Syntheses, crystal structures, and quadratic nonlinear optical properties in four “push–pull” diorganotin derivatives

Preparation of seven-coordinated hypervalent tin(IV)-fused azobenzene and applications for stimuli-responsive π-conjugated polymer films

Heavy atoms can form highly coordinated states, and their optical properties have attracted much attention. Recently, we have demonstrated that a reversible coordination-number shift of hypervalent tin(IV) from five to six can provide predictable hypsochromic shifts in light absorption and emission properties in small molecules and a π-conjugated polymer film. Herein, we show the preparation of seven-coordinated tin and reveal that the binding constant of the seven coordination with ethylenediamine (EDA, K = 2900 M-1) is 200 times higher than that of six coordination with propylamine (PA, K = 14 M-1) owing to the chelate effect. Moreover, reversible vapochromism of the π-conjugated polymer film was observed upon exposure (λabs = 598 nm and λPL = 697 nm) and desorption (λabs = 641 nm and λPL = 702 nm) of EDA vapor. Furthermore, as a unique demonstration, the thermochromic film was prepared by fixing the seven coordination as the initial state using 1,10-phenanthroline. These optical variations are predictable by quantum chemical calculations. Our findings are valuable for the development of designable and controllable stimuli-responsive materials focusing on the inherent properties of the elements.

Mitochondria-Targeted Luminescent Organotin(IV) Complexes: Synthesis, Photophysical Characterization, and Live Cell Imaging

Five fluorescent ONO donor-based organotin(IV) complexes, [Sn^IV(L^1-5)Ph₂] (1-5), were synthesized by the one-pot reaction method and fully characterized spectroscopically including the single-crystal X-ray diffraction studies of 2-4. Detailed photophysical characterization of all compounds was performed. All the compounds exhibited high luminescent properties with a quantum yield of 17-53%. Additionally, the results of cellular permeability analysis suggest that they are lipophilic and easily absorbed by cells. Confocal microscopy was used to examine the live cell imaging capability of 1-5, and the results show that the compounds are mostly internalized in mitochondria and exhibit negligible cytotoxicity at imaging concentration. Also, 1-5 exhibited high photostability as compared to the commercial dye and can be used in long-term real-time tracking of cell organelles. Also, it is found that the probes (1-5) are highly tolerable during the changes in mitochondrial morphology. Thus, this kind of low-toxic organotin-based fluorescent probe can assist in imaging of mitochondria within living cells and tracking changes in their morphology.

Sn6 and Na4 Oxo Clusters Based Non-centrosymmetric Framework for Solution Iodine Absorption and Second Harmonic Generation Response

A three-dimensional non-centrosymmetric cluster organic framework has successfully been built from the {Sn₆} and {Na₄} cluster units via the oxalate ligand, which belongs to the first 3D framework containing different cluster units in the field of tin-oxo clusters. Besides the interesting structural characteristics, the obtained 3D framework not only can efficiently adsorb the iodine molecules but also displays the second harmonic generation response under the 1064 nm Q-switch laser.

State of the Art of Boron and Tin Complexes in Second- and Third-Order Nonlinear Optics §

Boron and tin complexes have been a versatile and very interesting scaffold for the design of nonlinear optical (NLO) chromophores. In this paper we present a wide range of reports since the 1990s to date, which include second-order (e.g., second harmonic generation) and third-order (e.g., two-photon absorption) NLO properties. After a short introduction on the origin of the NLO response in molecules, the different features associated with the introduction of these inorganic motifs in the organic-based NLO materials are discussed: Their effect on the accepting/donating capabilities of the substituents, on the efficiency of the π-conjugated linkage, and on the topology of the chromophores which can be tuned from the first generation of “push-pull” chromophores to more sophisticated two- or three-dimensional architectures.

Fluorescent biogenic Schiff base compounds of dimethyltin

Fluorescent biogenic Schiff base compounds of dimethyltin featuring distinct coordination sphere in solid and solution phase.

Theoretical studies of organotin(IV) complexes derived from ONO-donor type schiff base ligands

In this work a molecular modeling study was carried out based on a series of organotin(IV) derivatives which were complexed with ONO-Donor type Schiff base ligands to build up a statistical data pool for researchers. For this purpose, various properties of the selected complexes such as energies, band gaps, chemical reactivity descriptors, polarizabilities, geometric parameters, (1)H-NMR, (13)C-NMR chemical shifting values were obtained through density functional theory using B3LYP, CAM-B3LYP, TPSSTPSS, TPSSh, HCTH, wB97XD, and MN12SX functionals. Empirical dispersion corrections were incorporated for some functionals and solvent effects were also taken into account through applying polarizable continuum model (PCM). (1)H-NMR, (13)C-NMR chemical shifts were calculated via linear regression analysis using either gauge invariant atomic orbital (GIAO) or continuous set of gauge transformations (CSGT) methods. While structural properties were being explored, quantitative effects of utilized functionals and empirical dispersion corrections over calculated properties were shown in detail.

