Basic info about Carbazole and ethyl carbazole

Anonymous
timer Asked: Jan 10th, 2019
account_balance_wallet $5

Question Description

I want you to find specific information about those two, I don’t want an essay or a report, just the information that I’ll request with the citation of cou

Tutor Answer

proggerardo
School: Rice University

Update. Data from carbazole (except MA)

Journal of Luminescence 93 (2001) 51–74

Electronic spectroscopy of carbazole and N- and C-substituted
carbazoles in homogeneous media and in solid matrix
Sergio M. Bonesi, Rosa Erra-Balsells*
Departamento de Quı´mica Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, c.c.74-suc. 30,
1430 Buenos Aires, Argentina
Received 3 August 1999; received in revised form 28 June 2000; accepted 15 November 2000

Abstract
The dynamic properties of the lowest excited singlet and triplet states in terms of fluorescence and phosphorescence
lifetime, tf and tp, fluorescence and phosphorescence quantum yield, ff and fp, for carbazole and N- and C-substituted
carbazoles have been measured in organic solutions of different polarity and in solid matrix, at 298 and at 77 K,
respectively. From these data, the radiative and the radiationless rate constants (k0f ; kisc ; k0f ð77Þ; kisc ð77Þ; k0p and k0nr )
and the intersystem crossing quantum yield, fisc, were easily derived. Electronic spectra (absorption, fluorescence and
phosphorescence emission spectra) of carbazole and carbazole derivatives have been recorded at 298 and at 77 K and
the solvent and substituent effects on the spectroscopic data and on the photophysical rate constant have also been
analyzed and good linear correlations have been obtained. The values of the HOMO and LUMO energy, the oscillator
strength ( f ), the transition dipole (Dm) and the wavelengths associated to the electronic transitions, the heat of
formation of the carbazoles and the corresponding radical cations (DHf and DHf (RC)) and the adiabatic ionization
potential (Ia) were calculated by using the semiempirical PM3 and ZINDO/S methods and were compared with the
spectroscopic and photophysical parameters obtained as well as with the one-electron oxidation potential data (Ep/2)
reported for the carbazole series. # 2001 Elsevier Science B.V. All rights reserved.
Keywords: Carbazoles; Electronic spectra at 298 K; Electronic spectra at 77 K; ZINDO/S carbazole electronic spectra calculations;
ZINDO/S carbazole molecular orbital calculations

1. Introduction
The electronic absorption spectra and photophysics of carbazole and some carbazole derivatives have been mainly studied by using
steady-state spectroscopic methods [1–16].
*Corresponding author. Tel.: +54-11-45763346; fax: +5411-45763346.
E-mail address: erra@qo.fcen.uba.ar (R. Erra-Balsells).

Quenching of the first electronic excited singlet
state of carbazole and some N-substituted derivatives by haloalkanes has also attracted the attention of several researchers, the quenching
mechanism being explained by an intermolecular
electron transfer process [10–17]. These electron
transfer interactions have also been invoked as a
primary step in the photochemical reactivity of
carbazole in the presence of CCl4 [18–25] and
CH2Cl2 [26–28].

0022-2313/01/$ - see front matter # 2001 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 2 3 1 3 ( 0 1 ) 0 0 1 7 3 - 9

52

S.M. Bonesi, R. Erra-Balsells / Journal of Luminescence 93 (2001) 51–74

Owing to their special photophysical properties,
polymers containing as pendant group the carbazolyl chromophore are good electron donors and
possess outstanding electrical and photoelectrical
properties [27–31].
Besides, in order to monitor the kinetics and the
extent of thermotropic and ionotropic lateral
phase separations in vesicles in the presence of
Ca2+, fluorescence studies using carbazole-labeled
and brominated phospholipids have been conducted [32]. These methods have been used to
measure the partition coefficient and diffusional
rate of chlorinated hydrocarbons in synthetic
phospholipid vesicles [33,34] and in cell membranes [34]; as application of the latter, bioaccumulation of synthetic chlorinated pesticides into
membranes has been estimated [35–38].
Thus, the study of the photochemical reactivity
(photostability) of carbazoles and of their photophysics including time-resolved fluorescence and

phosphorescence spectroscopy is essential to properly select carbazole derivatives in order to design
new organic polymers and new bio-organic photosensors.
As part of an on going program related to the
study of the photochemistry of azacarbazoles [39–
43] and carbazoles [44–46] we decided to study in
detail the electronic spectra of several carbazoles
whose photochemistry we are interested in. To
begin with we studied the absorption, fluorescence
and phosphorescence spectra of carbazole (1),
N-methyl- (2), N-phenyl- (3), N-vinyl- (4), Nacetyl- (5), N-benzoyl- (6), 2-methoxy-N-methyl- (7),
2-hydroxy- (8), 2-acetoxy- (9), 3-chloro- (10),
3-bromo- (11), 3-nitro- (12), 3,6-dibromo- (13),
3-benzoyl- (14), 3,6-dibenzoyl- (15), 3,6-dichloroN-benzoyl- (16) and 1-nitrocarbazole (17) (see
Scheme 1). These studies have been performed in
different organic solvents, under different atmospheres at 298 and 77 K by using time correlated

Scheme 1. Structure of the carbazoles studied.

