprising of experimental and computational techniques to report the syntheses and characterizations of two novel nickel (II) [Ni(L) 2 ] (1) and copper (II) [Cu(L) 2 ] (2) coordination complexes, which are made through the coordination of 1-(E -(2, 4-dibromophenylimino) methyl) naphthalene-2-ol (HL) ligand. Several modern techniques including experimental electronic spectroscopy, single crystal X-ray crystallography and quantum computational methods are used to characterize the isolated coordination compounds. Both the complexes display a square planar trans-[MN 2 O 2 ] coordination geometry (Figure 1), whose central M (II) atoms lie on the centre of symmetry. State of the art quantum computations are performed at molecular and bulk levels to get structure-property relationships from molecule to materials. The molecular nonlinear optical (NLO) response properties including third-order polarizability (γ) are calculated using density functional theory (DFT) methods. The calculated γ amplitudes for the synthesized [Ni(L) 2 ] (1) and [Cu(L) 2 ] (2) complexes are found to be 444.09 × 10−36 and 567.03 × 10−36 esu, respectively. Highlights • Design and synthesis of Schiff base (HL) ligand and its metal (II) complexes. • Single crystal X-ray crystallography analysis. • Dual approach comprising of experimental and computational techniques. • Nonlinear optical (NLO) response properties. • Optoelectronic properties. Abstract In the present study, we use a dual approach comprising of experimental and computational techniques to report the syntheses and characterizations of two novel nickel (II) [Ni(L) 2 ] (1) and copper (II) [Cu(L) 2 ] (2) coordination complexes, which are made through the coordination of 1-(E -(2, 4-dibromophenylimino) methyl) naphthalene-2-ol (HL) ligand. Several modern techniques including experimental electronic spectroscopy, single crystal X-ray crystallography and quantum computational methods are used to characterize the isolated coordination compounds. Both the complexes display a square planar trans-[MN 2 O 2 ] coordination geometry, whose central M (II) atoms lie on the centre of symmetry. Complexes [Ni(L) 2 ] (1) and [Cu(L) 2 ] (2) crystallize in the monoclinic system of the space groups P 21/ c with a = 9.307(4)Å, b = 12.242(4)Å, c = 13.823(4)Å, α = 90°, β = 105.262(10)°, γ = 90° and Z = 2 for complex (1), a = 9.171(5) Å, b = 12.507(8) Å, c = 13.666(8) Å, α = 90°, β = 103.823(15)°, γ = 90°, and Z = 2 for complex (2). The ligand (HL) is coordinated as monobasic bidentate with N and O donor groups suitably oriented for forming two six membered chelate rings. State of the art quantum computations are performed at molecular and bulk levels to get structure-property relationships from molecule to materials. The molecular nonlinear optical (NLO) response properties including third-order polarizability (γ) are calculated using density functional theory (DFT) methods. The calculated γ amplitudes for the synthesized [Ni(L) 2 ] (1) and [Cu(L) 2 ] (2) complexes are found to be 444.09 × 10−36 and 567.03 × 10−36 esu, respectively. These γ amplitudes of [Ni(L) 2 ] (1) and [Cu(L) 2 ] (2) complexes are about 21 and 27 times larger than that of standard para -nitroaniline (PNA, a prototype NLO molecule), respectively, which show the potential of these complexes as efficient NLO materials. Additionally, several important optical parameters including dielectric function, reflective index, reflectivity, conductivity and loss function are calculated at bulk level using ab initio methods within periodic boundary conditions (PBC). The obtained results indicate that both coordination complexes has good optical and NLO properties, which may render the above entitled complexes as efficient candidates for optoelectronic and NLO device fabrications. [ABSTRACT FROM AUTHOR]

The naphthalene is good contender which is intensively used in organic semiconductors. Here, three new naphthalene based compounds were prepared by the condensation of 1,5-diaminonaphthalene, 5-methylfurfural and 5-nitrofurfural. The prepared Schiff base compounds were analyzed by Fourier Transmission Infrared spectroscopy (FTIR), UV–vis spectroscopy (UV-vis) and single crystal x-ray studies. The compound 1 was obtained in P21/n crystal packing. A comprehensive electronic structure-property relationship was elucidated through the prism of frontier molecular orbitals (FMOs). The calculated absorption wavelengths at TD-B3LYP/6-31G** level displayed reasonably decent agreement to the experimental data. The effect of electron donating groups and electron withdrawing groups was discussed on optoelectronic properties, ionization potentials, electron affinities and reorganization energies. On the basis of transfer integrals and intrinsic mobility nature of the charge transport of compound 1 was discussed. The electron injection, electronic coupling constant and light harvesting efficiency revealed that the studied Schiff base compounds would be good contestants to be used in dye-sensitized solar cells. Compounds 2 and 3 have 8 and 6 times larger β tot than that of para-nitro aniline revealing that these materials might be good for nonlinear optics as well. [ABSTRACT FROM AUTHOR]

