Controlling the aggregation of planar photosensitizers and electroluminescent materials

Conferencia Científica del Dpto. Química OrgánicaAggregation of planar chromophores greatly affects their photophysical performance. It is possible to avoid the aggregation of phthalocyaninates by axially binding them to the surface of aluminosilicates. We have recently designed a multifunctional zeolite L-based hybrid material able to target, label and photoinactivate pathogenic and antibiotic resistant bacteria.[1,2] The outer surface was functionalized with a Si(IV) phthalocyanine derivative that forms toxic singlet oxygen upon red light irradiation, and with amino groups for targeting the living microorganisms. Currently, we aim to extend these concepts to targeted, fully soluble and biodegradable platforms, a prerequisite for biomedical applications.[3,4] We have recently developed a straightforward one-pot synthesis of neutral, soluble Pt(II) coordination compounds bearing dianionic tridentate ligands. The complexes reached up to 87% photoluminescence quantum yield (PLQY) in thin films, with concentration independent colour and efficiency.[5] Consequently, we demonstrated their suitability as phosphorescent dopants in organic light-emitting diodes (OLEDs). Furthermore, the judicious choice of bulky peripheral substituents allowed us to completely prevent aggregation and to enhance color purity, a critical aspect when designing triplet emitters for electroluminescent devices.[6] On the other hand, we were able to deliberately induce self-assembly into bright nanofibers, which can interlock to yield highly emissive organo- and hydrogels (90% PLQY), thus constituting a versatile building block for luminescent architectures. The unique properties of the filaments arise from the metal-metal to ligand charge-transfer states of the aggregated species, which display strong Pt-Pt interactions. It is therefore possible to trace the self-assembly process with high sensitivity by monitoring the turn-on of the emission upon aggregation.[5] Currently, we investigate the electronic coupling between Pt(II) d-orbitals and electrodes at single molecule level, employing scanning tunnel microscopy and scanning tunnel spectroscopy.[7] Our results elegantly show how a careful, rational design allow us to fully control the aggregation of planar chromophores, and, consequently, to tune their photophysical and photochemical properties.Vicerrectorado de Investigación y Transferencia. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Exploiting metallophilicity for the assembly of inorganic nanocrystals and conjugated organic molecules

The accurate engineering of interfaces between inorganic nanocrystals and semiconducting organic molecules is currently viewed as key for further developments in critical fields such as photovoltaics and photocatalysis. In this work, a new and unconventional source of interface interaction based on metal–metal bonds is presented. With this aim, an AuI organometallic gelator was exploited for the formation of hydrogel-like nanocomposites containing inorganic nanoparticles and conjugated organic molecules. Noteworthy, the establishment of metallophilic interactions at the interface between the two moieties greatly enhances interparticle coupling in the composites. Thus, we believe that this new hybrid system might represent a promising alternative in several fields, such as in the fabrication of improved light-harvesting devices.Peer ReviewedPostprint (author's final draft

The manufacture and products thereof of photo-sensitizing nanomaterials and their use in photodynamic treatments

A method for the manufacture of a photosensitizing nanoma terial (40) and the products thereof are disclosed. The method for the treatment of a biological target (50) is disclosed. The photosensitizing nanomaterial (40) comprises a metal com plex tetrapyrrole derivative (10). The metal complex tetrapy rrole derivative (10) is attached by an axial covalent bond (60) to the surface (25) of a solid nanomaterial (20). The solid nanomaterial (20) has at least one dimension in the nanometer and/ or the micrometer range

Pt(II)-dendrimers as bio-imaging marker for bacteria in two-photon excitation microscopy

