“…Figure exhibits UV−visible spectra of PAE-Fc-4 and -5, and UV−visible data for the polymers are given in Table . As shown in Figure , they show a peak at about 450 nm assignable to a d−d transition in the ferrocene unit; − ferrocene itself gives the d−d transition peak at 438 nm and di-Etnyl-Fc shows the d−d transition band at 451 nm (Table , run 7). In addition to the d−d transition peak, they show a stronger (ε = about 1.5 × 10 4 M -1 cm -1 ; molarity is based on the repeating unit) absorption peak assigned to a π−π* transition at about 330 nm. 2 UV−visible spectra of (a) PAE-Fc-4 and (b) PAE-Fc-5 in CHCl 3 .…”
Section: Resultsmentioning
confidence: 98%
“…They have various interesting electronic and optical properties. For example, they form charge transfer complexes, generate mixed valent states by oxidation, and show nonlinear optical properties − …”
Palladium-catalyzed polycondensation between diiodoferrocenes
(1,1‘-diiodoferrocene and
1,6-diiodo-1‘,6‘-biferrocene) and diethynyl aromatic compounds
HC⋮CArC⋮CH (e.g., 2,5-diethynylpyridine and 2,5-diethynyl-3-hexylthiophene) gives
poly(aryleneethynylene) (PAE) type polymers containing the ferrocene unit in the π-conjugated main chain. The
prepared polymers include
(FcC⋮CPhC⋮C)
n
, PAE-Fc-1,
(FcC⋮CPyC⋮C)
n
, PAE-Fc-2, and
(FcC⋮ChexThC
⋮C)
n
, PAE-Fc-3 (Fc = 1,1‘-ferrocenylene;
Ph = p-phenylene; Py = pyridine-2,5-diyl; hexTh
=
3-hexylthiophene-2,5-diyl). 1H-NMR and IR spectra of
the polymers are reasonable for their structures.
The PAE type polymer containing the pyridine unit (PAE-Fc-2) is
soluble in formic acid, and the polymer
containing the hexylthiophene unit (PAE-Fc-3) is soluble in common
organic solvents such as CHCl3,
THF, and benzene. UV−visible spectra of the polymers exhibit a
main π−π* absorption peak at about
330 nm and a d−d absorption peak at about 450 nm. The cyclic
voltammogram of the polymers in a
CH3CN/CH2Cl2 solution
shows a reversible Fe(II) ⇄ Fe(III) redox cycle at about
0.25 V vs Ag/Ag+, and
the redox peaks are broadened compared with those of
low-molecular-weight ferrocenes. Exchange of
electrons along the main chain is considered to be the origin of the
broadening. The polymers themselves
are insulating, however, they are converted into semiconducting
materials with conductivity of 10-7 to
10-4 S cm-1 by formation of adducts with
iodine. Mössbauer spectra of the polymers reveal oxidation
of
Fe(II) in the ferrocene unit of PAE-Fc-1 to Fe(III), and the
ease of the oxidation reflects the electronic
properties of the polymer.
“…Figure exhibits UV−visible spectra of PAE-Fc-4 and -5, and UV−visible data for the polymers are given in Table . As shown in Figure , they show a peak at about 450 nm assignable to a d−d transition in the ferrocene unit; − ferrocene itself gives the d−d transition peak at 438 nm and di-Etnyl-Fc shows the d−d transition band at 451 nm (Table , run 7). In addition to the d−d transition peak, they show a stronger (ε = about 1.5 × 10 4 M -1 cm -1 ; molarity is based on the repeating unit) absorption peak assigned to a π−π* transition at about 330 nm. 2 UV−visible spectra of (a) PAE-Fc-4 and (b) PAE-Fc-5 in CHCl 3 .…”
Section: Resultsmentioning
confidence: 98%
“…They have various interesting electronic and optical properties. For example, they form charge transfer complexes, generate mixed valent states by oxidation, and show nonlinear optical properties − …”
Palladium-catalyzed polycondensation between diiodoferrocenes
(1,1‘-diiodoferrocene and
1,6-diiodo-1‘,6‘-biferrocene) and diethynyl aromatic compounds
HC⋮CArC⋮CH (e.g., 2,5-diethynylpyridine and 2,5-diethynyl-3-hexylthiophene) gives
poly(aryleneethynylene) (PAE) type polymers containing the ferrocene unit in the π-conjugated main chain. The
prepared polymers include
(FcC⋮CPhC⋮C)
n
, PAE-Fc-1,
(FcC⋮CPyC⋮C)
n
, PAE-Fc-2, and
(FcC⋮ChexThC
⋮C)
n
, PAE-Fc-3 (Fc = 1,1‘-ferrocenylene;
Ph = p-phenylene; Py = pyridine-2,5-diyl; hexTh
=
3-hexylthiophene-2,5-diyl). 1H-NMR and IR spectra of
the polymers are reasonable for their structures.
The PAE type polymer containing the pyridine unit (PAE-Fc-2) is
soluble in formic acid, and the polymer
containing the hexylthiophene unit (PAE-Fc-3) is soluble in common
organic solvents such as CHCl3,
THF, and benzene. UV−visible spectra of the polymers exhibit a
main π−π* absorption peak at about
330 nm and a d−d absorption peak at about 450 nm. The cyclic
voltammogram of the polymers in a
CH3CN/CH2Cl2 solution
shows a reversible Fe(II) ⇄ Fe(III) redox cycle at about
0.25 V vs Ag/Ag+, and
the redox peaks are broadened compared with those of
low-molecular-weight ferrocenes. Exchange of
electrons along the main chain is considered to be the origin of the
broadening. The polymers themselves
are insulating, however, they are converted into semiconducting
materials with conductivity of 10-7 to
10-4 S cm-1 by formation of adducts with
iodine. Mössbauer spectra of the polymers reveal oxidation
of
Fe(II) in the ferrocene unit of PAE-Fc-1 to Fe(III), and the
ease of the oxidation reflects the electronic
properties of the polymer.
“…Although metal binding to the center ring of coronene generates a structure with a pleasing symmetry, previous theoretical work 57,58 indicates that the outer rings of coronene are the favored locations for metal binding, and indeed complexes with such structures ͑e.g., cyclopentadienyl-iron-coronene͒ have been synthesized. [59][60][61] Among the structures we reported here, none has the metal atom or dimer binding to the center ring of the coronene, including the sandwich structures. The iron atom binds to the bridge site of coronene in Fe 1 ͑coronene͒ 1 , which is different from Ti 1 -, V 1 -, and Co 1 ͑coronene͒ 1 systems.…”
Fe(m)(coronene)(n) (m=1,2, n=1,2) cluster anions were generated by a laser vaporization source and studied by anion photoelectron spectroscopy. Density functional theory was used to calculate the structures and the spin multiplicities of those clusters as well as the electron affinities and photodetachment transitions. The calculated magnetic moments of Fe(1)(coronene)(1) and Fe(2)(coronene)(1) clusters suggest that coronene could be a suitable template on which to deposit small iron clusters and that these in turn might form the basis of an iron cluster-based magnetic material. Fe(1)(coronene)(2) and Fe(2)(coronene)(2) cluster anions and their corresponding neutrals prefer the sandwich-type structures, and the ground state structures of these clusters are all staggered sandwiches.
“…[10a, 11,25] For compounds 4 and 6, the two characteristic CT bands exhibit bathochromic shifts when the solvent polarity is increased, thus indicating increased polarity in the excited state. The solvatochromism is much larger for 4 than for 6, whereas the solvent influence is negligible for compound 5.…”
Section: Linear and Nonlinear Optical Propertiesmentioning
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