Spectral properties of new N,N'-bis-alkyl-1,4,6,8-naphthalenediimide complexes.

The photophysical properties of two N,N'-bis-alkyl-1,4,6,8-naphthalenediimide (DCN1 and DCN2) have been studied in chloroform and N,N-dimethylformamide solvents. The ability of DCN2 in N,N-dimethylformamide to detect metal cations have been monitored by the fluorescence emission spectroscopy. It has been shown that the fluorescent intensity is very sensitive to the concentration of Fe3+ cations. The reaction of iodine with N,N'-bis-alkyl-1,4,6,8-naphthalenediimide in chloroform solution have been investigated by spectrophotometric method. The results indicate the formation of two CT-complexes [(DCN1)I]+.I3- and [(DCN2)I]+.I3- at donor:acceptor molar ratio of 1:2. The [(DCN1)I]+.I3- shows the characteristic absorptions of I3- ion at 290 and 360 nm while the charge-transfer transition of [(DCN2)I]+.I3- occurs at 310 nm. Three characteristic bands at the far infrared region in each iodine complex are observed around 135, 105 and 85 cm-1 due to nuas (I-I), nus (I-I) and delta (I3-), respectively with C2v symmetry. The values of the complex formation constant, K, and the absorptivity, epsilon have been calculated.

Simultaneous Measurement of Fluorescence, Conversion and Physical/mechanical Properties for Monitoring Bulk and Localized Photopolymerization Reactions in Heterogeneous Systems.

An FT-NIR spectrometer, rheometer and fluorescence spectrophotometer were coupled for the real-time monitoring of polymerization reactions, allowing the simultaneous tracking of polymerization kinetics, storage modulus as well as fluorescence. In this study, a methacrylate functionalized dansyl chromophore (DANSMA) was synthesized and two different nanogels were made from urethane dimethacrylate and isobornyl methacrylate. Two series of resin formulations were prepared using the DANSMA probe, ethoxylated bisphenol A dimethacrylate as the matrix monomer, Irgacure® 651 as the initiator and the dispersed, monomer-swollen nanogels to give clear UV-curable resins. Placement of the fluorescent probe either throughout the resin or linked into the nanogel before its dispersion in the matrix provides a tool to study how the nanogel structure affects local network development by means of fluorescence from the DANSMA probe. We demonstrate the potential of this new technique using a composite as the two phase system (resin and polymerizable nanogel) including a dansyl derivative as a polymerizable probe to follow the reactions that are taking places in both phases.

Fluorescent dendrimers as sensors for biologically important metal cations.

The review presents fluorescence spectroscopic studies on the capacities of newly synthesized polypropyleneamine and polyamidoamine fluorescent dendrimers to detect biologically important metal ions. It has been shown that those fluorescent dendrimers whose periphery comprises 1,8-napthalimide fragments are highly sensitive to metal ions which are of great importance to the living organisms.