Asphaltene aggregation mechanism is still a nebulous and controversial issue. Many authors argue that the aggregation of its components is due to π-stacking interactions, nonetheless, alkyl chains, heteroatoms, and even acidic groups are also constituents of asphaltenes and can play an important role in the chemistry of asphaltene. Excimers from pyrene are easily detected by fluorescence and were used in the current study to probe the effect of the side chain on the π-stacking capacity of pyrene. Pyrene was acylated with acyl chains varying from two to twelve carbon atoms, and the effect of the variation of the acyl chain length on excimer formation was followed by fluorescence emission spectroscopy. The results revealed that as the side chain grows from two to twelve carbon atoms the excimer/monomer ratio decreases and the excimer heat of formation drops from ΔH = -6.00 to -1.29 kcal mol-1. Further, the crystal structure of octanoyl pyrene (PC8) indicates that in the crystal structure, the aromatic moiety faces the acyl chain. This result was corroborated by density functional theory (DFT) calculations. Finally, the results were compared with two different asphaltenes and indicate that π-stacking cannot be assumed as the main driving force for asphaltene aggregation. issue πstacking π stacking interactions nonetheless heteroatoms spectroscopy excimermonomer monomer 6.00 600 6 00 -6.0 1.29 129 1 29 -1.2 mol1. mol1 mol 1. mol-1 Further PC8 PC (PC8 DFT (DFT calculations Finally 6.0 60 0 -6. 1.2 12 2 -1. mol- (PC 6. -6 -1 -

Niobium pentoxide shows an interesting reactivity that allows the control of different aspects of its morphology and chemistry. In this study, Nb2O5 nanoparticles were modified with protoporphyrin IX (PPIX) and tris(ethynylphenyl) pyrene derivative (PyPh3) by using 3-aminopropyltriethoxysilane as linkage group and used as photosensitizers against lung cancer. The antitumor photoactivity against the A549 tumor cell line as a model of in vitro study showed half maximal inhibitory concentration (IC50) ca. 15 μmol L-1 for both materials and the absence of dark activity, indicating the viability of dye-modified Nb2O5 as a photodynamic therapy (PDT) agent. chemistry NbO Nb O Nb2O PPIX (PPIX trisethynylphenyl tris ethynylphenyl tris(ethynylphenyl PyPh3 PyPh (PyPh3 3aminopropyltriethoxysilane aminopropyltriethoxysilane 3 cancer A A54 IC50 IC (IC50 ca 1 L1 L L- activity dyemodified dye PDT (PDT agent (PyPh A5 IC5 (IC5 (IC

This study shows a preparation and evaluation of a new non-expensive TiO2 based photocatalyst built over sand grains surfaces as an alternative green technology for water treatment. The semiconductor covalently bonded to the silica sand grains (sand@TiO2) prepared by hydrolysis of isopropoxide orthotitane over sand grains, showed a high surface area 296 m2 g-1 and a high reaction rate for methylene blue (MB) photodegradation (0.064 min-1), on steady state condition by using 3 g of sand@TiO2 and an MB solution (20 mL, 3 × 10-5 mol L-1) or ciprofloxacin hydrochloride (CIP) solution (20 mL, 1.9 × 10-3 mol L-1). Under UV irradiation with a medium pressure Hg lamp, the total MB removal reached 70% after 7 min and 45% for CIP in 60 min. Further, the photocatalyst showed to be a promising reusable material for removal of ciprofloxacin hydrochloride antibiotic (CIP) on wastewater. This new material appears as a new promising low cost and low impact reusable catalyst for water treatment.