The use of luminescent markers based on metal complexes in two-photon excitation microscopy techniques are of great interest in the field of bioimaging. However, despite the excellent luminescent properties of Pt(II) complexes, their application in this field is still limited, due to their poor solubility and quenching problems in aqueous media [1]. The insertion of a Pt(II) complex into a dendritic structure, gives as a result an unique luminescent marker soluble in biological media. Dendrimers provides excellent properties to the metal complex such as solubility in aqueous media, protection against quenching processes and binding to bacterial surfaces. The new probe can be used as bacteria cells marker in luminescent microscopy, operating under one or two-photon excitation (OPE/TPE) conditions, as well as in electron microscopy, thus providing a powerful tool in the field of bioimaging.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Influence of Metal, Ligand and Solvent on Supramolecular Polymerizations with Transition-Metal Compounds: A Theoretical Study

The nature of intermolecular interactions governing supramolecular polymerizations is very important to control their cooperativity. In order to address this problem, supramolecular columns made of Pt(II) and Pd(II) complexes of oligo(phenyleneethynylene)-based pyridine (OPE) and tetrazolyl-pyridine ligands (TEP) were investigated through the dispersion-corrected PM6 method. Aromatic, CH-π, M-Cl and metallophilic interactions helped stabilize the supramolecules studied, and their geometries and associated cooperativities were in excellent agreement with experimental data. The OPE ligand and/or the presence of Pt(II) have led to stronger metallophilic interactions and also to cooperative supramolecular polymerizations, which clearly suggests that metallophilic interactions are a key factor to control cooperativity. The results indicate that sequential monomer addition is in general less spontaneous than the combination of two larger pre-formed stacks. The present theoretical investigations contribute to the further understanding of the relation between the thermodynamics of supramolecular polymerizations and the nature of different synthons

SelOpt: Selection of Options based on the Balance and Ranking Method

A new multiple criteria decision-making (MCDM) method, called the Balancing and RankingMethod, is presented. The method overcomes some of the deficiencies of other MCDM methods, such assubjective evaluation of criteria weights, scoring of options, statistical estimation of weights andspecification of the utility function for criteria. The new method uses a three-step procedure to derive anoverall complete final order of options. First, an outranking matrix is derived, which indicates the frequencywith which one option is superior to all other options based on each criterion. Second, the outranking matrixis triangularized to obtain an implicit pre-ordering or provisional order of options. Third, the provisionalorder of options is subjected to various screening and balancing operations that require sequential applicationof a balancing principle to the so-called advantages-disadvantages table that combines the criteria with thepair-wise comparisons of options

On the use of porous nanomaterials to photoinactivate E. coli with natural sunlight irradiation

.An organic-inorganic hybrid material based on nanocrystals of zeolite L functionalized with silicon phthalocyanine can develop interesting properties when activated by natural sunlight. Cell viability tests show that this nanomaterial is able to photoinactivate mouse cells and Escherichia coli (. E. coli) bacteria, and is also very efficient against the self-defense mechanisms of E. coli during the first minutes of solar irradiation. The results suggest that Gram-negative E. coli become more resistant to singlet oxygen-based disinfection treatments at higher temperatures. The present work contributes to the development of new functional materials for a range of important sunlight-based applications. © 2015 Elsevier Lt

New nephridiophagid genera (Fungi, Chytridiomycota) in a mallow beetle and an earwig

Nephridiophagids are unicellular fungi (Chytridiomycota) that infect the Malpighian tubules of insects. Most species have been found in cockroach hosts and belong to the genus Nephridiophaga. Three additional genera have been described from beetles and an earwig. Here, we characterise morphologically and molecular phylogenetically the nephridiophagids of the European earwig Forficula auricularia and the mallow beetle Podagrica malvae. Their morphology and life cycle stages resemble those of other nephridiophagids, but their rRNA gene sequences support the existence of two additional genera. Whereas the earwig nephridiophagid (Nephridiochytrium forficulae gen. nov. et sp. nov.) forms a sister lineage of the Nephridiophaga cluster, the mallow beetle nephridiophagid (Malpighivinco podagricae gen. nov. et sp. nov.) represents the earliest divergent lineage within the nephridiophagids, being sister to all other species. Our results corroborate the hypothesis that different insect groups harbour distinct nephridiophagid lineages