Amphiphilic block copolymers based on hydrophobic polysulfides (poly(propylene sulfide), PPS) and hydrophilic polyethers (poly(ethylene glycol), PEG) have been used to solubilize and disperse single-walled carbon nanotubes (SWNTs). The obtained highly concentrated aqueous dispersions are stable for months. The factors that affect the dispersant activity of the studied block copolymers have been characterized, and comparisons with the much more investigated oxygen analogues (Pluronics) are reported. The biocompatibility and the stability after dilution of the most representative suspensions have been investigated as prospective drug carriers.

Quantitative characterization of quantum states in complex molecular systems is a rather complicated task because of the necessity of maintaining the pure quantum definition of a state interacting with a configurationally complex molecular environment. Unfortunately, many of the "observables" that are of interest for a chemist, typically dealing with "complex objects", belong to the above class and their theoretical modeling may represent a hard task. In this respect, we have developed a new theoretical methodology, "perturbed matrix method", essentially based on the perturbation theory whose main aim is the characterization of the quantum states of a predefined portion of a complex molecular system, e.g., a solute, classically interacting with the environment, e.g., the solvent. This method has been used in this study to systematically characterize, for the first time and in conjunction with experimental observations, the intrinsic nature of pyrene whose vibrational and electronic states are highly sensitive to the nature of molecular environment. More precisely, pyrene shows a strong alteration of spectral intensities upon modification of polarity of the solvent. This property has been extensively used in many experimental studies and has been interpreted in the present study by characterizing pyrene electronic states as fluctuating states strictly connected to the polarity and the fluctuations of the surrounding medium. A correct theoretical modeling has been also obtained and commented for the vertical transitions in different media and also for the vibronic structure for the first transition in water.

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