S.M. Bonesi, R. Erra-Balsells / Journal of Luminescence 93 (2001) 51–74

single photon counting technique and phosphorescence lifetimes spectroscopy.
The dynamic properties of the lowest excited
singlet and triplet states in terms of fluorescence
and phosphorescence lifetime, tf and tp, fluorescence and phosphorescence quantum yield, ff and
fp, have been measured at 298 and at 77 K. From
these data, the radiative and the radiationless rate
constants (k0f ; kisc ; k0f ð77Þ; kisc ð77Þ; k0p and k0nr )
and the intersystem crossing quantum yield, fisc,
were derived. Also, the solvent and the substituent
effects on the different spectroscopical and photophysical parameters were analysed. The HOMO
and LUMO energies and the ionization potential
(Ia) of carbazoles were calculated (PM3 method)
and related to the one electron oxidation potential
(Ep/2) of each carbazole. Theoretical absorption
spectra have been calculated (ZINDO/S) and
compared with the experimental ones.

2. Experimental
2.1. Materials
Carbazole, N-methylcarbazole, N-phenylcarbazole, N-vinylcarbazole, 2-hydroxycarbazole and
3,6-dibromocarbazole were purchased from
Aldrich Chemicals Co. and were purified by repeated recrystallizations from appropriate solvents.
The other carbazole derivatives N-acetylcarbazole
[44], N-benzoylcarbazole [45–47], 2-methoxy-Nmethylcarbazole
[48,49],
2-acetoxycarbazole
[50,51] 1-nitrocarbazole [27], 3-nitrocarbazole
[27], 3-bromocarbazole [51,52], 3,6-dichloro-Nbenzoylcarbazole [49], 3-benzoylcarbazole [47], 3chlorocarbazole [51] and 3,6-dibenzoylcarbazole
[47] were synthesized according to literature
procedures.
Acetonitrile and cyclohexane (J.T. Baker Spectrograde), ethanol, iso-propanol, dichloromethane,
ethyl ether and ethyl acetate (Merck HPLC grade)
were used as purchased without any further
purification. Water of MiliQ grade, perchloric
acid and sulphuric acid of analytical grade were used.
Rhodamine B, quinine sulphate and p-terphenyl
(Aldrich Chemicals Co. and Sigma) were used as
purchased.

53

2.2. Equipment
The absorption measurements were performed
with a spectrophotometer Hewlett-Packard HP5.
The spectrofluorimeter employed in this study
was a Hitachi F-500. Steady-state spectra were
obtained on freshly prepared nitrogen-degassed
solutions (NS) in spectral grade solvents. Measurements of air-saturated solutions (AS) were
also conducted. The quantum yields at room
temperature were determined relative to the
quantum yield of quinine sulphate in HClO4
0.1 N (QS). Freshly prepared solutions of QS were
used as references by adjusting absorbance values
to 0.20–0.30 au (arbitrary units) at 312 nm, where
all compounds showed significant absorption. The
absorption of each compound in solution was
adjusted to equal that of the standard QS sample,
and the fluorescence emission steady-state spectrum was obtained between 300 and 450 nm.
Fluorescence emission spectra were integrated
and the quantum yields were determined by the
ratio of the integrated areas of the fluorescence
spectrum with those of the QS spectrum (ff=0.55)
[53,54].
The quantum yield of carbazole at intervals
between room temperature and 77 K was established relative to the room temperature quantum
yield with corrections for changes in solute
concentration, index of refraction, and absorptivity with temperature according to the procedure
described by Mantulin and Huber [55]; we
obtained a fluorescence quantum yield value for
carbazole similar to that reported by Huber et al.
[56]. The quantum yields of the substituted
carbazoles at 77 K were determined relative to
that of carbazole, (ff(77 K)), by comparing the
corresponding integrated fluorescence signals. At
these low temperatures, phosphorescence is observed, and a simple comparison of the integrated
areas under the fluorescence and phosphorescence
spectra yields the phosphorescence quantum efficiency (fp) according to the recommended procedure [53,55,57].
The fluorescence lifetimes were measured on the
same solutions used in the steady-state measurements, by the single photon counting technique.
The Edinburgh OB 900 nanosecond fluorescence

