Luminescence of W(CO)₄(4-Me-phen) in Photosensitive Thin Films:  A Molecular Probe of Acrylate Polymerization

Abstract

The complex W(CO)4(4-Me-phen) (4-Me-phen = 4-methyl-1,10-phenanthroline) has been determined to be luminescent and act as a spectroscopic probe in UV-curable trimethylolpropane triacrylate/poly(methyl methacrylate) thin films. Electronic absorption and luminescence characteristics have been measured for this complex in room-temperature solutions and low-temperature (80 K) glasses and in 10 mil thin films of the unexposed and exposed acrylate resins. In each environment dual luminescence bands were observed which are attributed to triplet-centered metal-to-ligand charge-transfer (3MLCT) excited states. For the unexposed photoresist these transitions were recorded at 520 and 750 nm and in the exposed material these are moved to 525 and 715 nm, respectively. The lowest energy emission band undergoes a substantial blue-shift and intensifies greatly on polymerization; this phenomenon provides a useful molecular probe of the acrylate cross-linking process. These changes in emission characteristics are associated with a rigidochromic effect imparted on the lowest lying and solvent sensitive b2 → b2(π*) 3MLCT electronically excited state in this complex. The complex W(CO)5(4-CN-py) (4-CN-py = 4-cyanopyridine) was also investigated as a spectroscopic probe in the acrylate system but appears unsuitable for this purpose as it was found to degrade significantly in the resin.

In situ preparation and luminescent properties of LaPO4:Ce3+, Tb3+ nanoparticles and transparent LaPO4:Ce3+, Tb3+/PMMA nanocomposite

“…Moreover, since PMMA is non-toxic, it could be also useful in dentures, medicine dispensers, food handling equipments, throat lamps and lenses. PMMA embedding inorganic or organically modified inorganic particles has been cast into films to yield enhanced functional properties such as electrical conductivity, photoconductivity, photoinduced charge-transfer, nonlinear optical properties, photoluminescence [13,14,16,[19][20][21][22][23][24], mechanical [17,[25][26][27][28][29] and magnetic properties [30]. LaPO 4 :Ce 3+ , Tb 3+ is mainly used as a green emitting phosphor for fluorescent lamp due to its high quantum efficiency, thermal stability at high temperature and sharp emission around 543 nm with high intensity [31].…”

Dual‐emissive polydiphenylsilane nanocomposite: effect of N,N′‐bis(4‐hydroxysalicylidene)‐1,2‐phenylenediamine‐Zn complex

“…A high PL intensity has resulted at the excitation of λ exc = 247 nm, giving a strong maxima at 310 nm with a low shoulder at 370 nm. This kind of emission profile showing two emission bands for a single excitation wavelength is known as “dual emission.” The cause relies in a dipole–dipole coupling of the metal coordinated (hydroxysalicylidene)amine with phenylene as the donor and acceptor parts, respectively, of the MC molecule. Thus, the energy of the donor in the excited state is transferred to the acceptor through the so‐called florescence resonance energy transfer.…”

“…This kind of emission profile showing two emission bands for a single excitation wavelength is known as "dual emission." [41,42] The cause relies in a dipole-dipole coupling of the metal coordinated (hydroxysalicylidene)amine with phenylene as the donor and acceptor parts, respectively, of the MC molecule.…”

Structural and optical properties of polymer composites/porous silicon

“…The efficiency of LEDs has been found to improve using a PS p-n junction. Efficient electroluminescence of lightemitting diodes with a PS p-n junction has been obtained by increasing electron and hole injection into the emitting region through the incorporation of a p-n junction [2]. Semi-transparent metal layer, Indium Tin Oxide and conducting polymers are some important contact materials used for forming PS p-n junction [3].…”