Synthesis, characterization and antibacterial studies of metal complexes of substituted thiourea

Eighteen complexes Co(II), Cu(II), Zn(II), and Fe(III) with phenylthiourea, diethylthiourea, disopropylthiourea and dimethylthiourea were synthesized and characterized by elemental analysis, UV-Vis, FTIR, conductivity measurements. The complexes were formulated as either four coordinate for the metal(II) or six coordinate for Fe(III). The proposed formulations are consistent with the spectroscopic data for the complexes. The single crystal X-ray structure of the Zn(II) complex of phenylthiourea, Co(II) complex of diethylthiourea and Zn(II) complex of diisopropylthiourea are also reported. The X-ray crystal structures for these complexes revealed distorted tetrahedral geometry around the metal ions showed that the metal ions are coordinated to two molecules of the substituted thiourea through the sulphur atom and two either acetates or chlorides ions complete the four-coordinate geometry. The in vitro antibacterial activity of the complexes was studied against six bacterial strains using disc diffusion and broth micro-dilution methods. The complexes showed selective antibacterial activity.Thesis (MSc) -- Faculty of Science and Agriculture, 201

MULTI-FUNCTIONAL CARBON DOTS: A SYSTEMATIC OVERVIEW

Carbon dots (CDs) have emerged as a potential material in the multifarious fields of biomedical applications due to their numerous advantageous properties including tunable fluorescence, water solubility, biocompatibility, low toxicity, small size and ease of modification, inexpensive scale-up production, and versatile conjugation with other targeted nanoparticles. Thus, CDs became a preferable choice in various biomedical applications such as nanocarriers for drugs, therapeutic genes, photo sensitizers, unique electronic, fluorescent, photo luminescent, chemiluminescent, and electro chemiluminescent, drug/gene delivery and optoelectronics properties are what gives them potential in sensing and antibacterial molecules. Further, their potentials have also been verified in multifunctional diagnostic platforms, cellular and bacterial bio-imaging, development of nanomedicine, etc. This present review provides a concise insight into the progress and evolution in the field of carbon dots research with respect to synthesis methods and materials available in bio-imaging, theranostic, cancer, gene therapy, diagnostics, etc. Further, our discussion is extended to explore the role of CDs in nanomedicine and nano theranostic, biotherapy which is the future of biomedicine and also serves to discuss the various properties of carbon dots which allow chemotherapy and gene therapy to be safer and more target-specific, resulting in the reduction of side effects experienced by patients and also the overall increase in patient compliance and quality of life and representative studies on their activities against bacteria, fungi, and viruses reviewed and discussed. This study will thus help biomedical researchers in percuss the potential of CDs to overcome various existing technological challenges

Asymmetric Ligands Derived from Carbohydrates

This thesis describes the incorporation of carbohydrate groups in thiourea, 1, or iminophosphorane, 2, ligands. Several carbohydrate acyl thioureas, 3, were synthesised from the reaction of protected and unprotected D‐glucosamine with acyl isothiocyanates, RCONCS. Internal hydrogen‐bonding forms a planar six‐membered ring, which locks the thiourea into an Z,E,Z‐anti conformation as shown by 1H NMR spectroscopy and confirmed by X‐ray structure determination of two examples. As neutral ligands to Rh(III), Rh(I), Ru(II), Pd(II), Pt(II) and Au(I) they bond through the sulfur atom with retention of the six‐membered ring and the Z,E,Z‐anti conformation. This was confirmed by two X‐ray structure determinations on Rh(III) and Pd(II) examples which also showed the new hydrogen‐bond formed by HN2 to a halide on the metal. Deprotonation of the ligands 3 with NaOAc gave anionic species which formed bidentate chelating complexes with metals. When attached to Rh(III), Ru(II) or with two thiourea bonding to Pd(II) it forms a four‐membered ring through the S and N2 atoms which retains the hydrogen‐bond. If Rh(I) or (C,Ndimethylbenzylamine‐ Pd) is used a six‐membered ring is formed through the S and O atoms which disrupts the hydrogen‐bond. This disruption of the hydrogenbond is apparent from the chemical shift of HN1. For examples where coordination led to a chiral metal complex (e.g. for Cp*RhCl(N,S‐thiourea)) NMR measurements showed that the natural chirality of the ligand did not provide any selectivity with equal proportions of the two diastereoisomers formed. Iminophosphoranes were produced by the reaction of protected sugar azides with phosphines via the Staudinger reaction. Cyclometalated complexes, 4, could not be formed directly which an X‐ray structure determination suggested was because of steric crowding of the nitrogen. An indirect transmetalation route was developed where the sugar azides were reacted with the mercurated diphosphine, Hg(2‐C₆H₄PPh₂)₂, and the resulting iminophosphoranes transmetalated with [NMe₄][AuCl₄] to produce cyclometalated Au(III) dichloride complexes. Two X‐ray structure determinations showed that the five‐membered metalocyclic ring was in an envelope conformation. The chlorides were labile and able to be displaced by PPh3 and thiosalicylic acid. A series of N‐sugar and N‐phenyl iminophosphorane Au(III) complexes were shown to catalyse the addition of 2‐methyl furan to methyl vinyl ketone

