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Terpenes are natural molecules of valuable interest for different industrial applications. Cytochromes P450 enzymes can functionalize terpenoids to form high value oxidized derivatives in a green and sustainable manner, representing a valid alternative to chemical catalysis. In this work, an enhanced and specific epoxidation activity of cytochrome P450 BM3 mutants was found for the terpenes geraniol and linalool. This is the first report showing the epoxidation of linalool by P450 BM3 and its mutant A2 (Asp251Gly/Gln307His) with the formation of valuable oxide derivatives, highlighting the relevance of this enzymes for industrial applications.

The combination of TiO2 and chitosan is known to allow the achievement of implantable devices which combines the mechanical properties of TiO2, with the presence of chitosan, which ensures antibacterial properties combined with an in-situ drug-delivery of biomolecules physisorbed and/or covalently linked to chitosan. In this study, 5-aminofluorescein (5-AF), a derivative of fluorescein containing a primary amino group, has been used as model molecule to simulate a drug. This dye is characterized by low cost and low toxicity, and due to its high molar absorptivity it can easily be detected by means of absorption and emission spectroscopies. The combination of 5-AF and maleic anhydride (MA) with TiO2-chitosan materials has generated a range of novel hybrid materials tailored to applications in localized stimuli-responsive drug delivery systems. Maleic anhydride has been used as pH sensitive spacer for the covalent functionalization of the TiO2-chitosan hybrid with MA as linker molecule. This functionalization allowed to obtain a pH-sensitive hybrid material. The efficiency of the functionalization has been verified by means of different physico-chemical characterization techniques. The behaviour of the functionalized materials is related to different parameters, among which the ratio between physisorbed/coordinated and chemisorbed 5-AF and the matrix degradation. Moreover, delivery tests in simulated body solutions at different pH have been performed showing a pH-sensitive drug delivery behaviour and indicating that the release of 5-AF is favoured at basic pH.

Imidazo[1,5

The commercialization of perovskite solar cells (PSCs) has seen an important limitation in the instability that afflicts the hole-transporting layer (HTL), namely, spiro-OMeTAD, used in high-effici...

Three-dimensional printing (3DP) is considered among the key-technologies for the next industrial revolution, with considerable effects on production processes, economy, and society. In this contex...

We report on the synthesis of a novel class of functionalized thia[6]helicenes and a thia[5]helicene, containing a benzothiophene unit and a second heteroatom embedded in the helix (i.e., nitrogen and oxygen) or a pyrene or a spirobifluorene moiety. These systems are obtained through straightforward and general procedures that involve: (i) palladium-catalyzed annulation of iodo-atropoisomers with internal alkynes and (ii) Suzuki coupling of iodo-atropoisomers with phenyl boronic acid followed by a Mallory-type reaction. Both experimental and theoretical studies on the configurational stability of some selected thia[6]helicenes confirmed their stability toward racemization at room temperature, while the pyrene-based thia[5]helicene was found to be unstable. Moreover, the configuration assignment for one representative thiahelicene was established through the comparison between experimental and theoretical circular dichroism (CD) spectra. A systematic study of the photophysical properties of both thiahelicenes and the corresponding atropoisomers has been carried out to provide a complete overview on the new molecules proposed in this work. The obtained data showed regular trends in all the thiahelicene series with spectroscopic traits in line with those previously observed for similar heterohelicenes.

In the last few years, imidazo [1,5-a] pyridine derivatives have attracted growing attention due to their unique optical behaviours. Herein, a series of trifluoromethylated substituted imidazo [1,5-a] pyridine derivatives were synthesized and their optical properties investigated. Depending on the position of the trifluoromethylated substituents on the imidazo [1,5-a] pyridine nucleus, we were able to tune the quantum yields (Φ) both in acetonitrile solution (from 13% to 39%) and in the polymeric matrix (10%–58%) with a remarkable large Stokes shift. The investigated fluorophores were dispersed in a transparent polyurethane resin, providing a possible luminescent low-cost material for down-shifting conversion. An analysis based on the chemical structures and spectroscopic data, both in solution and polymeric medium, is reported to address the best strategies to optimize the photophysical properties and prevent aggregation. Finally, optimized polyurethane-based films prepared with compounds 2 and 3 were tested as a luminescent coating on a commercial photodiode, enabling their technological application.

