Structural Characterization and Non-linear Optical Properties of Metal Complexes of Some Donor-Acceptor Substituted N-salicylidene-N' -aroylhydrazine Ligands

The present work deals with the complexation of Schiff bases of aroylhydrazines with various transition metal ions. The hydrazone systems selected for study have long 7I:-delocalized chain in the ligand molecule itself, which get intensified due to metal-to-ligand or ligand-to-metal charge transfer excitations upon coordination. Complexation with metal ions like copper, nickel, cobalt, manganese, iron, zinc and cadmium are tried. Various spectral techniques are employed for characterization. The structures of some complexes have been well established by single crystal X-ray diffraction studies. The nonIinaer optical studies of the ligands and complexes synthesized have been studied by hyper-Rayleigh scattering technique.The work is presented in seven chapters and the last one deals with summary and conclusion. One of the hydrazone system selected for study proved that it could give rise to polymeric metal complexes. Some of the copper, nickel, zinc and cadmium complexes showed non-linear optical activity. The NLO studies of manganese and iron showed negative result, may be due to the inversion centre of symmetry within the molecular lattice.

Phenylethynylarene Based Donor-Acceptor Systems: Design, Synthesis and Photophysical Studies

This thesis Entitled phenylethynylarene based Donor-Acceptor systems:Desigh,Synthesis and Photophysical studies. A strategy for the design of donor-acceptor dyads, wherein decay of the charge separated (CS) state to low lying local triplet levels could possibly be prevented, is proposed. In order to examine this strategy, a linked donor-acceptor dyad BPEPPT with bis(phenylethYlly/)pyrene (BPEP) as the light absorber and acceptor and phenothiazine (PT) as donor was designed and photoinduced electron transfer in the dyad investigated. Absorption spectra of the dyad can be obtained by adding contributions due 10 the BPEP and PT moieties indicating that the constituents do not interact in the ground stale. Fluorescence of the BPEP moiety was efficiently quenched by the PT donor and this was attributed to electron lransfer from PT to BPEP. Picosecond transient absorption studies suggested formation of a charge separated state directly from the singlet excited state of BPEP. Nanosecond flash photolysis experiments gave long-ived transient absorptions assignable to PT radical cation and BPEP radical anion. These assignments were confirmed by oxygen quenching studies and secondary electron transfer experiments. Based on the available data, energy level diagram for BPEP-PT was constructed. The long lifetime of the charge separated state was attributed to the inverted region effects. The CS state did not undergo decay to low lying BPEP triplet indicating the success of our strategy

Crystal Structures and Spectral Aspects of Mixed Ligand Transition Metal Chelates Derived from Aldehyde based ONS Donor Thiosemicarbazones

Thiosemicarbazones have emerged as an important class of ligands over a period of time, for a variety of reasons, such as variable donor properties, structural diversity and biological applications. Interesting as the coordination chemistry may be, the driving force for the study of these ligands has undoubtedly been their biological properties and the majority of the 3000 or so publications on thiosemicarbazones since 2000 have alluded to this feature. Thiosemicarbazones with potential donor atoms in their structural skeleton fascinate coordination chemists with their versatile chelating behavior. The thiosemicarbazones of aromatic aldehydes and ketones form stable chelates with transition metal cations by utilizing both their sulfur and azomethine nitrogen as donor atoms. They have been shown to possess a diverse range of biological activities including anticancer, antitumor, antibacterial, antiviral, antimalarial and antifungal properties owing to their ability to diffuse through the semipermeable membrane of the cell lines. The enhanced effect may be attributed to the increased lipophilicity of the metal complexes compared to the ligand alone.

Synthesis, characterization and physiochemical information, along with antimicrobial studies of some metal complexes derived from an ON donor semicarbazone ligand

Eight new transition metal complexes of benzaldehyde-N(4)–phenylsemicarbazone have been synthesized and characterized by elemental analyses, molar conductance, electronic and infrared spectral studies. In all the complexes, the semicarbazone is coordinated as neutral bidentate ligand. 1H NMR spectrum of [Zn(HL)2(OAc)2] shows that there is no enolisation of the ligand in the complex. The magnetic susceptibility measurements indicate that Cr(III), Mn(II), Fe(III), Co(II) and Cu(II) complexes are paramagnetic and Ni(II) is diamagnetic. The EPR spectrum of [Mn(HL)2(OAc)2] in DMF solution at 77K shows hyperfine sextet with low intensity forbidden lines lying between each of the two main hyperfine lines. The g values calculated for the [Cu(HL)2SO4] complex in frozen DMF, indicate the presence of unpaired electron in the dx2−y2 orbital. The metal ligand bonding parameters evaluated showed strong in-plane bonding and in-plane bonding. The ligand and complexes were screened for their possible antimicrobial activities.

