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The porphyrin handbook - Kadish K.M.

Kadish K.M. The porphyrin handbook - Academic press, 2000. - 368 p.
Download (direct link): kadishsmishgulilard2000.djvu
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Quartz
Figure 26. Effects of environment on second-order NLO behavior
10 -----------------------.
Organic Crystals
ii i
10
10
10
Poled
Polymers
Inorganic
Crystals
41 / Porphyrin Materials Chemistry
55
Mean Molecular Aien (A"-irolecu!e)
Figure 27. Langmuir-Blodgett isotherms or amphipliilk denvative.s of
"push-pull" porphyrins.
long chain fatty acid to the lice phenylamine functionalities, 'l'hc mean
molecular area of these LB iilms depended strongly on the number of alkyl
chains, as show n in the LB isotherms (Figure 27). The number of alkyl
chains did not change ihe porphyrin orientation, hut rather altered the
packing density of the porphyrins.
.Sen cl measured />' \allies of a series of donor-
aeceptor-subsliiuied fluoroar\ Ipoi phyrins hy using hyper-Rayleigh
scattering (HRS) al 1064 nm (Table 4). The first hyperpolarizabilities
are influenced by the nature and position of donor and acceptor groups.
An increase in /> values was observed when a //-pyrrole position of die
TPP chromophores was substituted with an electron-accepting nitro group.
The open-shell Cu(II) (d') porphyrins show larger />' values than do
closed-shell Zndl) (d porphyrins. The high observed /> values m /.n(ll)
porphyrins arc due to the large change in dipole moment upon excitation.
The highest /> values were obtained for porphyrins having N,N '-
diinelhylainino and nitro substituents. These porphyrins absorb at 532 mm
two-photon resonance enhancement contributes to large j> values but the
effect of metal d-electrons is more pronounced.
Priyadarshy et al. L calculated the first liyperpolarr/abil-ities of
porphyrin-bridged donor'-acceptor molecules using semi-empirical
INDO/SC1-SOS method. The chemical structures and calculated />' values
are shown in Table 5. The />' values of 5-((4'-
dimelhylamiiiophenyl)elhynyl)-15-((4"-nitrophenyi )ethvnvl)-10,20-
cliphenylporphyrinatozm-c(ll) |D-7.n(l)PP)-A| (4) calculated al '<S3()
and lOd-lnni were 8152 * 10 and 477 ' 10 "cm'/osu. respec-
tively. From such calculations, it is clear that resonant enhancements of
hyperpolarizabilities can he extremely important. This makes comparison
between experiments difficult unless the wavelengths used are far removed
Irom the intense porphyrin absorbance hands. The calculated pjl value at
1407 nm was 2548 10 4scm7esu. The hist
hyperpolarizabilities are one order of magniiude larger than other
porphyrin-bridged donor acceptor molecules. The diniethylainino-donor-
nitro-acceptor zinc species was determined to have a /> value four times
greater than that of a similar compound lacking the nitro-acceptor
substituent. This indicates that extended -conjugation length and
Table 4. Structure and First Hyperpolarizability of Sen's /(-Pyrrole
Substituted "Push-Pull" Fluoroarylporphyrins

\
f 1
! I-
I' I " I ' : f I
- \ " \ \ -
^ , ' : v
' i ' " >' v i '
i i
\
X Y M '| r.is
(10 10 esu)
F il 211 1>0
(Calc. 1.20)
N(CIf). II 7.20
(C'alc. 3.20)
F NO. 211 10.1
(Calc. 4.60)
NrC'tlj. NO- 211 54.0
(Calc. 32.0)
F II / 2.SO
NiCH,) - II 7 1 1.2
F NO, / 1 1 S
Nldls) no" / '>2.0
F H (' }.<)
Nl( '11. 11 ( ).2
i- NO (' I1) 6
Ni('If)_. NO. (' 1 18
SilLllcr Sell. V . R,.\ PC- lx,s. I* , 1 ishiutn. V 1 1 I1 In
('hem 1996. IOII.
1 1 : Sen. V Kii'.lin.in. V / ( : III Si , / ill Ilihl\ /-,
1997. 21
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