The recent COVID-19 outbreak caused by the novel coronavirus SARS-CoV-2 has an immense impact on global health and economy. Although vaccines are being used, urgent need of drugs based on natural products with high efficacy and safety is a pressing priority. Quinoline alkaloids are well known for their therapeutic action against malaria; initially, it was tried against Coronaviruses. It is a basic vital scaffold to design drugs with required biological and pharmacological activities. In this present study, a new quinoline compound was synthesized and characterized by spectroscopy techniques. Crystal structure was established by SCXRD analysis and data is used as an input to perform various computations. Additionally, using state-of-the-art quantum computational techniques, the geometry optimization and calculation of UV–Vis spectrum of 2F6M3CQ were performed at B3LYP/6-311G* level of theory. The optimized molecular geometric parameters as well as UV–Vis spectrum values are found to be in good agreement with their respective experimental results. The visualization of 3-D plots of FMO and MEP indicated the structure and reactivity trends of 2F6M3CQ molecule. Molecular docking methods were utilized to find the drug ability of 2F6M3CQ with Mproprotein of SARS-CoV-2. There were many intermolecular interactions between Mpro protein and 2F6M3CQ molecule which lead to good binding energy (−5.5 kcal/mol) between them which was found to be better than the binding energy of chloroquinine molecule (−4.5 kcal/mol) as studied under same docking protocols. Finally, drug likeness and ADME properties of 2F6M3CQ were also analyzed. There is no violation found for RO5 in our 2F6M3CQ compound. ADME analysis shows drug like properties of compound 2F6M3CQ which predicts that it might be a potential candidate for inhibition of SARS-CoV-2. [Display omitted] • Synthesis of functionalized 2- formyl-6-methoxy-3-carbethoxy quinoline from Vilsmeier - Haack heterocyclization of β –anilinocrotonate. • Synthesized compound was grown as single crystal in ethanol medium and SCXRD of the crystal has been done.in ethanol medium and SCXRD of the crystal has been done. • The title compound was also characterized by UV–Vis, FT- IR, and NMR Studies. • Molecular geometry of the compound was theoretically explored using DFT and compared with experimental results. • Computational methods were utilized to find the docking ability of the compound against the main protease of SARA-CoV-2. [ABSTRACT FROM AUTHOR]

• Synthesis growth and molecular interaction of organic nonlinear optical single crystals of (E)-N′-(2,3-dimethoxybenzylidene)−4-fluorobenzohydrazide (DMB-FBH) were discussed. • X-ray single-crystal diffraction analysis confirmed the structure. • Vibrational analysis and various electronic properties of the compound were studied using density functional theory (DFT) calculations. • Hirshfeld surface analyses and fingerprint plots confirmed the O...H, N...H, C...C and C...H intermolecular hydrogen bonds interaction. • UV–visible and the fluorescence emission spectra of the DMB-FBH in aqueous solutions were recorded. • Third order nonlinear optical susceptibility (χ3) of DMB-FBH was determined by Z-scan measurement. Organic nonlinear optical single crystals of (E)-N′-(2,3-dimethoxybenzylidene)-4-fluorobenzohydrazide (DMB-FBH) were synthesized and grown using slow evaporation crystallization from ethanol solution. The single crystal X-ray diffraction scattering revealed that the DMB-FBH crystallised in the tetragonal crystal system with a centro symmetric space group of I 4 1 /a. The crystallographic bond lengths and bond angles were compared with the values generated from optimized molecular geometry based on quantum chemical calculations. The functional group vibrations were identified theoretically by density functional theory with B3LYP 6–311 G (d,p) basis set using Gaussian 09 software package and their vibrations were compared with the experimental FT-IR spectra. The UV-visible and the fluorescence emission spectra of the DMB-FBH in aqueous solutions were recorded. The HOMO-LUMO energy level pictogram addressed the intramolecular charge transfer (ICT) interaction between donor and acceptor moieties and their impact on the energy gap was determined. Different interactions such as O···H, N···H, C···C and C···H in DMB-FBH were quantified via fingerprint plots and these results were compared with that of similar structure. The detailed molecular docking simulation was carried out with M. tuberculosis protein [PDB ID:2 × 22]. The third order nonlinear optical susceptibility (χ3) of DMB-FBH was confirmed experimentally by Z-scan method and their conversion efficiency was higher than the other hydrazones derivatives. In short, this work discusses the crystal structure, identification and quantification of the molecular interactions, thermal, antimycobacterial and optical properties of new hydrazone derivative. Energy frameworks (left) coloumb dispersion (center) and total energy (right) of DMB-FBH crystal structure. [Display omitted] [ABSTRACT FROM AUTHOR]