Synthesis and spectral investigations of vanadium(IV/V) complexes derived from an ONS donor thiosemicarbazone ligand

Four oxovanadium and one dioxovanadium complex with 2-hydroxyacetophenone N(4)- phenylthiosemicarbazone (H2L) which are represented as [VOLphen]·2H2O (1), [VOLbipy] (2), [VOLdmbipy] (3), [VOL]2 (4) and [VO2HL]·CH3OH (5) have been synthesized and characterized by elemental analyses, electronic, infrared and EPR spectral techniques. In all the complexes 1–4 the ligand coordinates through phenolic oxygen, azomethine nitrogen and thiolate sulfur. But in complex [VO2HL]·CH3OH, coordination takes place in thione form instead of thiolate sulfur. All the complexes except [VO2HL]·CH3OH are EPR active due to the presence of an unpaired electron. In frozen DMF at 77 K, all the oxovanadium(IV) complexes show axial anisotropy with two sets of eight line patterns

Lymphoid organ cell culture system from Penaeus monodon (Fabricius) as a platform for white spot syndrome virus and shrimp immune-related gene expression

Shrimp cell lines are yet to be reported and this restricts the prospects of investigating the associated viral pathogens, especially white spot syndrome virus (WSSV). In this context, development of primary cell cultures from lymphoid organs was standardized. Poly-l-lysine-coated culture vessels enhanced growth of lymphoid cells, while the application of vertebrate growth factors did not, except insulin-like growth factor-1 (IGF-1). Susceptibility of the lymphoid cells to WSSV was confirmed by immunofluoresence assay using monoclonal antibody against the 28 kDa envelope protein of WSSV. Expression of viral and immunerelated genes in WSSV-infected lymphoid cultures could be demonstrated by RT-PCR. This emphasizes the utility of lymphoid primary cell culture as a platform for research in virus–cell interaction, virus morphogenesis, up and downregulation of shrimp immune-related genes, and also for the discovery of novel drugs to combat WSSV in shrimp culture

Mn(II) complexes of some acylhydrazones with NNO donor sites: Syntheses, a spectroscopic view on their coordination possibilities and crystal structures

Mn(II) complexes derived from a set of acylhydrazones were synthesised and characterized by elemental analyzes, IR, UV–vis and X-band EPR spectral studies as well as conductivity and magnetic susceptibility measurements. In the reported complexes, the hydrazones exist either in the keto or enolate form, as evidenced by IR spectral data. Crystal structures of two complexes are well established using single crystal X-ray diffraction studies. In both of these complexes two equivalent monoanionic ligands are coordinated in a meridional fashion using cis pyridyl, trans azomethine nitrogen and cis enolate oxygen atoms positioned very nearly perpendicular to each other. EPR spectra in DMF solutions at 77 K show hyperfine sextets and in some of the complexes the low intensity forbidden lines lying between each of the two hyperfine lines are also observed

Syntheses, EPR spectral studies and crystal structures of manganese(II) complexes of neutral N,N donor bidentate Schiff bases and azide/thiocyanate as coligand

Four manganese(II) complexes Mn2(paa)2(N3)4 (1), [Mn(paa)2(NCS)2] 3/2H2O (2), Mn(papea)2(NCS)2 (3), [Mn(dpka)2(NCS)2] 1/2H2O(4) of three neutral N,N donor bidentate Schiff bases were synthesized and physico- chemically characterized by means of partial elemental analyses, electronic, infrared and EPR spectral studies. Compounds 3 and 4 were obtained as single crystals suitable for X-ray diffraction. Compound 4 recrystallized as Mn(dpka)2(NCS)2. Both the compounds crystallized in the monoclinic space groups P21 for 3 and C2/c for 4. Manganese(II) is found to be in a distorted octahedral geometry in both the monomeric complexes with thiocyanate anion as a terminal ligand coordinating through the nitrogen atom. EPR spectra in DMF solutions at 77 K show hyperfine sextets with low intensity forbidden lines lying between each of the two main hyperfine lines and the zero field splitting parameters (D and E) were calculated.

