Excited-state mixed-valence distortions in a diisopropyl diphenyl hydrazine cation.

Excited-state mixed valence (ESMV) occurs in the 1,2-diphenyl-1,2-diisopropyl hydrazine radical cation, a molecule in which the ground state has a symmetrical charge distribution localized primarily on the hydrazine, but the phenyl to hydrazine charge-transfer excited state has two interchangeably equivalent phenyl groups that have different formal oxidation states. Electronic absorption and resonance Raman spectra are presented. The neighboring orbital model is employed to interpret the absorption spectrum and coupling.

Photoisomerization of azobenzene derivatives in nanostructured silica.

A series of derivatized azobenzene molecules are synthesized such that one of the phenyl groups can be chemically bonded to mesostructured silica and the other, derivatized with dendrons, is free to undergo large-amplitude light-driven motion. The silica frameworks on which the motion takes place are either 150 nm thick films containing ordered hexagonal arrays of tubes (inner diameter about 2 nm) containing the bonded azobenzenes, or particles (about 500 nm in diameter) containing the same ordered arrays of functionalized tubes. The photoisomerization yields and the rate constants for the thermal cis to trans back-reaction of the azobenzenes in the tubes are measured and compared to those of the molecules in solution.

The vault exterior shell is a dynamic structure that allows incorporation of vault-associated proteins into its interior.

Vaults are 13 million Da ribonucleoprotein particles with a highly conserved structure. Expression and assembly by multimerization of an estimated 96 copies of a single protein, termed the major vault protein (MVP), is sufficient to form the minimal structure and entire exterior shell of the barrel-shaped vault particle. Multiple copies of two additional proteins, VPARP and TEP1, and a small untranslated vault RNA are also associated with vaults.

Excited-state mixed valence in transition metal complexes.

Mixed valence in the lowest-energy metal-to-ligand charge-transfer excited state of di-(4-acetylpyridine)tetraammineruthenium(II) complexes is defined and analyzed. The excited state has two interchangeably equivalent ligands with different oxidation states. The electronic absorption band energies, selection rules, and bandwidths are analyzed quantitatively in terms of the signs and orientations of the transition dipole moments, sign and magnitude of the coupling, and resonance Raman analysis of displaced normal modes.

Formation of titanium nitride nanoparticles within mesoporous silica SBA-15.

We report the first synthesis of titanium nitride (TiN) nanoparticles inside the nanoscale channels of mesoporous silica SBA-15. The TiN precursor, Ti(NMe(2))(4) in toluene, was incorporated into the methyl group-modified channels of the SBA-15 powder. The functionalization of pore surfaces with methyl groups generates hydrophobic surfaces that facilitate impregnation with Ti(NMe(2))(4) and minimizes reactions between the TiN precursor and the hydroxyl groups on the surface of SBA-15.

Construction of a pH-driven supramolecular nanovalve.

[Structure: see text] The versatility of supramolecular chemistry has been exploited in constructing nanovalves based on mesoporous silica MCM-41 and the mutual recognition between secondary dialkylammonium ions and dibenzo[24]crown-8 (DB24C8). Naphthalene-containing dialkylammonium threads were tethered to the MCM-41, followed by loading with coumarin 460 and capping with DB24C8. Controlled release of coumarin 460 from the pores of MCM-41 was demonstrated using different bases.

Excited-state mixed valence in a diphenyl hydrazine cation: Spectroscopic consequences of coupling and transition dipole moment orientation.

A quantitative model of mixed-valence excited-state spectroscopy is developed and applied to 2,3-diphenyl-2,3-diazabicyclo[2.2.2]octane.

Wavelength dependent photofragmentation patterns of tris(2,2,6,6-tetramethyl-3,5-heptanedionato)Ln (III) (Ln = Eu, Tb, Gd) in a molecular beam.

Laser photoionization and ligand photodissociation in Ln(thd)(3) (Ln = Eu, Tb, Gd; thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) are studied in a molecular beam via time-of-flight mass spectrometry. The fragmentation patterns are strongly wavelength dependent. With 355 nm excitation, the mass spectrum is dominated by Ln(2+), Ln(+), and LnO(+) fragments.

Optical spectra of protected diamine 10-bond-bridged intervalence radical cations related to N,N,N'N'-tetraalkylbenzidine.

