Geometry and Raman spectrum of isoindigo

Structure and Raman spectra of pyridyl substituted diketo-pyrrolo-pyrrole isomers and polymorphs

“…We have recently shown [9] on BPPB, that the comparison of the experimental Raman spectra with the theoretical ones obtained by quantum chemical calculations is a valuable tool for an investigation of intermolecular hydrogen bonding between CO and NH functional groups. The same methodology was successfully applied to isoindigo [10]. Thus, the aim of this paper is experimental study on polycrystalline samples of pyridyl substituted DPPs by Raman spectroscopy, to optimize the molecular geometry of isolated molecules by suitable density functional theory (DFT) method and to compare it with the data from X-ray diffraction where available [7,8,11], to compute the theoretical Raman spectra based on this geometry, to assign the experimental frequencies and finally to identify the key modes sensitive to either molecular or crystal (H-bond induced) asymmetry.…”

“…The latest value is even higher than for 2PyPP2Py, as predicted by theory for isolated molecule (Table 3). It was already shown [9,10], that NAH bending mode 13 a g (Fig. 10) near 1400 cm À1 is also very sensitive to H-bonding, which shifts its frequency to higher values.…”

“…Their agreement with the experimental ones thus depends among others on a similarity of computed and real geometry. DFT method with the most widely used B3LYP xc functional [18] and its combination with 6-311++G(d,p) basis set was successfully used in our previous studies [9,10]. Calculations for 4-pyridyl derivatives were straightforward and resulted in a strictly planar geometry for 4PyPP4Py and thus C 2h symmetry.…”

Novel isoindigo-based conjugated polyelectrolytes: Synthesis and fluorescence quenching behavior with water-soluble poly(p -phenylenevinylene)s

“…In the past few years, dye‐based conjugated polymers have attracted great attention and almost all of these polymers exhibit excellent photoelectric properties due to their large conjugated system . Isoindigo (ID) is a kind of indigoid dyes as same as indigo and isatin, in which two indolin‐2‐one units are connected by the central CC bond in E configuration and two intramolecular hydrogen bonds occur between CO and NH groups . Investigation of the medicinal properties of ID derivatives reveals that ID derivatives such as 1‐methylisoindigo (Meisoindigo) and 1‐(tri‐ O ‐acetylxylopyranosyl)‐isoindigo (Natura) have a great anticancer potency .…”