Daniel J. Sandman

Two-photon fluorescence properties of curcumin as a biocompatible marker for confocal imaging

Two-photon (TP) fluorescence properties of an antioxidant and anti-tumor molecule, curcumin, were investigated. The two-photon absorption (TPA) action cross-section was measured in organic solvents and found to be 6 GM in tetrahydrofuran and 2 GM in dimethyl sulfoxide. The measured TPA cross-section is comparable to that of rhodamine 6G. One-photon and TP confocal microscopy has demonstrated that curcumin is internalized in cells and can be used for imaging applications. Our investigation indicates that curcumin is a viable biocompatible TP fluorescent marker.Two-photon (TP) fluorescence properties of an antioxidant and anti-tumor molecule, curcumin, were investigated. The two-photon absorption (TPA) action cross-section was measured in organic solvents and found to be 6 GM in tetrahydrofuran and 2 GM in dimethyl sulfoxide. The measured TPA cross-section is comparable to that of rhodamine 6G. One-photon and TP confocal microscopy has demonstrated that curcumin is internalized in cells and can be used for imaging applications. Our investigation indicates that curcumin is a viable biocompatible TP fluorescent marker.

Synthetic, Structural, and Electrical Aspects of Molecular and Polymeric Selenium and Tellurium Materials

Abstract The physical and structural concepts concerning organochalcogen-based anisotropic organic metals are summarized, and the rationales which motivate synthetic activity in new selenium and tellurium materials are presented. An overview of our approach to new aromatic molecular and polymeric materials involving direct thermal reaction of new alkali chalcogenide reagents with unactivated aromatic halides is given, and recent applications to the synthesis of tetraselenonaphth-alene (TSeN) and new transition metal diselenolenes based on o-benzenediselenolate (bds) are noted. The crystal and molecular structures of TSeN and (nC4Hg)4N+ Ni(bds)2′ have been determined, as well as their electronic absorption and electron spin resonance spectra and cyclic voltammetric behavior. The reaction of cis-dichloroethylene and sodium diselenide leads to a polymer to which the repeat sequence ←Se-CH=CH-CH-CR-Se→ is assigned, based on elemental analysis and infrared spectrum.

Single-crystal reflection and Raman spectra of the polydiacetylene THD

Abstract The 298 K. Raman and reflection spectra of the polydiacetylene THD, a close structural variant of DCHD, are presented. The polymer double- and triple-bond stretch frequencies are 1485 and 2111 cm −1 , respectively, and the lowest electronic transition peaks at 17600 cm −1 . The reflection spectrum is more reminiscent of the polydiacetylene TCDU than DCHD.

Solid State Polymerization of Diacetylenes Incorporating Ynamine Moiety

Novel ynamine compounds, 5-hydroxy-1-(phenothiazine-10-yl)-1,3-pentadiyne (1), its S-oxide (2) and S-dioxide (3), were prepared. Compound 2 was found to show thermal reactivity to give polydiacetylene, however 1 and 3 did not show any reactivity. Compound 2 stacks along the c axis, forming a columnar structure. The condition of molecular arrangement satisfied Baughmans criterion. Significant intermolecular contact between the oxygen atoms of sulfoxide groups and the adjacent sulfur atoms was recognized.

The Crystal Structure of Tetratellurotetracene (TTeT) and Polymorphism of Tetraselenotetracene (TSeT)

Abstract The crystal structure of TTeT has been determined; salient features include a linear chain structure and very short intermolecular Te-Te contacts. A previously unreported polymorph of TSeT was found to be isomorphous to TTeT. These data, taken with the reported data for TTT, indicate a series of three crystals each with a lattice constant which is approximately twice the van der Waals radius of the chalcogen.

Second-order nonlinear optical properties of a photocrosslinkable epoxy-based polymer

The synthesis and characterization of a novel epoxy-based photocrosslinkable nonlinear optical (NLO) polymer exhibiting enhanced thermal stability is reported. The synthesized polymers show spectroscopic properties (NMR, IR, UV) in accordance with the proposed structures. A glass transition temperature (T g ) of 112°C and a thermal degradation temperature (T d ) of 310°C were recorded. The poled polymer film exhibits stable second-order nonlinear optical activity (d 33 = 19.5 pm/V) over a period of 500 h as characterized by the temporal response of the second harmonic signal at room temperature.

