Raman Spectra of Poly(p‐phenylenevinylene)s with Fluorinated Vinylene Units: Evidence of Inter‐ring Distortion

Abstract

Ring the changes: Experimental Raman spectra of fluorinated and non-fluorinated polyphenylenevinylenes are assigned according to quantum chemical calculations for oligomer model systems [picture: see text]. Characteristic differences in the spectra can be traced back to strong inter-ring distortion of the fluorinated compounds.The Raman spectrum of poly{2-methoxy-5-[(2-ethylhexyl)oxy]-1,4-phenylenedifluorovinylene} (MEH-PPDFV) is reported and compared with that of a well-known non-fluorinated reference polymer, namely poly{2-methoxy-5-[(2-ethylhexyl)oxy]-1,4-phenylenevinylene} (MEH-PPV). The Raman spectra of both polymers are assigned on the basis of density functional theory calculations of the corresponding oligomers. The main differences between vinylene fluorinated and non-fluorinated structures deal with the intensity, frequency shift and broadening of C--C vinylene stretching. Additional differences concern the relative intensities of C-C phenylene and vinylene stretching as well as the deformation modes in the range 1250-1350 cm(-1). It is shown that these effects are due to the larger distortion from planarity of the fluorinated polymer, compared with the non-fluorinated counterpart, induced by repulsive interactions between the fluorine atoms on the vinylene units and the oxygen atoms of the alkoxy groups on the aromatic rings.

Heterobinuclear Light Absorber Coupled to Molecular Wire for Charge Transport across Ultrathin Silica Membrane for Artificial Photosynthesis

“…This allowed more accurate assessment of any structural changes of the molecular wire upon anchoring and after casting into silica. In agreement with the FT-IR result, of the five Raman modes of PV3 solid powder observed in the 1200 -1700 cm -1 region at 1175, 1190, 1558, 1591, and 1631 cm -1 , [23][24][25][26][27] all but the 1591 cm -1 aryl stretch mode remain at the same frequency upon anchoring on silica and subsequent casting into a silica nanolayer. This observation confirms that the structure of the wire molecule, in particular the all-trans configuration of the aryl moieties is not significantly influenced by anchoring and silica embedding.…”

“…[ [23][24][25][26][27] The modes of anchored PV3 are more clearly seen after subtraction of the bands of unreacted TMSA anchors, as shown in Figure 1B, red trace (a), which was guided by the cancellation of the 1626 cm -1 NH 2 bend absorption of unlinked TMSA. Infrared spectra recorded after casting of the wires into 2 nm of silica remain unchanged (Figure 1 A, blue trace (c) and 1B, blue trace (b), the latter after subtracting unlinked TMSA bands), indicating structural integrity of the wire PV3 molecules despite the harsh (alkaline) conditions of the casting process.…”

Synthetic Aspects and Electro-Optical Properties of Fluorinated Arylenevinylenes for Luminescence and Photovoltaics

“…The theoretical predictions were experimentally confirmed by the Raman spectroscopy measurements [100]. …”

Copy number gains in EGFR and copy number losses in PTEN are common events in osteosarcoma tumors

“…We have recently contributed synthetic methodologies for several classes of fluorinated compounds11, 18, 19 for photonics and electronics, including PPV oligomers,20 and polymers selectively fluorinated on the aromatic rings21, 22–24 or on the vinylene units 25–28. In particular, poly( 2,3,5,6 ‐tetrafluorophenylenevinylene) (PTFPV)21 and random copolymers with dialkoxyphenylene‐vinylene and tetrafluorophenylene‐vinylene units22–24 have been synthesized via organometallic protocols based on the Stille cross‐coupling reaction of 1,4‐diiodotetrafluorobenzene, and eventually diiododialkoxybenzene, with ( E )‐1,2‐bis (tributylstannyl)ethylene, under Pd(0) catalysis.…”

“…The PTFPV polymer was used as the emitting layer in an OLED device obtaining blue‐green light emission. More recently, the Stille reaction polymerization was extended to the preparation of PPVs containing fluorinated vinylene units,25–28 starting from diiodoaryl derivatives and ( E )‐(1,2‐difluoro‐1,2‐ethenediyl)bis [tributylstannane] 25, 29. Interesting marks were obtained regarding the average molecular weights of polymers, which resulted in higher value compared to those of other typical Stille‐based polymerizations.…”