Electron paramagnetic resonance applications: from drug discovery to marine biology studies

El leitmotiv de la tesis es el uso de la técnica EPR, que implica el estudio de la dinámica de interacción de sistemas de interés con la ayuda de especies paramagnéticas apropiadas. El trabajo realizado en los tres años del doctorado se centró en el estudio químico-físico de moléculas de uso biomédico, más un trabajo extra sobre la interacción químico-física entre algunas formas de fitoplancton y microplásticos. La tesis se desarrolla en tres líneas de investigación: 1. El estudio de los glicodendrímeros para el tratamiento de la enfermedad de Wilson ocupó la mayor parte del primer año. Una nueva familia de glicodendrímeros, modificados con grupos DOTA, fue sintetizada el centro de investigación Leibniz-Intitute de Dresden, y analizada para evaluar su habilidad de quelar átomos de Cu(II). En particular, se puso bajo la lupa la interacción químico-física entre estas moléculas y los modelos de membrana, que confirmó su posible aplicación en campo biomédico. Este estudio condujo a la redacción de un artículo publicado en Langmuir. 2. Durante los tres años, se trabajó en la síntesis, caracterización y aplicación de metalodendrímeros para el tratamiento de diversas formas de neoplasia. La combinación de esta clase de polímeros e iones metálicos permite un control fino de los mecanismos anticancerígenos, que pueden moldearse según el sistema en estudio. Nuevas familias de metalodendrímeros de cobre y rutenio fueron sintetizadas en Alcalá y estudiadas bajo un punto de vista químico-físico en la universidad de Urbino. En este contexto, se han publicado 3 artículos y una reseña, además de un último artículo en proceso de peer review. 3. Un proyecto nacido y concluido en pocos meses con la publicación de un artículo en Chemosphere, se refiere a la demostración de la interacción física de algunos tipos de fitoplancton y microplásticos presentes en el Mediterráneo, para explicar un fenómeno particular de bio-contaminación que ha surgido en los últimos años. Dicha interacción fue estudiada en Urbino por medio de técnicas químico-físicas

Physicochemical studies of some compounds

Not availabl

Calixarene Complexes: Synthesis, Properties and Applications

A growing interest has been devoted to the development of host systems for ionic and neutral species based on calixarenes. These cyclic oligomers show important host–guest properties, which has led to numerous applications in a broad range of fields, including organocatalysis, sensing, extraction and separation, and, more recently, biomedical applications. The relative ease of the functionalization of their upper and lower rims and the presence of a pre-organized cavity that is available in different sizes and conformations make calixarenes attractive building blocks for the construction of supramolecular assemblies. This book presents the most recent developments on the host–guest properties of calixarenes, as well as the new synthetic methods and applications

