Photopolymerizable organically modified holographic glass with enhanced thickness for spectral filters

A novel formulation and synthesis method to overcome the thickness limitations in samples of photopolymerizable glasses with high refractive index species is presented. The reported method allows the recording of volume holographic diffraction gratings in samples of similar to 500 mu m thickness with a high optical quality and low scattering. Holographic grating recording is performed in a single coherent light exposure step, resulting in volume gratings of high optical quality. A holographic notch filter implemented in a 500 mu m thick photopolymerizable glass with a spectral bandwidth below 0.3 nm and an excellent filter extinction ratio of <-27 dB is also demonstrated

Amino-acrylamido carbenes : modulating carbene reactivity via decoration with an α,β-unsaturated carbonyl moiety

Two 6-methoxy-4-oxo-1,3-diaryl-3,4-dihydropyrimidinium salts (2a and 2b) have been prepared as precursors to novel amino-acrylamido carbenes. Treatment of 2a (where the aryl groups are mesityl groups) with one equivalent of sodium hexamethyldisilazide in aromatic hydrocarbons affords the persistent amino-acrylamido carbene 3a, which has been characterized spectroscopically. This novel carbene has been trapped with Ir(I) transition metal fragments as well as electrophilic carbon disulfide and nucleophilic isocyanides. Infrared spectroscopic studies carried out on 3a-Ir(CO)2Cl (5a) indicated that this carbene exhibits a Tolman electronic parameter (TEP) of 2049 cm–1, a value that suggests that 3a is a stronger donor than both diamidocarbenes (DACs) and a recently reported amino-ureido carbene (DAC TEPs ≈ 2057 cm–1; amino-ureido TEP = 2058 cm–1), but similar σ-donating properties to a monoamido-amino carbene (TEP = 2050 cm–1). This result has been corroborated by DFT analyses carried out on all four species, which indicated that the HOMO and LUMO energies of 3a are comparable to the amino-ureido and monoamido-amino carbenes, whereas the DAC was shown to be more electrophilic with a much lower energy LUMO than the other three carbenes. Surprisingly, deprotonation of 2b (where the N-substituents are 2,6-diisopropylphenyl groups) does not afford the anticipated carbene. Indeed, 1H NMR spectroscopic analysis indicates the formation of a novel bent allene or carbodicarbene (3b), which decomposes rapidly in solution at room temperature