1734-16-3Relevant academic research and scientific papers
Photochemically driven shape changes of crystalline organic nanorods
Al-Kaysi, Rabih O.,Mueller, Astrid M.,Bardeen, Christopher J.
, p. 15938 - 15939 (2006)
Nanorods composed of 9-tert-butylanthroate (9-TBAE) are synthesized using an Al2O3 template and solvent annealing. The rods consist of micron-scale crystalline domains, and UV light induces a [4 + 4] photodimerization that results in a uniform 15% expansion along the rod axis. This is in contrast to random 9-TBAE crystals, which disintegrate under the same conditions. Transmission electron microscopy, atomic force microscopy, and comparison of the X-ray crystal structures of the monomer and photodimer all provide evidence for a mechanism based on a crystal-to-crystal photoreaction leading to an increase in molecular volume. It is likely that the high surface-to-volume ratio in the nanorods provides a strain relief pathway that is absent in larger crystals. Preliminary attempts to reverse the reaction using shorter wavelength light to photodissociate the dimers were only partly successful. These results suggest that crystalline organic nanostructures may provide an efficient way to transform photochemical energy into mechanical motion on the nanometer scale. Copyright
Solid-state photochemical and photomechanical properties of molecular crystal nanorods composed of anthracene ester derivatives
Zhu, Lingyan,Agarwal, Arun,Lai, Jinfeng,Al-Kaysi, Rabih O.,Tham, Fook S.,Ghaddar, Tarek,Mueller, Leonard,Bardeen, Christopher J.
experimental part, p. 6258 - 6268 (2011/11/12)
A series of 9-anthroate esters that can form photoresponsive molecular crystal nanorods is prepared and their properties are investigated. All crystal structures that can support a [4 + 4] photodimerization reaction lead to nanorods that undergo photomechanical deformations without fragmentation. In order to determine the molecular-level motions that give rise to the nanorod photomechanical response, the reaction of anthracene-9-carboxylic acid tert-butyl ester is studied in detail using X-ray diffraction and solid-state NMR techniques. The monomer crystal is well-aligned within the nanorod and reacts to form the photodimer crystal according to first-order kinetics. The solid-state reacted dimer crystal is a metastable intermediate that slowly converts into the low energy dimer crystal structure over the course of weeks. Based on single crystal X-ray diffraction studies and solid-state NMR data, this intermediate structure is likely composed of the [4 + 4] photodimer that has not yet undergone the ester group rotations and repacking is necessary to form the lower energy crystal polymorph that is produced directly by crystallization from solution. Our results show that the photomechanical response of these molecular crystal nanostructures is determined by nonequilibrium intermediate states and cannot be predicted based solely on knowledge of the equilibrium reactant and product crystal structures.
Reductions of challenging organic substrates by a nickel complex of a noninnocent crown carbene ligand
Findlay, Neil J.,Park, Stuart R.,Schoenebeck, Franziska,Cahard, Elise,Zhou, Sheng-Ze,Berlouis, Leonard E. A.,Spicer, Mark D.,Tuttle, Tell,Murphy, John A.
supporting information; experimental part, p. 15462 - 15464 (2011/02/22)
The first crown-tetracarbene complex of Ni(II) has been prepared, and its crystal structure determined. The complex can be reduced by Na/Hg, with an uptake of two electrons. The reduced complex reductively cleaves arenesulfonamides, including those derived from secondary aliphatic amines, and effects Birch reduction of anthracenes as well as reductive cleavage of stilbene oxides. Computational studies show that the orbital that receives electrons upon reduction of the complex 2 is predominantly based on the crown carbene ligand and also that the HOMO of the parent complex 2 is based on the ligand.
EPR studies on carboxylic esters. Part 16. Indirect generation of the elusive radical anions of alkyl anthracene-9-carboxylates
Behrens, Thomas,Bruns, Stefan,Voss, Juergen
, p. 624 - 629 (2007/10/03)
Electroreduction of dioxygen in aprotic media yields superoxide anions O2.-. These highly reactive radical anions easily attack sensitive arenes. It is, therefore, not possible to generate the radical anions of anthracene-9-carboxyli