Syntheses, structures, and1H,13C{1H} and119Sn{1H} NMR chemical shifts of a family of trimethyltin alkoxide, amide, halide and cyclopentadienyl compounds

The synthesis and full characterization by Nuclear Magnetic Resonance (¹H,¹³C{¹H} and¹¹⁹Sn{¹H}) of eleven Me₃SnX complexes in six common organic solvents is presented.

(E)-2-{[4-(Di-methyl-amino)-benzyl-idene]amino}-5-nitro-phenol

The title Schiff base compound, C₁₅H₁₅N₃O₃, crystallizes with two mol­ecules (A and B) in the asymmetric unit. Each mol­ecule adopts an E conformation around the C= N imine bond. The two mol­ecules have minor differences in their conformations. In mol­ecule A, the dihedral angle between the nitro group and its benzene ring is 2.1 (2)° and that between the two benzene rings is 0.88 (7)°, while the corresponding angles for mol­ecule B are 5.7 (1) and 2.45 (6)°, respectively. In each mol­ecule, there is an intra­molecular O—H⋯N hydrogen bond. In the crystal, inversion-related mol­ecules are linked via O—H⋯O hydrogen bonds forming A–A and B–B dimers. These dimers are linked via C—H⋯O hydrogen bonds involving the nitro O atoms, forming A–A–A and B–B–B slabs that lie parallel to one another and to (010).

Synthesis, Spectroscopic Characterization, and Biological Activities of Metal Complexes of 4-((4-Chlorophenyl)diazenyl)-2-((p-tolylimino)methyl)phenol

Azo Schiff base complexes of VO(II), Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) have been synthesized from 4-((4-chlorophenyl)diazenyl)-2-((p-tolylimino)methyl)phenol (CDTMP). The nature of bonding and the structural features of the complexes have been deduced from elemental analysis, molar conductance, magnetic susceptibility measurements, IR, UV-Vis,1H-NMR, EPR, mass, SEM, and fluorescence spectral studies. Spectroscopic and other analytical studies reveal square-planar geometry for copper, square-pyramidal geometry for oxovanadium, and octahedral geometry for other complexes. The EPR spectra of copper(II) complex in DMSO at 300 K and 77 K were recorded, and its salient features are reported. Antimicrobial studies against several microorganisms indicate that the complexes are more potent bactericides and fungicides than the ligand. The electrochemical behavior of the copper(II) complex was studied by cyclic voltammetry. All the synthesized compounds can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic conversion efficiency of the synthesized azo Schiff base was found to be higher than that of urea and KDP (potassium dihydrogen phosphate). SEM image of copper(II) complex implies the crystalline state and surface morphology of the complex.

A new Schiff base compound N,N'-(2,2-dimetylpropane)-bis(dihydroxylacetophenone): synthesis, experimental and theoretical studies on its crystal structure, FTIR, UV-visible, 1H NMR and 13C NMR spectra

The Schiff base compound, N,N'-(2,2-dimetylpropane)-bis(dihydroxylacetophenone) (NDHA) is synthesized through the condensation of 2-hydroxylacetophenone and 2,2-dimethyl 1,3-amino propane in methanol at ambient temperature. The yellow crystalline precipitate is used for X-ray single-crystal determination and measuring Fourier transform infrared (FTIR), UV-visible, (1)H NMR and (13)C NMR spectra. Electronic structure calculations at the B3LYP, PBEPBE and PW91PW91 levels of theory are performed to optimize the molecular geometry and to calculate the FTIR, (1)H NMR and (13)C NMR spectra of the compound. Time-dependent density functional theory (TDDFT) method is used to calculate the UV-visible spectrum of NDHA. Vibrational frequencies are determined experimentally and compared with those obtained theoretically. Vibrational assignments and analysis of the fundamental modes of the compound are also performed. All theoretical methods can well reproduce the structure of the compound. The (1)H NMR and (13)C NMR chemical shifts calculated by all DFT methods are consistent with the experimental data. However, the NMR shielding tensors computed at the B3LYP/6-31+G(d,p) level of theory are in better agreement with experimental (1)H NMR and (13)C NMR spectra. The electronic absorption spectrum calculated at the B3LYP/6-31+G(d,p) level by using TD-DFT method is in accordance with the observed UV-visible spectrum of NDHA. In addition, some quantum descriptors of the molecule are calculated and conformational analysis is performed and the results were compared with the crystallographic data.

Chemistry and applications of organotin(IV) complexes of Schiff bases

Schiff bases are the most widely used versatile ligands, able to coordinate many elements and to stabilize them in various oxidation states. Recently, this class of compounds has been employed as models for biological systems, and in control of stereochemistry in six-coordinate transition metal complexes. Recently, the chemistry of organotin(IV) complexes of Schiff bases has also stemmed from their antitumour, antimicrobial, antinematicidal, anti-insecticidal and anti-inflammatory activities. Furthermore, organotin(IV) complexes of Schiff bases present a wide variety of interesting structural possibilities. Both aliphatic and aromatic Schiff bases in their neutral and deprotonated forms have been used to yield adducts and chelates with variable stoichiometry and different modes of coordination. This critical review (>155 references) focuses upon the chemistry and biological applications of organotin(IV) complexes of Schiff bases reported in the past 15 years. Thermal behavior of these complexes is also discussed.