The optical absorption spectra of the delocalized intervalence radical cations of seven o,o'-linked benzidine derivatives that have the nitrogens protected as 9-(9-aza-bicyclo[3.3.1]nonan-3-one) derivatives are discussed and compared with that of the p-phenylene radical cation.

Photoinduced electron transfer in 2-tert-butyl-3-(anthracen-9-yl)-2,3-diazabicyclo[2.2.2]octane.

Intramolecular photoinduced electron transfer from a hydrazine unit to an aromatic group is studied by resonance Raman spectroscopy and electronic absorption spectroscopy. Substituted hydrazine functional groups have played an important role in studies of electron-transfer reactions, photoinduced intramolecular electron transfer, and of mixed valence. A prototypical compound, 2-tert-butyl-3-(anthracen-9-yl)-2,3-diazabicyclo[2.

A thalidomide analogue with in vitro antiproliferative, antimitotic, and microtubule-stabilizing activities.

We discovered a thalidomide analogue [5-hydroxy-(2,6-diisopropylphenyl)-1H-isoindole-1,3-dione (5HPP-33)] with antiproliferative activity against nine cancer cell lines in vitro. Flow cytometric analyses showed that the compound caused G2-M arrest, which occurred mainly at the mitotic phase. In addition, immunofluorescence microscopy and in vitro tubulin polymerization studies showed that 5HPP-33 has antimicrotubule activity with a paclitaxel-like mode of action.

Interpretation of unusual absorption bandwidths and resonance Raman intensities in excited state mixed valence.

Excited state mixed valence (ESMV) occurs in molecules in which the ground state has a symmetrical charge distribution but the excited state possesses two or more interchangeably equivalent sites that have different formal oxidation states. Although mixed valence excited states are relatively common in both organic and inorganic molecules, their properties have only recently been explored, primarily because their spectroscopic features are usually overlapped or obscured by other transitions in the molecule. The mixed valence excited state absorption bands of 2,3-di-p-anisyl-2,3-diazabicyclo[2.

Photochemical charge separation within aromatic hydrazines and the effect of excited-state intervalence in dihydrazines.

Photolysis into the longest wavelength absorption band of 2-tert-butyl-2,3-diazabicyclo[2.2.2]oct-3-yl hydrazine (Hy) substituted naphthalenes causes aryl group reduction electron transfer to give (+)Hy-Ar(-).

A photoactive molecular triad as a nanoscale power supply for a supramolecular machine.

A tetrathiafulvalene-porphyrin-fullerene (TTF-P-C(60)) molecular triad, which generates electrical current by harnessing light energy when self-assembled onto gold electrodes, has been developed. The triad, composed of three unique electroactive components, namely, 1) an electron-donating TTF unit, 2) a chromophoric porphyrin unit, and 3) an electron-accepting C(60) unit, has been synthesized in a modular fashion. A disulfide-based anchoring group was tagged to the TTF end of the molecule in order to allow its self-assembly on gold surfaces.

Optical spectra of delocalized dinitroaromatic radical anions revisited.

The optical spectra of nine dinitroaromatic radical anions (1,2- and 1,4-dinitrobenzene, 1,5- and 2,6-dinitro naphthalene, 4,4'-dinitrobiphenyl, 2,7-dinitro-9,9-dimethylfluorene, 2,6-dinitroanthracene, and 2,7- and 1,8-dinitrobiphenylene) in dimethylformamide are reported and analyzed. All have delocalized charge distribution, as demonstrated by the vibrational fine structure that is observed in their optical spectra: All show lowest energy absorption bands that correspond to an alpha-homo (highest occupied molecular orbital) to alpha-lumo (lowest unoccupied) transition, as shown by Koopmans-based UB3LYP calculation of the orbital separation of the neutral at the geometry of the radical anion. These single-point calculations are shown to be significantly more accurate for five of these compounds than the much more complex and expensive TD-DFT method.

A reversible molecular valve.

In everyday life, a macroscopic valve is a device with a movable control element that regulates the flow of gases or liquids by blocking and opening passageways. Construction of such a device on the nanoscale level requires (i) suitably proportioned movable control elements, (ii) a method for operating them on demand, and (iii) appropriately sized passageways. These three conditions can be fulfilled by attaching organic, mechanically interlocked, linear motor molecules that can be operated under chemical, electrical, or optical stimuli to stable inorganic porous frameworks (i.