In this work, optically active devices are fabricated by Digital Light Processing (DLP) 3D printing technology employing copper-iodide photoluminescent clusters as smart dyes in the photocurable formulation. These compounds are easy to synthesize, low cost and possess large stoke shift, thermochromic and rigidochromic properties, which make them particularly appealing for the development of optical devices. By dispersing such compounds in photocurable formulations, the same properties are transferred to polymeric materials, enabling the production of a large range of devices. Absorbing in the UV range and emitting in the visible range, those clusters show twofold advantages: on the one hand, competing with the photoinitiator for the light absorption, they allow a better control of the photopolymerization process, enabling the fabrication of precise structures; on the other hand, these possess aesthetic properties, being transparent and then emitting light when irradiated. At last, functional structures, such as 3D printed polymeric waveguides (PWGs) and downshifting devices, are fabricated and investigated but even other uses can be envisaged, such as cryogenic optical thermometers.

Perovskite solar cells are a hot topic of photovoltaic research, reaching, in few years, an impressive efficiency (25.5%), but their long-term stability still needs to be addressed for industrial production. One of the most sizeable reasons for instability is the doping of the Hole Transporting Material (HTM), being the salt commonly employed as a vector bringing moisture in contact with perovskite film and destroying it. With this respect, the research focused on new and stable “dopant-free” HTMs, which are inherently conductive, being able to effectively work without any addition of dopants. Notwithstanding, they show impressive efficiency and stability results. The dopant-free polymers, often made of alternated donor and acceptor cores, have properties, namely the filming ability, the molecular weight tunability, the stacking and packing peculiarities, and high hole mobility in absence of any dopant, that make them very attractive and a real innovation in the field. In this review, we tried our best to collect all the dopant-free polymeric HTMs known so far in the perovskite solar cells field, providing a brief historical introduction, followed by the classification and analysis of the polymeric structures, based on their building blocks, trying to find structure–activity relationships whenever possible. The research is still increasing and a very simple polymer (PFDT–2F–COOH) approaches PCE = 22% while some more complex ones overcome 22%, up to 22.41% (PPY2).

Increasing the photocurrent is one of the main objectives of the current research on aqueous photovoltaic cells, the emerging green, alternative technology in solar energy conversion devices. In such a scenario, this work deals with the thorough understanding of the electrochemical and photoelectrochemical effects of the TiCl4 treatment onto TiO2 electrodes, a well-known process for traditional dye-sensitized solar cells, and here, to our knowledge, investigated for the first time in water-based systems. From the quantitative evaluation of the photoelectrochemical parameters, it emerges that the TiCl4 treatment beneficially affects the photovoltaic parameters: it doubles the sunlight conversion efficiency values, inhibits the recombination of photogenerated electrons with oxidized redox mediator ions, and ensures stable and reproducible cell performance at the laboratory scale. (C) 2019 Elsevier Ltd. All rights reserved.

The aim of this work was to investigate the influence of morphology on its electrochemical properties by comparing ZnO nanostructures in the forms of tetrapods of different sizes, nanorods, and nanoparticles. ZnO tetrapods were prepared by the combustion method and separated into two fractions by size, ruling out the influence of synthesis conditions. Structural and morphological properties of different ZnO nanostructure morphologies were identified by using various characterization techniques: scanning and transmission electron microscopies (SEM and TEM), X-ray powder diffraction (XRD), nitrogen adsorption/desorption measurements at 77 K, and UV-vis spectroscopy (UV-vis). Analysis of electrochemical properties showed the highest active surface area of 0.095 cm2 and the lowest peak separation value of 61.7 mV for large ZnO tetrapods, which are close to the theoretical values. The correlation between the pore size in different ZnO nanostructures because of packing and their electrochemical properties is established. We expect that the detailed analysis of ZnO nanostructures conducted in this study will be advantageous for future electrochemical and biosensing applications of these materials.