Polydiacetylenes and analogies to inorganic semiconductors and graphite

Abstract The crystallography and one-dimensional electronic structure of polydiacetylenes (PDAs) stimulate a variety of chemical and physical studies. 13 C CP-MAS n.m.r. studies of the PDAs from PTS and TCDU as well as 1, 1, 4,-4-tetraphenylbutatriene establish the en-yne bond representation for TCDU and rule out a significant contribution from a butatriene form to the ground state at room temperature. The current status of third-order non-linear optical phenomena in PDAs and the conversion of PDAs to conductive materials by ion implantation is presented. Our anisotropic chemical modification of poly-DCH is conceptually distinguished from the usual charge transfer doping of non-crystalline polymers.

Solid State Polymerization and the Chemical Reactivity of Solid Polydiacetylenes

Abstract The term “design” of a solid state polymerization, taken to imply the necessary crystallographic and mechanistic considerations, is introduced with a view toward discovery and development of new lattice controlled processes. Using examples from known solid state polymerizations, a qualitative discussion of several crystallographic and mechanistic issues is presented. With the caveat that such issues may not be easily separated, a central conclusion appears to be that mechanistic problems associated with initiation and propagation steps may hold the key to progress in this area. While chlorine, aqua regia, and nitric acid convert single crystals of poly-1, 6-di-N-carbazolyl-2, 4-hexadiyne (DCH) to amorphous solids, bromination, which proceeds more rapidly as temperature is lowered, results in a crystalline solid. These reactions are anisotropic and their products are characterized by spectroscopic and crystallographic techniques. It is concluded that the initial reactivity is controlled by carbazo...

Ultraviolet photoelectron spectroscopy study of the thermochromic phase transition in urethane-substituted polydiacetylenes

Threshold solid-state ionization energies determined from ultraviolet photoelectron spectra are reported for the thermochromic polydiacetylenes (PDAs) from the bis-ethyl- and bis-n-propyl urethanes of 5,7-dodecadiyn-1,12-diol (ETCD and PUDO, respectively) and the nonthermochromic 1,6-bis-p-toluenesulfonate of 2,4-hexadiyne-1,6-diol (PTS) at temperatures above and below the thermochromic phase transition. PDA-PTS has an ionization energy of 5.66 eV which does not change significantly as the temperature is raised above 140 degrees C. At 25 degrees C, PDA-ETCD and PDA-PUDO have threshold ionization energies of 5.65 and 5.51 eV, respectively. The ionization energies of these PDAs increase by approximately 0.34 eV as temperature is raised above 140 degrees C and returns to the lower values as temperature is reduced to 25 degrees C. The magnitude of the increase in ionization energy on heating to temperatures above the thermochromic transition is very close to the shift in energy of the electronic spectrum over the same temperature range. These observations suggest that the structural changes that take place in the course of the thermochromic transition are primarily associated with the valence band and are consistent with partial relief of mechanical strains.

The Interaction of Vacuum Ultraviolet Light with Crystalline Monoacetylenes: A Progress Report

Abstract With an eye toward a study of crystalline monoacetylene solid state reactivity as an approach to crystallographically ordered polyacetylenes, the crystallographic and absorption and emission spectral characteristics of 10-undecynamide and the cyclohexylurethanes of 5-hexyn-1-o1 and 10-undecyn-1-o1 have been studied at ambient temperature. Spectral studies at short wavelengths were performed using vacuum ultraviolet radiation from the National Synchrotron Light Source. The compounds investigated are not thermally reactive at temperatures below their melting points and are effectively inert to 60Co gamma radiation at room temperature. The crystal structures of 10-undecynamide and the cyclohexylurethane of 5-hexyn-1-o1 have been solved, and both reveal contacts shorter than 3.70 A between acetylenic carbon atoms. For 10-undecynamide, excitation at all wavelengths between 120 and 300 nm leads to emission at wavelengths greater than 300 nm.