No abstract

Herein, we present the light-induced synthesis and characterization of a La 3+ /spiropyran derivative complex (LaMC) and its application as a catalyst when incorporated into electrospun polycaprolactone (PCL) fibers. In addition to experimental methods, computational calculations were also essential to better understand the structure and electronic characteristics of LaMC. The LaMC complex was identified as a 10-coordinated structure with the La 3+ ion coordinated by four oxygens from the phenolate and the carbonyl of the carboxyl acid group from both MC ligands and by six oxygens from three nitrate ligands. In addition, LaMC was capable of getting reversibly isomerized by UV or visible light cycling. All PCL fibers were successively obtained, and their morphologies, surface properties, and catalytic behavior were studied. Results showed that PCL/LaMC fibers were capable of catalyzing bis(2,4-dinitrophenyl)phosphate degradation efficiently. Complete hydrolysis was accomplished in only 1.5 days relative to the half-life time of 35 days for the uncatalyzed hydrolysis at pH 8.1 and 25 °C.

This work reports the catalysis of bare silica materials (MCM-41, SBA-15, and silica gel) for the complete hydrolyses of bis(2,4-nitrophenyl)phosphate (BDNPP) and bis(4nitrophenyl)phosphate (BNPP), which share the same phosphate diester chemical core with important biological molecules, DNA and RNA, and toxic substances like EA2192 and anatoxin-a(s). Catalytic effects above 7000-fold were observed for the hydrolysis of BNPP, which were consistent with a concerted S N 2(P) mechanism under the action of siloxide and silanol groups that provide water activation by general base catalysis and leavinggroup departure stabilization by general acid catalysis, respectively. We also observed that product formation follows a sigmoidal behavior as a result of catalytic effect enhancement following an induction period. This effect is discussed considering cooperative effects caused by silica hydration, which is unchanged upon material reuse affording strong catalytic effects for phosphate diester hydrolyses and no induction periods.