Poly methyl methacrylate films containing metallophthalocyanines in the presence of CdTe quantum dots: Non-linear optical behaviour and triplet state lifetimes

Enhancing the FRET by tuning the bandgap of acceptor ternary ZnCdS quantum dots

In this article, we report the band gap tuning of ternary ZnCdS quantum dots (QDs) by varying the concentration of the capping ligand, mercaptoacetic acid (MAA). The functionalization of QDs leads to the control of their size and band gap due to the quantum confinement effect, causing blue shift in the absorption and photoluminescence (PL) spectra with a gradual change in the concentration of the capping ligand from 0.5 to 2.5 M. Ensulizole (2-phenylbenzimidazole-5-sulfonic acid) is an important organic ultraviolet (UV) filter that is frequently used in sunscreen cosmetics. An effective overlapping of the PL spectrum of ensulizole and the absorption spectrum of QDs with 2.5 M MAA is achieved. A formidable decrease in the PL intensity and the PL lifetime of ensulizole promotes an efficient Förster resonance energy transfer (FRET) from sunscreen ensulizole to the QDs. The magnitude of the FRET efficiency (E) is ∼70%. This very high value of E is the signature of the existence of a very fast energy transfer process from ensulizole to the MAA functionalized ZnCdS QDs. The dyad system consisting of ZnCdS QDs and ensulizole sunscreen can serve as a prototype model to develop a better understanding of the photochemistry of ensulizole and consequently the formulation of more efficient sunscreen cosmetics.

Optical limiters with improved performance based on nanoconjugates of thiol substituted phthalocyanine with CdSe quantum dots and Ag nanoparticles

Grafting of thiolated phthalocyanine onto quantum dots and nanoparticles provided conjugates with prominent optical limiting.

Improvement of nonlinear optical properties of phthalocyanine bearing diethyleneglycole chains: Influence of symmetry lowering vs. heavy atom effect

This paper reports the successful synthesis of the low symmetry phthalocyanines: metal-free 2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-[Formula: see text]-butoxyphthalocyanine 1H[Formula: see text] and its zinc complex 1Zn along with their nonlinear optical (NLO) behavior in solution and in thin films. 1H NMR investigations evidenced of higher dissymmetry of electronic density in 1H[Formula: see text] in comparison with 1Zn. This dissymmetry is responsible for unusually higher values of Im[[Formula: see text]]/[Formula: see text], [Formula: see text], and [Formula: see text] for 1H[Formula: see text]in contrast to 1Zn, where the notable effect of heavy-metal enhancement of ISC was expected. Both compounds showed Im[[Formula: see text]]/[Formula: see text] values of the order of 10[Formula: see text] in chloroform which are higher in comparison to the symmetrical octabutoxyphthalocyanine H2[(BuO)8Pc]. NLO properties of 1H[Formula: see text] were improved via its incorporation into polycarbonate polymeric matrix together with CdSe@CdS-TOPO quantum dots. In such composite the value of Im[[Formula: see text]]/[Formula: see text] was almost three times higher in comparison with 1H[Formula: see text] solution in chloroform. The obtained composites are expected to be perspective components of optical materials, capable of protection against strong light irradiation.

Nonlinear Optical Materials for the Smart Filtering of Optical Radiation

The control of luminous radiation has extremely important implications for modern and future technologies as well as in medicine. In this Review, we detail chemical structures and their relevant photophysical features for various groups of materials, including organic dyes such as metalloporphyrins and metallophthalocyanines (and derivatives), other common organic materials, mixed metal complexes and clusters, fullerenes, dendrimeric nanocomposites, polymeric materials (organic and/or inorganic), inorganic semiconductors, and other nanoscopic materials, utilized or potentially useful for the realization of devices able to filter in a smart way an external radiation. The concept of smart is referred to the characteristic of those materials that are capable to filter the radiation in a dynamic way without the need of an ancillary system for the activation of the required transmission change. In particular, this Review gives emphasis to the nonlinear optical properties of photoactive materials for the function of optical power limiting. All known mechanisms of optical limiting have been analyzed and discussed for the different types of materials.