Tetrazole as a New Anchoring Group for the Functionalization of TiO₂ Nanoparticles: A Joint Experimental and Theoretical Study

Functional hybrid materials are an important tool for generating original architectures featuring desirable properties for multiple applications. The success in creating innovative materials with valuable functionalities relies on the close interaction between the organic and inorganic parts of the hybrid system. Herein, we report the use of tetrazole as an anchoring group for the photosensitization of TiO₂ nanoparticles by an organic chromophore and the related performance in dye-sensitized solar cells. The interaction mode between the tetrazole motif and TiO₂ was thoroughly investigated by various techniques. The overall study reveals that the optoelectronic and photovoltaic properties of the dye featuring tetrazole rival those of an analogue bearing a carboxylic acid function, even leading to significantly enhanced photovoltage in the device. These results demonstrate the effectiveness of the tetrazole functional group as a serious alternative anchoring group for organic photosensitizers in hybrid materials for energy

Average values of the binding constants for the studied systems.

<p><i>Average K values calculated by using the Benesi–Hildebrand equation for all the isophorone-DNA systems studied</i>.</p><p>Average values of the binding constants for the studied systems.</p

Chemical structures.

<p>Structures of: A) Isoa, B) Isob and C) Isoc.</p

Stern-Volmer plots for the fluorescence quenching of Isoa-c by DNA.

<p>Plot of the ratio of the isophorone derivatives fluorescence intensity before and after incremental addition of DNA as a function of the quencher concentration for the determination of the Stern-Volmer quenching rate constant.</p

Effect of the isophorone derivatives on the DNA conformation.

<p>Circular dichroism (CD) spectra of DNA (30.9 μM) treated with: A) 0.0 (black line), 12.82 (red line), 38.07 (blue line), 62.81(green line) μM (curves 1–4) of Isoa, B) 0.0 (black line), 12.82 (red line), 38.07 (blue line), 62.81(green line) μM (curves 1–4) of Isob, C) 0.0 (black line), 12.82 (red line), 38.07 (blue line), 62.81(green line) μM (curves 1–4) of Isoc.</p

Plot of log [(F₀-F)/F] <i>vs</i>. log [DNA].

<p>Determination of the binding constant and number of binding sites for the Iso-DNA systems.</p

Binding constant determination.

<p>Plots of 1/(A-A₀) <i>vs</i>. 1/Isophorone concentration for DNA and their isophorone complexes. A₀ is the absorbance of DNA (at 260 nm) and A is the absorbance after isophorone addition.</p

Binding stoichiometry.

<p>Mole ratio plot of Isoa-DNA system.</p

Red Emitting Neutral Fluorescent Glycoconjugates for Membrane Optical Imaging

A family of neutral fluorescent probes was developed, mimicking the overall structure of natural glycolipids in order to optimize their membrane affinity. Nonreducing commercially available di- or trisaccharidic structures were connected to a push–pull chromophore based on dicyanoisophorone electron-accepting group, which proved to fluoresce in the red region with a very large Stokes shift. This straightforward synthetic strategy brought structural variations to a series of probes, which were studied for their optical, biophysical, and biological properties. The insertion properties of the different probes into membranes were evaluated on a model system using the Langmuir monolayer balance technique. Confocal fluorescence microscopy performed on muscle cells showed completely different localizations and loading efficiencies depending on the structure of the probes. When compared to the commercially available ANEPPS, a family of commonly used membrane imaging dyes, the most efficient probes showed a similar brightness, but a sharper pattern was observed. According to this study, compounds bearing one chromophore, a limited size of the carbohydrate moiety, and an overall rod-like shape gave the best results