Spectroscopic characterization of triplet (2- and 3-thienyl)carbenes and development, implementation, and testing of a web-based tool for use in middle and high school classrooms

Photolysis (lambda> 543 nm) of 3-thienyldiazomethane (1) yields triplet s-Z and s-E 3-thienylcarbene (s-E 5 and s- Z 5), as characterized by IR, UV/vis, and EPR spectroscopy. The EPR spectra of s-E 5 and s-Z 5 are markedly different, and proved to be unusual. NBO calculations and a Mulliken spin density analysis were carried out to explore the complex nature of these spectra.;In an effort to obtain a comparison to the unusual EPR spectra of 3-thienylcarbene and to explore how the photochemistry of the system would be perturbed, methyl and deuteriomethyl analogs of the parent compounds were studied. Photolysis (lambda> 534 nm) of 3-thienyl-1-diazoethane (16) yields only one triplet 3-thienylethylidene rotamer (s-E 21), as characterized by UV/vis, and EPR spectroscopy. EPR and UV/visible signals attributed to s-E 21 decreased by approximately 50% after sitting in the dark for 3.5 days, suggesting a "thermal" reaction at 10 K. Photolysis (lambda > 534 nm) of 3-thienyl-1-diazoethane- d3 (16-d3) yields triplet s-E 3-thienylcarbene-d3 (s-E 21-d3), as characterized by IR, UV/vis, and EPR spectroscopy. Analogous to the photochemistry of 16, s-Z 21 -d3 was absent from the matrix. s- E 21-d3 is thermally stable at 10 K.;Our attempts at isolating a 2-thienylsubstituted triplet carbene in this family had been unsuccessful up to this point. Spectroscopic detection of a 2-thienylcarbene derivative was realized with the characterization of 2-benzo[b]thienylethylidene (34) and 2-benzo[b]thienylethylidene-d3 (34-d3) by IR, UV/vis, and EPR spectroscopy.;The development and implementation of "Today's Science for Tomorrow's Scientist" (TSTS), a Web site that presents current science research in a format suitable for middle school and high school classrooms is discussed. The information presented on TSTS correlates with the National Science Education Standards, allowing for ease of use by teachers. TSTS was beta tested and then fully implemented in middle schools and high schools in the Madison, WI area. The data show that both middle school and high school students improve by a significant amount from content pre survey to content post survey after viewing TSTS.