Design and Synthesis of Donor-Acceptor Low Band Gap Copolymers for Photoconductive and Non-linear Optical Applications

The main focus of the present study was to develop ideal low band gap D-A copolymers for photoconducting and non-linear optical applications. This chapter summarizes the overall research work done. Designed copolymers were synthesized via direct arylation or Suzuki coupling reactions. Copolymers were characterized by theoretical and experimental methods. The suitability of these copolymers in photoconducting and optical limiting devices has been investigated.The results suggest that the copolymers investigated in the present study have a good non-linear optical response and are comparable to or even better than the D-A copolymers reported in the literature and hence could be chosen as ideal candidates with potential applications for non-linear optics. The results also show that the structures of the polymers have great impact on NLO properties. Copolymers studied here exhibits good optical limiting property at 532 nm wavelength due to two-photon absorption (TPA) process. The results revealed that the two copolymers, (P(EDOT-BTSe) and P(PH-TZ)) exhibited strong two-photon absorption and superior optical power limiting properties, which are much better than that of others.

Theoretical Design and Synthesis of Donor-Acceptor Conjugated Polymers for Photovoltaic and NLO Applications

Polymers with conjugated π-electron backbone display unusual electronic properties such as low energy optical transition, low ionization potentials, and high electron affinities. The properties that make these materials attractive include a wide range of electrical conductivity, mechanical flexibility and thermal stability. Some of the potential applications of these conjugated polymers are in sensors, solar cells, field effect transistors, field emission and electrochromic displays, supercapacitors and energy storage. With recent advances in the stability of conjugated polymer materials, and improved control of properties, a growing number of applications are currently being explored. Some of the important applications of conducting polymers include: they are used in electrostatic materials, conducting adhesives, shielding against electromagnetic interference (EMI), artificial nerves, aircraft structures, diodes, and transistors.

Prevalencia de enfermedad celiaca en Latinoamérica: revisión sistemática de la literatura y meta-análisis

Introducción: La enfermedad celiaca (EC) es una enfermedad autoinmune (EA) intestinal desencadenada por la ingesta de gluten. Por la falta de información de la presencia de EC en Latinoamérica (LA), nosotros investigamos la prevalencia de la enfermedad en esta región utilizando una revisión sistemática de la literatura y un meta-análisis. Métodos y resultados: Este trabajo fue realizado en dos fases: La primera, fue un estudio de corte transversal de 300 individuos Colombianos. La segunda, fue una revisión sistemática y una meta-regresión siguiendo las guías PRSIMA. Nuestros resultados ponen de manifiesto una falta de anti-transglutaminasa tisular (tTG) e IgA anti-endomisio (EMA) en la población Colombiana. En la revisión sistemática, 72 artículos cumplían con los criterios de selección, la prevalencia estimada de EC en LA fue de 0,46% a 0,64%, mientras que la prevalencia en familiares de primer grado fue de 5,5 a 5,6%, y en los pacientes con diabetes mellitus tipo 1 fue de 4,6% a 8,7% Conclusión: Nuestro estudio muestra que la prevalencia de EC en pacientes sanos de LA es similar a la notificada en la población europea.

Respuesta inflamatoria sistémica en el donante como predictor de infección en el primer mes del trasplante renal

Introducción: El objetivo principal de la selección del donante es disminuir la posibilidad de transmisión de enfermedades infecciosas o neoplásicas en el receptor. De forma cruda se calcula que aproximadamente el 50% de los potenciales donantes son contraindicados, la mayoría por infección. La alta demanda de órganos obliga a revalorar las contraindicaciones que hasta hace poco eran absolutas, el reto es diferenciar el SIRS del donante por Muerte Encefálica con el SIRS por infecciones. Método: Estudio de cohorte retrospectivo; que busca evaluar la respuesta inflamatoria sistémica (SIRS) como predictor de infección en pacientes con trasplante renal en el primer mes pos trasplante. Resultados: El contraste de hipótesis proporciono una significancia bilateral (P= 0,071). La pruebas de hipótesis aceptaron la hipótesis nula (P= 0,071), que no existe asociación entre la presencia de SIRS en el donante con la incidencia de infección en el primer mes del pos trasplante renal. La estimación del riesgo de no reingreso por infección al primer mes pos trasplante renal es de 0.881 veces para los donantes con SIRS (IC 0.757 – 1.025). Conclusión: A pesar de no encontrar significancia estadística: el SIRS en el donante no se asocia con un aumento en la incidencia de infección en el primer mes postrasplante. Para encontrar la significancia se propone un estudio con un tamaño de muestra mayor.