Three aromatic diimine ligands and the corresponding homoleptic copper(I) and copper(II) complexes have been synthesized and characterized. The copper(II) derivatives are stabilized by an ancillary chlorido ligand. The nature of the chelating ligand seriously impacts the photophysical and electrochemical properties of the complexes. The substitution of the pendant methyl groups with methoxy influences the coordination geometry of the complexes, resulting in an intramolecular dynamic equilibrium between different coordination modes (i.e. nitrogen and oxygen binding), proved by variable-temperature 1H-NMR measurements. As a proof of concept, the most promising complexes were employed as redox mediators in semi-transparent dye-sensitized solar cells. Once implemented in devices, the nature of the ligand plays a crucial role: the methoxy-substituted derivatives appear upon severe ligand exchange with tert-butylpyridine, resulting in an unexpectedly high open circuit voltage.

Squaraine dyes are potential photosensitizers in photodynamic therapy (PDT) due to their ability to release reactive oxygen species (ROS) and cause DNA damage. For this reason, the evaluation and determination of the type of interaction between squaraines and DNA is of the utmost importance. In this study different spectroscopic techniques such as UV–Vis and fluorescence spectroscopies were used to investigate the type of interaction that occurs between two photosensitizers (halogenated squaraines, i.e. Br-C4 and I-C4) and calf thymus DNA (ctDNA). Squaraines were found to bind ctDNA externally following a minor groove binding as they were able to replace Hoechst (a classic groove binder) from the groove of DNA. This binding mode was further supported by iodide quenching studies, ionic strength assay and Florescence Resonance Energy Transfer. Moreover, association (KA) and dissociation (KD) constants were obtained and compared with constants of well-known groove binders.

Cyanine Dyes (CD) are a functional class of organic molecules used in several applications ranging from photography to bioimaging. Most well-known features of CDs reside on high molar extinction coefficients up to 105 L mol-1cm-1 and on the absorption spectra, ranging from 500 to 1000 nm, which can be fine-tuned both by extending the length of the central methylene bridge or by modulating the terminal heterocycles. In the last decades, new synthetic methodologies, namely microwave-assisted and the solid-phase procedure, have been developed to overcome the limitation of the classical synthetic protocols. While the microwave approach usually reduces the exposure time of the reagents and products to thermal degradation, the solid-phase methodology allows easier synthetic protocols, which are translated into higher yields and simpler products purification. In the present review, a comprehensive analysis of the solid-phase methods for the synthesis of asymmetrical CDs is discussed, with a critical evaluation of the difference among the currently available solid-state approaches.

It is well known that the safety and efficacy profile of an inhaled cortocosteroid (ICS) is influenced by the pharmacokinetic properties and associated pharmacodynamic effects of the drug. Freely circulating, protein unbound, and active ICS can cause systemic adverse effects. Therefore, a detailed investigation of drug-protein interaction could be of great interest to understand the pharmacokinetic behaviour of corticosteroids and for the design of new analogues with effective pharmacological properties. In the present work, the interaction between some corticosteroids and human serum albumin (HSA) has been studied by spectroscopic approaches. UV–Vis spectroscopy confirmed that all the investigated corticosteroids can bind to HSA forming a protein-drug complex. The intrinsic fluorescence of HSA was quenched by all the investigated drugs, which was rationalized in terms of a static quenching mechanism. The thermodynamic parameters determined by the Van’t Hoff analysis of the binding constants (negative ΔH and ΔS values) clearly indicate thathydrogen bonds and van der Waals forces play a major role in the binding process between albumin and betamethasone, flunisolide and prednisolone, while hydrophobic forces may play a major role in stabilizing albumin-triamcinolone complexes.