Hypopyon uveitis associated with systemic lupus erythematosus and antiphospholipid antibody syndrome.

Purpose: To report a case of hypopyon uveitis associated with systemic lupus erythematosus and antiphospholipid antibody syndrome.

Methods: Interventional case report: a 49-year-old woman with a history of systemic lupus erythematosus and antiphospholipid antibody syndrome presented with sudden onset of pain, redness, photophobia, and decreased vision in the left eye. Examination revealed hypopyon uveitis and vaso-occlusive retinopathy.

Engineering of vault nanocapsules with enzymatic and fluorescent properties.

One of the central issues facing the emerging field of nanotechnology is cellular compatibility. Nanoparticles have been proposed for diagnostic and therapeutic applications, including drug delivery, gene therapy, biological sensors, and controlled catalysis. Viruses, liposomes, peptides, and synthetic and natural polymers have been engineered for these applications, yet significant limitations continue to prevent their use.

Multiply doped nanostructured silicate sol-gel thin films: spatial segregation of dopants, energy transfer, and distance measurements.

Physical and chemical strategies that place designed molecules in spatially separated regions of surfactant-templated mesostructured silicate thin films are used to prepare films containing rhodamine 6G (R6G), lanthanide complexes, and both simultaneously. Fluorescence and photoexcitation spectra of R6G in amorphous and structured thin films show that it is located inside the surfactant micelles of structured thin films. A silylated ligand that binds lanthanides condenses to form part of the silica framework and causes the lanthanide to localize in the silica.

Nanostructured systems for biological materials.

The sol-gel process is a chemical technique for immobilizing biomolecules in an inorganic, transparent matrix. The dopant biomolecules reside in an interconnected mesoporous network and become part of the nanostructured architecture of the entire material. In this chapter, we review the sol-gel immobilization approach and discuss how it leads to the stabilization of a number of proteins against aggressive chemical and thermal environments.

Clostridium sordellii endophthalmitis after suture removal from a corneal transplant.

Purpose: To report a case of endophthalmitis caused by Clostridium sordellii.

Methods: A 33-year-old man sustained a penetrating injury of the right eye that resulted in several ocular surgical procedures including pars plana vitrectomy, scleral buckling, scleral-sutured posterior chamber intraocular lens, and penetrating keratoplasty. More than 4 years after the penetrating injury he presented for examination with pain, photophobia, redness, decreased vision, and floaters in the right eye.

Electrical or photocontrol of the rotary motion of a metallacarborane.

Rotary motion around a molecular axis has been controlled by simple electron transfer processes and by photoexcitation. The basis of the motion is intramolecular rotation of a carborane cage ligand (7,8-dicarbollide) around a nickel axle. The Ni(III) metallacarborane structure is a transoid sandwich with two pairs of carbon vertices reflected through a center of symmetry, but that of the Ni(IV) species is cisoid.

An operational supramolecular nanovalve.

A functioning nanomachine in the form of a supramolecular nanovalve that opens and closes the orifices to molecular-sized pores and releases a small number of molecules on demand is reported. The nanovalve, which is used to open and close the nanocontainer, is a pseudorotaxane composed of two components-a long thread containing a 1,5-dioxnaphthalene donor unit, which is attached to the solid support, and the moving part, the tetracationic cyclophane acceptor/receptor, cyclobis(paraquat-p-phenylene), which controls access to the interior of the nanopore. The nanocontainer is made out of mesoporous silica by using a dip-coating method.

Association between lower optic nerve laser Doppler blood volume measurements and glaucomatous visual field progression.

Aim: To perform a preliminary assessment of the relation between optic nerve circulatory parameters and glaucomatous visual field progression.

Methods: This study included 29 eyes of 23 patients with open angle glaucoma that had typical glaucomatous nerve fibre bundle visual field defects and increased cup to disc ratios. Laser Doppler flowmetry (Oculix) was used to measure relative optic nerve blood volume (Vol), velocity (Vel) and flow in the superior temporal (ST) and inferior temporal (IT) neuroretinal rim of the optic nerve.

Spectroscopic consequences of a mixed valence excited state: quantitative treatment of a dihydrazine diradical dication.

A model for the quantitative treatment of molecular systems possessing mixed valence excited states is introduced and used to explain observed spectroscopic consequences. The specific example studied in this paper is 1,4-bis(2-tert-butyl-2,3-diazabicyclo[2.2.