Incidencia y factores asociados a infecciones bacterianas en el primer mes postrasplante hepático en la Fundación Cardioinfantil

Introducción: El trasplante hepático ortotópico es la colocación de un nuevo hígado en la misma ubicación del explantado. El objetivo es prolongar la duración y la calidad de vida en pacientes con enfermedades hepáticas terminales. Sin embargo, las infecciones bacterianas son una complicación en los pacientes receptores del trasplante, comprometiendo el éxito del procedimiento. El objetivo fue determinar los factores asociados a infecciones bacterianas en el primer mes tras realizada la intervención y describir las características demográficas de esa población. De 332 trasplantes realizados, que 262 cumplieron criterios para el análisis. Métodos: Se realizó un estudio observacional analítico de casos y controles anidado en una cohorte, en mayores de 18 años, receptores de trasplante hepático primario, de la FCI-IC de 2005 a 2014; excluyendo trasplante combinado hígado riñón, retrasplantes o fallecidos por causa diferente a la infecciosa durante el primer mes. Resultados: Se encontró que la ventilación mecánica por más de 1 día, el catéter venoso central mayor de 3 días son los principales factores de riesgo para infecciones bacterianas. La albúmina mayor de 2,6gr/dl se asoció a menor infección. Los agentes etiológicos predominantes fueron gérmenes gram negativos como E. coli, K. pneumonia y E. cloacae. Mientras que bacteremia, infección urinaria y peritonitis fueron las infecciones más frecuentes. La incidencia de infección bacteriana en esta población fue 24%. Discusión: Se recomienda por tanto extubación antes de 24 horas, uso de catéter central menor de 3 días y limitar el uso del catéter vesical.

Estimation of electronic coupling in π -stacked donor-bridge-acceptor systems: correction of the two-state model

Comparison of donor-acceptor electronic couplings calculated within two-state and three-state models suggests that the two-state treatment can provide unreliable estimates of Vda because of neglecting the multistate effects. We show that in most cases accurate values of the electronic coupling in a π stack, where donor and acceptor are separated by a bridging unit, can be obtained as Ṽ da = (E2 - E1) μ12 Rda + (2 E3 - E1 - E2) 2 μ13 μ23 Rda2, where E1, E2, and E3 are adiabatic energies of the ground, charge-transfer, and bridge states, respectively, μij is the transition dipole moments between the states i and j, and Rda is the distance between the planes of donor and acceptor. In this expression based on the generalized Mulliken-Hush approach, the first term corresponds to the coupling derived within a two-state model, whereas the second term is the superexchange correction accounting for the bridge effect. The formula is extended to bridges consisting of several subunits. The influence of the donor-acceptor energy mismatch on the excess charge distribution, adiabatic dipole and transition moments, and electronic couplings is examined. A diagnostic is developed to determine whether the two-state approach can be applied. Based on numerical results, we showed that the superexchange correction considerably improves estimates of the donor-acceptor coupling derived within a two-state approach. In most cases when the two-state scheme fails, the formula gives reliable results which are in good agreement (within 5%) with the data of the three-state generalized Mulliken-Hush model

Electronic and vibrational contributions to first hyperpolarizability of donor-acceptor-substituted azobenzene

In this study we report on the electronic and vibrational (hyper)polarizabilities of donor–acceptorsubstituted azobenzene. It is observed that both electronic and vibrational contributions to the electric dipole first hyperpolarizability of investigated photoactive molecule substantially depend on the conformation. The contributions to the nuclear relaxation first hyperpolarizability are found to be quite important in the case of two considered isomers (cis and trans). Although the double-harmonic term is found to be the largest in terms of magnitude, it is shown that the total value of the nuclear relaxation contribution to vibrational first hyperpolarizability is a result of subtle interplay of higher-order contributions. As a part of the study, we also assess the performance of long-range-corrected density functional theory in determining vibrational contributions to electric dipole (hyper)polarizabilities. In most cases, the applied long-range-corrected exchange correlation potentials amend the drawbacks of their conventional counterparts