Exploting benzene´s unknown Mr Hyde character to develop new photochemistry

This is a a seminar dealing with the new discoveries on benzene reactivity based on its Mr Hyde character in order to develop new photochemistry.This is a a seminar dealing with the new discoveries on benzene reactivity based on its Mr Hyde character in order to develop new photochemistry.Vicerrectorado de Investigación de la UMA. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Solvent Effects in Supramolecular Systems

Today it is well-established that solvents demonstrate an important role in chemistry. Solvents are able to affect the reactivity, as well as the electronic, optical, and generally physicochemical properties of compounds in solution. Taking this into account, in this chapter we analyze the importance of solvent polarity in phenomena closely related to supramolecular systems as well as the aptitude of various supramolecules to interact with solvent molecules and thus to give rise to chromic effects such as solvatochromism. Main focus is placed on mechanically interlocked molecules, e.g., rotaxanes, catenanes, etc., exhibiting solvent-controlled shuttling movements, switching, and/or solvatochromism. The effect of solvents in various supramolecular architectures is a further focus of this chapter

Photoconductive Interlocked Molecules and Macromolecules

Organic compounds and materials with photoconductive properties have been studied for many years because of their importance in many technological applications such as dye-sensitized solar cells, photodiodes, photoresistors, electronics, biomolecular sensing, etc. For multiple purposes, such molecules require intense protection from various factors which can decrease their durability and cause fatigue. Interlocked molecules and macromolecules involving photoconductive organic components and various types of macrocycles, such as cyclodextrins, cyclophanes, or macrocyclic ethers, are promising candidates for new photoconductivity-related applications. In this chapter, a review in this emerging research area in materials science and technology is provided. Focus is placed on photoconductive (poly)rotaxanes and (poly)catenanes. Various types of such materials and compounds are reviewed, and recent examples are provided. The relation between their structure and photoconductive behavior is discussed

Probing Solvation Effects in Binary Solvent Mixtures with the Use of Solvatochromic Dyes

In this work three molecules exhibiting dual sensing solvatochromic behaviors are examined in the context of solvation in binary solvent mixtures (BSMs). The compounds studied involve two functional groups with high responsiveness to solvent polarity namely pentacyanoferrate(II) (PC) and azo groups. Two of these compounds are [2]rotaxanes involving alpha- or beta- cyclodextrin (CyD) and the third is their CyD-free precursor. The dual solvatochromic behavior of these compounds is investigated in water/ethlylene glycol (EG) mixtures and their dual solvatochromic responses are assessed in terms of the intensity of solvatochromism and the extent of preferential solvation. To achieve this the linear solvation model by Kamlet, Abboud and Taft [J. Organomet. Chem. 1983, 48, 2877–2887] and the two-phase model of solvation by Bagchi and coworkers [J. Phys. Chem. 1991, 95, 3311–3314] are employed. The influence of the presence or lack of CyD (alpha- or beta-) on these dual solvatochromic sensors is analyzed

Fluorescence Imaging Enhanced by Members of the Graphene Family: A Review

Graphene is a two-dimensional allotrope of carbon with a range of highly attractive physicochemical properties suitable for a wide variety of applications. In the context of fluorescence imaging graphene and its derivatives have recently started to gain more attention since they could assist in the enhancement of imaging of cells, tissue, or other biologically relevant samples such as cell organoids for example mitochondria as well as in the imaging of cancer cells, tumors, and various pathogens. This chapter attempts to cover the most relevant, recent advances in this growing research field. Some basic information on the physical and (photo)chemical properties of important members of the graphene family is provided. Additionally, novel approaches involving graphene-based materials (GBMs) in cellular and tissue imaging systems are reviewed. Important examples of contemporary applications of GBMs in cancer detection using fluorescence imaging are also presented. The specific role of graphene (or other GBMs) in each case is explained and analyzed. Finally, future perspectives and novel applications of fluorescent imaging techniques involving GBMs are discussed

