ABSTRACT
Two photochromic spirodihydroindolizine/betaine systems for tethering to peptides and proteins via a maleimide function have been prepared. The absorption spectra of the betaines are in the red region of the visible spectrum and in the near-IR spectral domain, which are suitable energies of light for future in vivo applications. The half-times of cyclization have been determined for both DHI/betaine systems. The findings are consistent with a thermal barrier of varying size between the transoid and cisoid conformers of the betaines.
Subject(s)
Betaine/chemistry , Indolizines/chemistry , Maleimides/chemistry , Spiro Compounds/chemistry , Molecular Structure , Photochemistry , Spectroscopy, Near-InfraredABSTRACT
We have synthesized a prototype of a photochromic styrylquinolyl-dihydroindolizine (DHI), which forms a highly coloured and fluorescent betaine upon irradiation with lambda<400 nm. Embedding this photochromic DHI in a thin polymethyl methacrylate (PMMA) film permits the non-destructive readout via fluorescence at low temperature (77 K). Thus, either a non-destructive photoswitch or an information recording system becomes available. Both possibilities have been explored: image recording and read-out, as well as information storage (at 77 K) have been demonstrated. Cluster- and single molecule-fluorescence upon laser excitation (lambda=355 nm) of the styrylquinolyl-dihydroindolizine in a PMMA matrix, and the effect of fluorescence blinking has been observed.
ABSTRACT
A novel Ru(II) complex possessing two sequentially linked viologen units, Ru-V(1)-V(2)(6+), was synthesized and characterized. Upon excitation of the Ru(II) unit (lambda(exc) = 532 nm, fwhm approximately 10 ns), a long-lived charge-separated (CS) state is observed (tau = 1.7 micros) by transient absorption spectroscopy. Unlike Ru(bpy)(3)(2+), which cleaves DNA upon photolysis through the formation of reactive oxygen species, such as (1)O(2) and O(2)(-), the photocleavage of plasmid DNA by Ru-V(1)-V(2)(6+) is observed both in air and under N(2) atmosphere (lambda(irr) > 395 nm).
Subject(s)
DNA Damage , DNA/chemistry , Organometallic Compounds/chemical synthesis , Ruthenium/chemistry , Viologens/chemistry , DNA Damage/drug effects , DNA Damage/radiation effects , Electrophoresis, Agar Gel , Molecular Structure , Nitrogen/chemistry , Organometallic Compounds/chemistry , Oxidation-Reduction , Photochemistry , PlasmidsABSTRACT
New molecules incorporating a uracil nucleic base and a dihydroindolizine (DHI) unit linked via spacer arms, i.e., uracil-spyrodihydroindolizine (4), were synthesised as models for light sensitive systems for nucleic acid labelling. The uracil-DHI (4) undergoes easy photocoloration to the uracil-betaine (5) generating the UV-detectable species. Preliminary results show rather weak binding of uracil-DHI (4) to calf thymus-DNA.