A new salen base 5-(phenylazo)-N-(2-amino pyridine) salicyliden Schiff base ligand: synthesis, experimental and density functional studies on its crystal structure, FTIR, 1H NMR and 13C NMR spectra

A novel Schiff base ligand 5-(phenylazo)-N-(2-amino pyridine) salicyliden is prepared through the condensation of 5-(phenylazo) salicylaldehyde and 2-amino pyridine in methanol at room temperature. The orange crystalline precipitate is used for X-ray crystallography and measuring Fourier transform (FTIR), 1H NMR and 13C NMR spectra. Density functional theory (DFT) calculations at the B3LYP, MPWB1K and B3PW91 levels of theory is used to optimize the geometry and calculate the FTIR, 1H NMR and 13C NMR spectra of the compound. The vibrational frequencies determined experimentally are compared with those obtained theoretically and a vibrational assignment and analysis of the fundamental modes of the compound is performed. We found that the MPWB1K method predicts low vibrational frequencies better than the commonly used B3LYP method. Although the B3PW91 method overestimates the 1H NMR chemical shifts, the values computed at the B3LYP level of theory are in accordance with experimental 1H NMR spectrum. However, both B3LYP and B3PW91 methods tend to overestimate 13C NMR chemical shifts. In addition, a few quantum descriptors of the molecule are calculated and conformational analysis is performed and the result was compared with crystallographic data.

Synthesis, characterization, biological activities of dimethyltin(IV) complexes of Schiff bases with ONO-type donors

Four different dimethyltin(IV) complexes of Schiff bases derived from 2-amino-3-hydroxypyridine and different substituted salicylaldehydes have been synthesized. The compounds, with the general formula [Me(2)Sn(2-OArCH=NC(5)H(3)NO)], where Ar=-C(6)H(3)(5-CH(3)) [Me(2)SnL(1)], -C(6)H(3)(5-NO(2)) [Me(2)SnL(2)], -C(6)H(2)(3,5-Cl(2)) [Me(2)SnL(3)], and -C(6)H(2)(3,5-I(2)) [Me(2)SnL(4)], were characterized by IR, NMR ((1)H and (13)C), mass spectroscopy and elemental analysis. Me(2)SnL(3) was also characterized by X-ray diffraction analysis and shows a fivefold C(2)NO(2) coordination with distorted square pyramidal geometry. H(3)C-Sn-CH(3) angles in the complexes were calculated using Lockhart's equations with the (1)J((117/119)Sn-(13)C) and (2)J((117/119)Sn-(1)H) values (from the (1)H-NMR and (13)C-NMR spectra). The in vitro antibacterial and antifungal activities of dimethyltin(IV) complexes were also investigated.

Synthesis and characterization of di-phenyl-tinIV-salicyliden-ortho-aminophenols: Analysis of in vitro antitumor/antioxidant activities and molecular structures

The one pot reactions carried among salicylaldehyde 1, ortho-aminophenols 2a-2g, and di-phenyl-tin(IV) oxide 3 led to seven di-phenyl-tin(IV) compounds 4a-4g in good yields (97-83%). All compounds were analyzed by IR, 1H, 13C, 119Sn NMR spectroscopy, mass spectrometry and elemental analyses; furthermore, in the case of compounds 4b, 4c, 4e and 4g by X-ray diffraction. Compounds 4a-4g were tested in vitro against six human tumor cell lines U251, PC-3, K-562, HCT-15, MCF-7 and SKLU-1 to assess their in vitro antitumor activity. The results suggest biological specificity towards U251, MCF-7 and SKLU-1 cells at doses below 2.5 microM, which are lower than cis-platin IC50's in the three cell lines. Since the inhibitory concentration values for the series were alike to Ph(2)SnCl(2) is feasible that only the Ph(2)Sn moiety is responsible for those activities, further experiments are under research. Besides, 4a-4g were tested for their antioxidant efficiency in rat brain homogenate showing that 4g is more active (IC50=3.01 microM) than the flavone quercetin (natural antioxidant, IC50=4.11 microM) on inhibition of thiobarbituric acid reactive substances (TBARS). The TBARS activity (IC50) correlates with the ortho-aminophenol substitutions and a linear combination among sigma Hammett, one bond tin coupling constants and tin chemical shifts against the measured IC(50-TBARS) was found. This correlation gave basis that the implied molecular variables can become trackers for the calculation of TBARS inhibitory concentrations in similar systems. Moreover, there seemed to be an inverse structure-response behavior among activities, since the 4g derivative is the less active compound for cytotoxic assays meanwhile it is the best in antioxidant tests.