A series of methoxylated imidazo[1,5-a]pyridines is presented and their optical and electrochemical properties investigated and interpreted on the basis of density functional theory calculations. The photophysical properties are discussed in relation to the chemical structure. The key role of the 1,3 substitutions on the imidazo[1,5-a]pyridine nucleus on rotational barriers and on frontier molecular orbitals is discussed in relation to the experimental hyperchromic effect, photoemission quantum yield and electrochemical properties. Depending on the position of the introduced methoxy substituents on the imidazo[1,5-a]pyridine nucleus, we are able to tune the Stokes shift and to increase the emission quantum yield from 22% to 50%.

A facile double condensation procedure, through both standard and microwave heating, provides a versatile one step approach for the synthesis of multidentate nitrogen heterocyclic ligands containing the imidazo[1,5-a]pyridine moiety. The obtained compounds show interesting optical properties: blue fluorescent emissions, moderate quantum yields and large Stokes shifts, enabling their technological application.

A series of 1,3-diarylated imidazo[1,5- a ]pyridine derivatives were synthesized in high yields by a one-pot, three components, condensation of phenyl(pyridin-2-yl)methanone with several aldehydes in the presence of ammonium acetate. These compounds were characterized by spectroscopic and crystallographic techniques and their optical properties were discussed in relation to their chemical structures. Absorption and fluorescence spectra generally show two absorption maxima around 310 nm and 350 nm and an emission maximum between 460 and 550 nm with a remarkable Stokes' shift range of 90–166 nm. Moreover, depending on the chemical structure of the substituent in position 3, we were able to tune the quantum yields (Φ) in solution from 6.4% to 38.5%. Finally, the 1-phenylimidazo[1,5- a ]pyridine substituted with a 3-(2-methoxyphenyl) group (large Stokes' shift, high Φ) was dispersed in a transparent thermosetting polyurethane resin giving a luminescent low cost material.

Hybrid squaraine-SiO2 nanoparticles extremely homogeneous in size (50 ± 2 nm), and with photoluminescent emission in the optical tissue window, were prepare by using the reverse microemulsion technique. Three different high quantum-yield squaraine dyes were used and the photophysical behavior of the prepared samples were qualitatively and quantitatively studied, by steady state and time-resolved photoluminescence, in order to establish structure-property relationships useful for the optimization of the preparation method. These squaraine dyes are insoluble in water and suffer a severe decrease of quantum yield if derivatized with polar groups. The role of the hydrophilicity of the dye-APTS adduct in ruling its dispersion in the nascent silica matrix was confirmed, and the possibility to improve the tuning of the process by properly administration of the adduct with the co-surfactant was demonstrated.

Since the introduction of Perovskite Solar Cells, their photovoltaic efficiencies have grown impressively, reaching over 25%. Besides the exceptional efficiencies, those solar cells need to be improved to overcome some concerns, such as their intrinsic instability when exposed to humidity. In this respect, the development of new and stable Hole Transporting Materials (HTMs) rose as a new hot topic. Since the doping agents for common HTM are hygroscopic, they bring water in contact with the perovskite layer, thus deteriorating it. In the last years, the research focused on “dopant-free” HTMs, which are inherently conductive without any addition of dopants. Dopant-free HTMs, being small molecules or polymers, have still been a relatively small set of compounds until now. This review collects almost all the relevant organic dopant-free small-molecule HTMs known so far. A general classification of HTMs is proposed, and structure analysis is used to identify structure–property relationships, to help researchers to build better-performing materials.