Mono- and Di-Quaternized 4,4 '-Bipyridine Derivatives as Key Building Blocks for Medium- and Environment-Responsive Compounds and Materials

Mono- and di-quaternized 4,4'-bipyridine derivatives constitute a family of heterocyclic compounds, which in recent years have been employed in numerous applications. These applications correspond to various disciplines of research and technology. In their majority, two key features of these 4,4'-bipyridine-based derivatives are exploited: their redox activity and their electrochromic aptitude. Contemporary materials and compounds encompassing these skeletons as building blocks are often characterized as multifunctional, as their presence often gives rise to interesting phenomena, e.g., various types of chromism. This research trend is acknowledged, and, in this review article, recent examples of multifunctional chromic materials/compounds of this class are presented. Emphasis is placed on solvent-/medium- and environment-responsive 4,4'-bipyridine derivatives. Two important classes of 4,4'-bipyridine-based products with solvatochromic and/or environment-responsive character are reviewed: viologens (i.e., N,N'-disubstituted derivatives) and monoquats (i.e., monosubstituted 4,4'-bipyridine derivatives). The multifunctional nature of these derivatives is analyzed and structure-property relations are discussed in connection to the role of these derivatives in various novel applications

Preferential Solvation of a Highly Medium Responsive Pentacyanoferrate(II) Complex in Binary Solvent Mixtures: Understanding the Role of Dielectric Enrichment and the Specificity of Solute–Solvent Interactions

In this work, the preferential solvation of an intensely solvatochromic ferrocyanide­(II) dye involving a 4,4′-bipyridine-based ligand was examined in various binary solvent mixtures. Its solvatochromic behavior was rationalized in terms of specific and nonspecific solute–solvent interactions. An exceptional case of solvatochromic inversion was observed when going from alcohol/water to amide/water mixtures. These effects were quantified using Onsager’s solvent polarity function. Furthermore, the sensitivity of the solvatochromism of the dye was determined using various solvatochromic parameters such as <i>π*</i> expressing the dipolarity/polarizability of solvents and α expressing the hydrogen-bond-donor acidity of solvents. This analysis was useful for the rationalization of the selective solvation phenomena occurring in the three types of alcohol/water and amide/water mixtures studied. Furthermore, two preferential solvation models were employed for the interpretation of the experimental spectral results in binary solvent mixtures, namely, the model of Suppan on dielectric enrichment [<i>J. Chem. Soc. Faraday Trans. 1</i> <b>1987</b>, 83, 495–509] and the model of Bosch, Rosés, and co-workers [<i>J. Chem. Soc., Perkin Trans. 2</i>, <b>1995</b>, 8, 1607–1615]. The first model successfully predicted the charge transfer energies of the dye in formamide/water and <i>N</i>-methylformamide/water mixtures, but in the case of MeOH/water mixtures, the prediction was less accurate because of the significant contribution of specific solute–solvent interactions in that case. The second model gave more insights for both specific solute–solvent as well as solvent–solvent interactions in the cybotactic region. The role of dielectric enrichment and specific interactions was discussed based on the findings

Click Chemistry Enabling Covalent and Non-Covalent Modifications of Graphene with (Poly)saccharides

Graphene is a material with outstanding properties and numerous potential applications in a wide range of research and technology areas, spanning from electronics, energy materials, sensors, and actuators to life-science and many more. However, the insolubility and poor dispersibility of graphene are two major problems hampering its use in certain applications. Tethering mono-, di-, or even poly-saccharides on graphene through click-chemistry is gaining more and more attention as a key modification approach leading to new graphene-based materials (GBM) with improved hydrophilicity and substantial dispersibility in polar solvents, e.g., water. The attachment of (poly)saccharides on graphene further renders the final GBMs biocompatible and could open new routes to novel biomedical and environmental applications. In this review, recent modifications of graphene and other carbon rich materials (CRMs) through click chemistry are reviewed