On titration with CT-DNA, complex 1 exhibits slight hypochromic and narrow bathochromic
effects; whereas, complex 2 displays significant hypochromic and large bathochromic
effects; moreover, complex 3 shows slight hyperchromic and narrow hypsochromic effects.
Once the shifts means the appearing of stretching frequencies at lower energy values in the electromagnetic spectrum, these events are well known as red- shifts rather than the bathochromic
effect widely cited .
Meanwhile, larger bathochromic
shift was observed in fibers than in films, because the [pi] -[pi] interaction of electrospun membrane was stronger than that of coating film.
The maximum absorption wavelength was 725 nm, showing a bathochromic
shift with respect to the maximum absorption at 720 nm of free ligand (Fig.
Otherwise the conjugation length would be larger and a bathochromic
shift would be observed.
When diluted in distilled water (pH = 3.8) or in methanol (pH = 12), maximum absorption peaks can be observed in three bands: 243~243.5nm, 280~282nm, and 324~331nm, respectively, with a slight bathochromic
shift, but with a strong hypsochromic shift at a wavelength from 383.6 nm to 302.5 nm.
The absorption wavelengths of complexes (1)-(4) have shifted towards longer wavelengths (bathochromic
shift) compared to the wavelengths of the reactants (copper, ferrozine, and ferene).
Generally, the better conjugation in the thiophene-based analogue would cause some small bathochromic
shift of the band maximum, not only its broadening.
It can be seen as expected that there is a gradual systematic bathochromic
shift of the important MLCT transition as the electron affinity of the functional group located on the polypyridyl ligand is increased.
shifts of asymmetric ([v.sub.as]) and hypsochromic shifts of symmetric ([v.sub.s]) frequencies are also observed.
The absorption peaks of P2 observed at 514 nm and 560 nm reveal a bathochromic
shift when compared to the copolymer P1.
Increasing the pH above 6.0 causes a bathochromic
shift on the [pi]-[[pi].sup.*] transition bands, such transitions are associated to the imine bond with wavelengths between of 260-370 nm. This shift was also observed when the solvent was replaced by methanol (see Supporting information).