Aqueous dye-sensitized solar cells (DSSCs) are emerging as a promising alternative to enhance both the lifetime and environmental friendliness of traditional DSSCs. Herein, a cobalt-based, jellified (with xanthan gum) aqueous electrolyte, leading to a valuable efficiency exceeding 4% (V-OC = 847 mV, J(SC) = 6.73 mA cm(-2), fill factor = 74%), is reported. Design of experiment is used to precisely and significantly study, at a multivariate level, the effects produced by the Co2+ concentration, Co2+/Co3+ ratio, and xanthan gum amount modifications on the overall photovoltaic parameters of lab-scale solar cells.

Peptide nucleic acids (PNAs) are among the most interesting and versatile artificial structural mimics of nucleic acids and exhibit peculiar and important properties (i.e. high chemical stability, and a high resistance to cellular enzymes and nucleases). Despite their unnatural structure, they are able to recognize and bind DNA and RNA in a very high, specific and selective manner. One of the most popular, easy and reliable method to measure the stability of PNA-DNA hybrid systems is the melting temperature but the thermodynamic data are obtained using a big quantity of materials failing to provide information on the kinetics of the interaction. In the present work, the PNA decamer 6 , with the TCACTAGATG sequence of nucleobases, and the corresponding fluorescent PNA-FITU (fluorescein isothiourea) decamer 8 were synthesized with standard manual Boc-based chemistry. The interaction of the PNA-FITU with parallel and antiparallel DNA has been studied by stopped-flow fluorescence, which is proposed as an alternative technique to obtain the kinetic parameters of the binding. The great advantage of using the stopped-flow technique is the possibility of studying the kinetics of the PNA-DNA duplex formation in a physiological environment. In particular, fluorescence stopped-flow technique has been exploited to compare the affinity of two PNA-DNA duplexes since it can discriminate between parallel and antiparallel DNA binding.

Highly fluorinated gemini surfactants are relevant in pharmaceutical field, owing their ability to deliver genes to the respiratory or to the biliar epithelium, where hydrogenated interfering surfactants are present. We report for the first time the thermodynamic properties of the solutions of 1,1′-Bis(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-2,2 n-methylenebispyridinium dichloride (n = 4, 8, 12). The gene delivery ability of the dichlorides and the structure of the DNA nanoparticles are strictly related to their solution enthalpic properties, resulting in a very sensitive probe of the behaviour of the molecule in solution. Dilution enthalpies, density and sound velocities vs. molality for dichlorides and dimethanesulfonates with different spacer length, n, were measured. The evaluation of apparent and partial molar enthalpies as a function of concentration of the dimethanesulfonate suggests that the effect of the counterion is additive and the values obtained for the hydrogenated surfactants can be transferred to the fluorinated ones, allowing the prediction of enthalpic properties in solution. No evidence of the structure change in solution is found in the trends of volumetric properties vs. m. and the group contribution of the CH2 for both the dichlorides and the dimethanesulfonates results additive as well as the effect of the counterion. The adiabatic molar compressibilities seem to be independent from the counterion and show in micellar region a plateau value much greater than in the case of the more traditional hydrogenated gemini surfactants, indicating a less compact structure of the micelles, probably due to the repulsion between hydrogenated and fluorinated moieties of the molecules.

Polymethine dyes as photosensitizers for dye-sensitized solar cells (DSCs) are reviewed. The review provides a summary of design strategies, the main synthetic routes, and the optical and photovoltaic properties of polymethine dyes applied in hybrid photovoltaics. In particular, we focus on cyanine and squaraine dyes and their structure–properties relationships, highlighting the role of the active molecule design on device performance.