Herein, two new thiazole derivatives: ethyl2-(2-benzylidenehydrazinyl)thiazole-4-carboxylate (3) and ethyl2-(2-(2-hydroxybenzylidene)hydrazinyl)thiazole-4-carboxylate (4) were synthesized by cyclization of 1-benzylidenethiosemicarbazide with ethyl bromopyruvate. The synthesis was validated by spectroscopic techniques like FTIR, 1H- NMR, 13C-NMR and chemical structure of title compounds 3 and 4 has been determined using SC-XRD. Ancillary to experimental analysis, DFT calculations with B3LYP/6-311 + G (d,p) level were performed for comparative analysis of FT-IR spectroscopic data, optimized geometry, frontier molecular orbitals (FMOs), natural bond orbital (NBO) analysis and nonlinear optical (NLO) properties. Overall, experimental findings were supported by corresponding DFT computed results. TDDFT calculations were executed at M06/6-311 + G (d,p) level of theory to calculate the vertical electronic transition states. NBO analysis disclosed that intramolecular charge transfer and hyper-conjugative interactions among bonds provide stability to the investigated compounds 3 and 4. The global reactivity parameters calculated from energy of FMOs indicates that 3 and 4 enclose larger softness and fewer hardness values. NLO results of 3 and 4 were observed better than standard molecule recommended the NLO activity of said compounds. We hope that this joint experimental and computational insight may provide new ways for the utilization of title molecules as NLO material for optoelectronic applications. Image 1 • Two novel ethyl 2-(2-(2-substitutedbenzylidene)hydrazinyl)thiazole-4-carboxylate crystals were synthesized. • XRD, 1H NMR, 13C NMR, FT-IR and UV–Vis were performed for the characterization. • Computational study was done at B3LYP/6-311 + G (d,p) level for comparative analysis. • Comparative study reveals a good agreement between experimental and DFT results. • FMOs, NBO analysis and nonlinear optical (NLO) properties were calculated. [ABSTRACT FROM AUTHOR]

Broad band optical limiting action of Cr doped (γ and β)-BBO was demonstrated by Z-scan experiment using first (1064 nm) and second (532 nm) harmonics of Q-switched nanopulsed (9 ns, 10 Hz) Nd:YAG laser. The recorded OA pattern at 532 nm exposes that the dispersed liquids exhibit reverse saturable absorption ascribed due to 2PA process. At 0.05 M Cr doped BBO, peculiar switching of SA (0.63 GW/cm2) to RSA (2.52 GW/cm2) was observed under 532 nm excitation. Increase in 2PA coefficient with on-axis peak intensity and availability of Cr induced near-resonant energy states demonstrate the presence of sequential 2PA (1PA + ESA) process. Interestingly under 1064 nm excitation, Cr doped γ-BBO exhibit 3PA while Cr doped β-BBO possess 2PA process. The addition of Cr has induced transition states in visible and IR region, therefore availability of transition states confirms the involvement of excited ESA process at 1064 nm regime. All the liquids exhibit optical limiting action in which onset optical limiting threshold varies with phase, concentration of Cr and on-axis peak intensity. Comparing the NLA coefficient of Cr doped (γ and β)-BBO in both 532 nm and 1064 nm region, the involvement of trapped state of Cr at 2PA region has improved the absorption coefficient than the real 2PA state of pristine (γ and β)-BBO. Among Cr doped (γ and β)-BBO at 532 nm regime, 0.05 M Cr doped (γ and β)-BBO exhibits low threshold of 0.75 × 1012 W/m2 and 0.57 × 1012 W/m2 respectively. Interestingly at 1064 nm regime, 0.03 M Cr doped (γ and β)-BBO possess better onset limiting threshold of 0.986 × 1012 W/m2 and 2.92 × 1012 W/m2 respectively. Earlier by hydrothermal technique tunability of band structure was achieved by introducing Cr in two different phases of BBO (γ and β) at different concentration (0.01 M, 0.03 M and 0.05 M). Incorporation of Cr without altering the crystal structure of host BBO was confirmed by XRD and Raman analysis. SEM analysis exposes the transformation of nanorod to nanowire (γ-BBO) and irregular platelet to cubic (β-BBO) morphology due to Cr incorporation in BBO. Ground state absorption studies shows Cr doped (γ and β)-BBO possess transition at 532 nm and 1064 nm due to 4A 2g (F) → 4T 1g (F), 4A 2g (F) →4T 2g (F) transition of Cr. Thus by Cr doping in BBO, ESA assisted 2PA and 3PA based broad band optical limiting with higher NLO coefficients was demonstrated successfully. • Cr doped (γ and β)-BBO nanostructures were synthesized by hydrothermal technique. • SEM exposes the transformation of nanorods to nanowire (γ-BBO) and irregular platelet to cubic (β-BBO) morphology. • Under 532 nm excitation, peculiar switching of SA to RSA was observed in 0.05 M Cr doped BBO. • Interestingly under 1064 nm excitation, Cr doped γ-BBO exhibit 3PA while Cr doped β-BBO possess 2PA process. • Cr doped γ-BBO nanostructures exhibit higher NLO coefficient and OLT value than Cr doped β-BBO. [ABSTRACT FROM AUTHOR]