Synthesis and Characterization of Nature Inspired Fluorophores

Oxyluciferin is the product of bioluminescence reaction of firefly luciferin. It has a highly conjugated structure and is non-toxici to animal cells. The thesis concerns the investigation of transforming the features of oxyluciferin into a bio-friendly fluorophore. The background and introduction chapters include how the fluorescence phenomenon has been discovered and a mechanistic explanation. It also covers several typical fluorophores and their applications. The second chapter starts from the design of keto and iminium derivatives of oxyluciferin with different electron-donating substituents. Then moves to their chemical synthesis includes direct condensation reaction between the corresponding ketone and dialkylamine. The third chapter covers the design of pyridine and pyridinium derivatives of oxyluciferin, the synthesis of which includes cyclisation methods of constructing thiazole and thiazolopyridine rings. Around 20 novel analogues have been successfully synthesized. The fourth part gives a brief description of optical properties of all the fluorophores prepared, includes some aggregation induced emission (AIE) fluorophores. The fluorescence of different analogues have nearly covered the entire visible light region. The bioconjugation reaction of the most promising fluorophore with an antibody illustrates the potential of its biological application. The final chapter contains detailed experimental procedures and charcacterisation data. The thesis is fully referenced to the primary literature

The versatile biomedical applications of bismuth-based nanoparticles and composites : therapeutic, diagnostic, biosensing, and regenerative properties

Studies of nanosized forms of bismuth (Bi)-containing materials have recently expanded from optical, chemical, electronic, and engineering fields towards biomedicine, as a result of their safety, cost-effective fabrication processes, large surface area, high stability, and high versatility in terms of shape, size, and porosity. Bi, as a nontoxic and inexpensive diamagnetic heavy metal, has been used for the fabrication of various nanoparticles (NPs) with unique structural, physicochemical, and compositional features to combine various properties, such as a favourably high X-ray attenuation coefficient and near-infrared (NIR) absorbance, excellent light-to-heat conversion efficiency, and a long circulation half-life. These features have rendered bismuth-containing nanoparticles (BiNPs) with desirable performance for combined cancer therapy, photothermal and radiation therapy (RT), multimodal imaging, theranostics, drug delivery, biosensing, and tissue engineering. Bismuth oxyhalides (BiOx, where X is Cl, Br or I) and bismuth chalcogenides, including bismuth oxide, bismuth sulfide, bismuth selenide, and bismuth telluride, have been heavily investigated for therapeutic purposes. The pharmacokinetics of these BiNPs can be easily improved via the facile modification of their surfaces with biocompatible polymers and proteins, resulting in enhanced colloidal stability, extended blood circulation, and reduced toxicity. Desirable antibacterial effects, bone regeneration potential, and tumor growth suppression under NIR laser radiation are the main biomedical research areas involving BiNPs that have opened up a new paradigm for their future clinical translation. This review emphasizes the synthesis and state-of-the-art progress related to the biomedical applications of BiNPs with different structures, sizes, and compositions. Furthermore, a comprehensive discussion focusing on challenges and future opportunities is presented.Peer reviewe

Sustainable Approaches for the Synthesis of Nitrogen and Oxygen Functionalized Small Organic Molecules.