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are two innovative classes of porous coordination polymers. MOFs are three-dimensional materials made up of secondary building blocks comprised of metal ions/clusters and organic ligands whereas COFs are 2D or 3D highly porous organic solids made up by light elements (i.e., H, B, C, N, O). Both MOFs and COFs, being highly conjugated scaffolds, are very promising as photoactive materials for applications in photocatalysis and artificial photosynthesis because of their tunable electronic properties, high surface area, remarkable light and thermal stability, easy and relative low-cost synthesis, and structural versatility. These properties make them perfectly suitable for photovoltaic application: throughout this review, we summarize recent advances in the employment of both MOFs and COFs in emerging photovoltaics, namely dye-sensitized solar cells (DSSCs) organic photovoltaic (OPV) and perovskite solar cells (PSCs). MOFs are successfully implemented in DSSCs as photoanodic material or solid-state sensitizers and in PSCs mainly as hole or electron transporting materials. An innovative paradigm, in which the porous conductive polymer acts as standing-alone sensitized photoanode, is exploited too. Conversely, COFs are mostly implemented as photoactive material or as hole transporting material in PSCs.

A microwave-assisted method for the preparation of a wide color range of 2,3,3-trimethylindolenine-based squaraines and their intermediates is described. This practical approach allows the rapid preparation of both symmetrical and nonsymmetrical squaraine dyes, reducing reaction time from days to minutes with more than 2-fold improvement in product yields when compared to conventional methods.

Photodynamic therapy (PDT) efficiency is affected by the nature of the binding between the photosensitizer and serum albumin. The kinetic interaction between two potential PDT dyes with bovine serum albumin was studied providing not only the rate constants but also demonstrating that the kinetic of the interaction of the two dyes is very different.

The interaction with a model membrane, the formation of DNA nanoparticles, and the transfection ability of a homologous series of bispyridinium dihexadecyl cationic gemini surfactants, differing in the length of the alkyl spacer bridging the two pyridinium polar heads in the 1 and 1' positions (P16-n with n = 3, 4, 8, 12), have been studied by means of differential scanning calorimetry (DSC), atomic force microscopy, electrophoresis mobility shift assay, and transient transfection assay measurements. The results presented here show that their performance in gene delivery is strictly related to their structure in solution. For the first time the different transfection activities of the compounds can be explained by referring to their thermodynamic properties in solution, previously studied. The compound with a spacer formed by four carbon atoms, showing unexpected enthalpic properties vs concentration in solution, is the only one giving rise to a transfection activity comparable to that of the commercial reagent, when formulated with L-α-dioleoylphosphatidylethanolamine. We suggest that P16-4 behaves like molecular tongs able to grip basic groups near each other, allowing the formation of compact and nearly spherical DNA particles. The compound with the longest spacer gives rise to loosely condensed structures by forming a sort of bow, not able to give rise to transfection notwithstanding the double positive charge of the molecule. On the other hand, DSC measurements on synthetic membranes show that the compounds with the shortest spacers (three and four methylene groups) practically do not interact with the 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine membrane, while compounds P16-8 and, particularly, P16-12 induce the formation of surfactant-rich and surfactant-poor domains in the membrane, without showing any peculiarity for compound P16-4. This could suggest that the mechanisms involved in the interaction with the model membrane and in gene delivery are substantially different and could strike a blow for an endocytosis mechanism for the internalization in the cell of the DNA nanoparticles.

Herein, the synthesis of a new family of squaraines (SQs) and their application in p-type dye-sensitized solar cells (DSSCs) is presented. In particular, two sets of SQs were designed featuring either two or four anchoring carboxylic groups combined with either oxygen or dicyanovinyl central groups. The SQs were characterized by using a joint theoretical, photophysical, and electrochemical approach. Importantly, the presence of different central groups forces a frozen cis (dicyanovinyl group) or a trans (oxygen group) SQ conformation. Based on the latter, the current work enables a direct comparison between cis and trans isomers as well as the impact of a different number of anchors. Considering their electron-accepting and light-harvesting character, they were tested in NiO-based DSSCs. Photocurrent-voltage, incident photon-to-current conversion efficiency (IPCE), and electrochemical impedance spectroscopy measurements were performed. By virtue of their different symmetry, stereochemistry, and number of carboxylic groups, altered adsorption behavior onto NiO electrodes as well as diverse charge injection and charge recombination dynamics were noted under operation conditions. SQs with four linkers in a frozen cis isomerism show the best charge collection properties among the investigated SQs, providing a valuable guideline for the molecular design of future SQs for p-type DSSCs. In addition, we assembled tandem DSSCs featuring SQ/NiO photocathodes and N719/TiO2 photoanodes. The IPCE of the resulting tandem DSSCs implies light harvesting throughout most of the visible part of the solar spectrum owing to the complementary absorption features of SQ and N719.