Novel organic third-order nonlinear optical material, 2-Amino-4-picolinium-2-chloro-4-nitrobenzoate (2A4P2C4N) was synthesized and grown into single crystal by slow solvent evaporation method at room temperature. Single crystal X-ray diffraction analysis reveals that the title compound crystallizes in monoclinic crystal system with a centrosymmetric space group of P2 1 /n. From UV–Visible spectrum, the optical transparency and band gap were determined. Thermal stability of the title material was established by thermogravimetry (TG) and differential thermal analysis (DTA) analyses. The third-order nonlinear susceptibility was determined experimentally and it was found to be 2.56 × 10−8 esu. The quantum chemical calculations were performed to analyze Hirshfeld surface, electrostatic potential, HOMO-LUMO and global quantum chemical reactivity descriptors of the titled molecule at B3LYP/6–311++G (d,p) level of theory. A comparative analysis computationally calculated showed that the <γ> amplitude for 2A4P2C4N molecule was found to be three 3 times greater than that of compared para -Nitroaniline (p-NA). Image 1 • 2A4P2C4N crystal was successfully grown by solvent evaporation method. • 2A4P2C4N crystal belongs to monoclinic crystal system with space group, P2 1 /n. • The crystal structure was optimized by DFT with B3LYP/6–311++G (d,p) basis set. • The title crystal was thermally stable up to 178 °C. • The third-order nonlinear susceptibility was found to be 2.56 × 10−8 esu. [ABSTRACT FROM AUTHOR]

A copper (II) malonate complex{[(C 7 H 8 O 2 N) 2 ][Cu(C 3 H 2 O 4) 2 (H 2 O) 2 ]}, 1 has been synthesized and characterized by IR spectroscopy, elemental analysis, TGA/DSC and X-ray crystallography. The X-ray analysis reveals that the complex is anionic species in which copper is coordinated by six oxygen atoms having octahedral coordination geometry that is tetragonally compressed due to Jahn Teller effect. To balance the charge on the complex ion two molecules of 4-carboxybenzeneammonium ions are present as counter ions. The density functional theory methods are applied to explore the linear and nonlinear optical (NLO) properties of 1 using M06 method and 6-31G*/LANL2DZ basis set. The calculated linear molecular polarizability and third-order NLO polarizability of 1 are found to be 43.98 × 10−24 esu and 33.93 × 10−36 esu, respectively, which interestingly better than some standard NLO molecules. To comprehend more understanding, the optical properties from molecule to material levels, we also calculated the optical properties (dielectric function, refractive index and absorption spectrum) in solid-state at bulk-level within periodic boundary conditions (PBC). The calculated optical properties show that the complex 1 possesses static dielectric function and refractive index values of 2.0 and 1.4, respectively. The absorption wavelength from 3 eV to 6 eV illustrates that the complex 1 has strong absorption and larger reflectivity values in UV region, which may be potential for using complex 1 as coating materials. It is credible that the synthesized complex 1 may possess reasonable potential for its application as optical and NLO material. Unlabelled Image • Synthesis of Copper malonate complex {[(C 7 H 8 O 2 N) 2 ][Cu(C 3 H 2 O 4) 2 (H 2 O) 2 ]} • Experimental characterization by single crystal X-ray analysis, IR, TGA/DSC and CHNS analysis • The quantum chemical study of linear and nonlinear optical properties of 1 • The reasonably large NLO polarizability of 1 is found to be 33.93 × 10−36 esu. • The optical properties of complex 1 were also determined in solid-state within PBC. [ABSTRACT FROM AUTHOR]