Two important categories of O-functionalized compounds are O-heterocycles and polyphenols. All these two categories are widespread in nature and present as scaffold in many natural compounds. Well-known examples are sugar core of DNA and RNA, Quercitin, Curcumin, Vitamins (especially E and C), Taxol, Dynemicin, and many others; and their biological applications are well-known too (anti-inflammatory, anti- oxidant, antiviral, anticancer and others). The synthesis of O-functionalized compounds has been always an important and crucial research field of organic synthesis and nowadays many methods are reported in literature.[20 - 25] This first chapter is focused on two different projects related together by the O- functionalization of final target products and by the very important biological, antiviral, therapeutical applications that they found or they could find. The aim of first section is to synthesize LNA-Adenosine derivative by linear strategy. The LNA (Locked Nucleic Acid) are very important Nucleic Acid analogues, synthesized for the first time by Iminashi et al. [26] and Wengel et al.[27] respectively in 1997 and 1998, in an independently way. These analogues are very important due to the antisense, antigene, antiviral, and many others bio-applications, overcoming some problems related to employment of not-modified nucleic acids. The topic of the second chapter is the synthesis of a new phenolic compound with potential antiviral activity against Sars-CoV-2. Our purpose is to obtain this new polyphenol through the combination of two intermediates, an alkyne and an aldehyde, obtained from two commercial, cheap and easy available starting material. Natural and synthetic heterocycles has greatly attracted the interest of scientits because of their widely applications in many fields of science: biological, pharmaceutical, synthetical and industrial applications (plastic, solvents, cosmetics, vulcanization accelerators, etc.)[175] Among them, N-heterocycles have always constituted an important synthetic target due to the pharmaceutical and biological superior properties than non-nitrogen containing cycles[175b] and for their wide distribution in many natural bioactive compounds (such as alkaloids).[176] From a statistical analyses it emerges that 59% of FDA-approved small molecule drugs contain at least one of N-heterocycles moieties in which the six- and five-membered are the size-cycles more diffused, although three-, four-, bicyclic-, macrocyclic N-heterocycle scaffolds are present.[177] Moreover, this last class of compounds have shown useful, not only in medicinal fields, but also in metallurgical applications thanks by their ability to chelate first-row transition metals like Mn(II), Zn(II), Fe(II), Cu(II) and for other industrial applications.[178] Nowadays many scientist are focusing on the development of new sustainable synthetic approaches for this class of compounds[175a] given their potential applicability in many science and everyday life aspects. New approaches consist in employment of UV-light (the most sustainable reactions induces, largely applied in organic synthesis); [179] employment of less toxic, environmentally benign and less expensive Lewis Acid catalysts like Zn, Fe, Cu, Ni cores (minimization of waste, time consuming, improved selectivity, often they allow to build complicated structures under mild conditions);[175a], [180] performing the reaction under microwave irradiations;[181] through multicomponent reactions (which implicate time saving, avoid the separation and purification of intermediates, atom- efficent reactions, type reactions used also for the synthesis of pharmaceuticals, drugs and compounds by stereoselective routes);[182] employment of less toxic solvents like ionic liquid;[183] just to cite few examples. This chapter is divided in three sections in which three different N-heterocycle scaffolds are synthesized by new sustainable approaches. The first section is focused on the synthesis of an aza-macrocycle with the purpose to overcome some problems related to the synthesis and enhanced some aspects making them more suitable for green aspects that rule the scientific world today. The aim of second section is the synthesis of a six-membered N-heterocycles (1,2- dihydropyridines) through polycondensation of acyclic precursor using a not expensive and low-toxic Lewis acid like CeCl3 .7H2O, emphasizing kinetic, thermodynamic aspects of condensation process. The last section is divided in two more parts in which: the first one focuses on the synthesis of tetrahydro-β-carboline (very important bioactive compound) using not harmful Brønsted acids like graphene oxide and Amberlyst-15® through the Pictect- Spengler reaction; the second part, instead, reports the first results about the development of a new multi-component Pictect-Spengler reaction promoted by Ce(III)-Lewis Acid for the synthesis of N-substituted tetrahydro-β-carboline

Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018

The First Conference on materials science and engineering, including physics, physical chemistry, condensed matter chemistry, and technology in general, was held in September 1995, in Herceg Novi. An initiative to establish Yugoslav Materials Research Society was born at the conference and, similar to other MR societies in the world, the programme was made and objectives determined. The Yugoslav Materials Research Society (Yu-MRS), a nongovernment and non-profit scientific association, was founded in 1997 to promote multidisciplinary goal-oriented research in materials science and engineering. The main task and objective of the Society has been to encourage creativity in materials research and engineering to reach a harmonic coordination between achievements in this field in our country and analogous activities in the world with an aim to include our country into global international projects. Until 2003, Conferences were held every second year and then they grew into Annual Conferences that were traditionally held in Herceg Novi in September of every year. In 2007 Yu-MRS formed two new MRS: MRS-Serbia (official successor of Yu-MRS) and MRS-Montenegro (in founding). In 2008, MRS – Serbia became a member of FEMS (Federation of European Materials Societies)