We report here on the preparation and on the electronic properties of a panchromatic Ru(ii) sensitizer based on a new ligand which allows for higher molar extinction coefficients in the visible and better performances (32% efficiency improvement) over conventional "black dye" in transparent DSSC.

International audience; By optimizing the lithium concentration in an electrolyte to 50 mmol L(-1 )and the dye-to-chenodeoxychollc acid ratio in a VG1-based dye solution, we achieved 4.7% power conversion efficiency under standard AM 1.5G conditions. In addition to this performance, we herein discuss the role played by lithium in the electrolyte and its interplay in the charge transfer processes from ms to fs dynamics. Based on electrochemical impedance spectroscopy, photoluminescence and pump-probe transient absorption spectroscopy, we conclude that although lithium increases the electron diffusion length, this has no satisfactory impact on electron injection and even slows dye regeneration. This study provides evidence that lithium is not only specifically adsorbed on the surface of TiO2 but prompts a molecular reorganization of the self-assembled dye monolayer, forming harmful H-aggregates.

The connection between heterocyclic systems by forming new C C bond is a relevant topic for the easy preparation of intermediates and functional dyes for technological applications. Several methods were developed in the last decades and the urge for sustainable synthetic chemical methods pushed us to prepare thienylpyridines and two thienylbipyridine ligands by the Suzuki reaction in aqueous CTAB micellar medium and in presence of a Pd catalyst. These intermediates can be found as component of dyes and functional thiophene monomers. Reaction conditions were optimized under both thermal and microwave (MW) activation obtaining good yields (70–93%) using Pd(PPh3)4 as catalyst. Two thienylbipyridine ligands were prepared and the transformation of one of them into a terthiophene-based bipyridine ligand was easily obtained by almost green methods and with very good yield. This clean and sustainable method can be proposed as a green step to obtain intermediates and final dyes for technological applications, such as CO2 reduction, in gram-multigram scale.

Biological and thermodynamic properties of a new homologous series of highly fluorinated bispyridinium cationic gemini surfactants, differing in the length of the spacer bridging the pyridinium polar heads in 1,1' position, are reported for the first time. Interestingly, gene delivery ability is closely associated with the spacer length due to a structural change of the molecule in solution. This conformation change is allowed when the spacer reaches the right length, and it is suggested by the trends of the apparent and partial molar enthalpies vs molality. To assess the compounds' biological activity, they were tested with an agarose gel electrophoresis mobility shift assay (EMSA), MTT proliferation assay and Transient Transfection assays on a human rhabdomyosarcoma cell line. Data from atomic force microscopy (AFM) allow for morphological characterization of DNA nanoparticles. Dilution enthalpies, measured at 298K, enabled the determination of apparent and partial molar enthalpies vs molality. All tested compounds (except that with the longest spacer), at different levels, can deliver the plasmid when co-formulated with 1,2-dioleyl-sn-glycero-3-phosphoethanolamine (DOPE). The compound with a spacer formed by eight carbon atoms gives rise to a gene delivery ability that is comparable to that of the commercial reagent. The compound with the longest spacer compacts DNA in loosely condensed structures by forming bows, which are not suitable for transfection. Regarding the compounds' hydrogenated counterparts, the tight relationship between the solution thermodynamics data and their biological performance is amazing, making "old" methods the foundation to deeply understanding "new" applications.