54

S.M. Bonesi, R. Erra-Balsells / Journal of Luminescence 93 (2001) 51–74

spectrometer employed uses a nanosecond flash
lamp filled with hydrogen (0.42 bar). The resulting
decay curves were analyzed by convoluting a single
exponential with the Lamp function. The statistical parameters for lifetime analysis are, on
average, w2=1.037 and the Durbin–Watson
parameter=1.824. The excitation and emission
wavelengths were set as lmax(abs) and lmax(fluo),
respectively, the values selected depending on the
compounds studied. Provision is made for temperature control of the samples from room
temperature to 77 K using a quartz dewar vessel
equipped with a special block sample compartment for round quartz cells (0.5 mm diameter). In
the Edinburgh OB 900 fluorometer the emission
and excitation slits are arranged in horizontal
display. Phosphorescence decay curves were determined with the Hitachi F-500 spectrofluorimeter by using the phosphorescence mode, at
77 K. The phosphorescence lifetimes were determined by fitting the phosphorescence decay curves
with a mono-exponential function using the Origin
3.5 program.
All spectra were corrected by measuring the
instrumental response on excitation side (rhodamine B) and on emission side (cell diffuser). The
integrated fluorescence spectra of a solution of pterphenyl [53] in cyclohexane with an absorbance
of 0.521 au at 276 nm was recorded in order
to check the instrumental response of the Hitachi
F-500 spectrofluorimeter after measuring the
fluorescence emission spectra of each compound
under study.
2.3. Theoretical calculations
The ground state geometries were optimized by
ab initio calculations (HF level; 3-21G basis set;
Gaussian 98W, [58]). Heat of formation of
carbazoles was calculated by using the semiempirical parametrized PM3 method as implemented in
the HyperChem Suite program [58]. The geometries of the radical cations were optimized using
the unrestricted Hartree–Fock (UHF) formalism.
The adiabatic ionization potentials (Ia) were
calculated as the difference in DHf of the radical
cation, calculated by using RHF formalism from
the optimized structures using the UHF formalism

and DHf of the neutral form with the optimized
geometry. Qualitative structure–activity relationships (QSAR) properties were calculated as
implemented in ChemPlus: Extensions for
Hyperchem Suite [58]. UV visible spectroscopic
transitions and the corresponding oscillator
strength ( f ) and transition dipole (Dm) were
calculated by using the ZINDO/S method as it is
parametrized in HyperChem Suite [58].

3. Results
The absorption and fluorescence emission spectra of carbazole and carbazole derivatives were
analyzed in non-polar and polar solvents at 298 K.
The absorption spectra were recorded in the 200–
800 nm region and generally three bands were
observed. The position and oscillator strength of
the bands ( f ) at 330 and 290 nm of the carbazole
derivatives were compared with those of carbazole
[59] and were assigned as 1Lb (1S1 1S0) and 1La
(1S2 1S0) electronic transitions, respectively.
Furthermore, the positions and oscillator strength
of 1La and 1Lb were also verified by quantum
chemical calculations (ZINDO/S) which are fairly
close to the experimental values. Besides, a more
accurate analysis of the oscillator strength of 1La
and 1Lb bands of carbazole derivatives with
respect to those of carbazole may give additional
information about the geometry as well as the
electronic characteristic of these compounds.
Table 1 shows the oscillator strength ( f ) and the
transition dipole (Dm) associated with the electronic transition bands, 1La and 1Lb, together with
the lmax of absorption (lmax(abs)) and lmax of
fluorescence emission (lmax(fluo)).
The substituent effect on the 0,0 electronic
transition energy (E0,0) was also analyzed. For
this analysis Eq. (1) was used
½E 0;0 ðXÞE 0;0 ðCAÞ=2:303RT ¼ rA s;

ð1Þ

where X is the substituted carbazole and CA is
carbazole. The rA value is defined as the absorption constant and s are the Hammett parameters
[60] (sl, sp and sm). Kosower et al. [61] had earlier
developed Eq. (1) and later, Reichardt et al. [62,63]
successfully used this correlation for the study of

Carbazoles

1
2
3
4
5
6
7
8
9
10
11
13
a

MeCN

EtOH

Cyclohexane

lmax
(abs)
(nm)

lmax
(fluo)
(nm)

f ðS1 S0 Þa

lmax
(abs)
(nm)

lmax
(fluo)
(nm)

f ðS1 S0 Þa

lmax
(abs)
(nm)

lmax
(fluo)
(nm)

f ðS1 S0 Þa

Dmb
(D)

f ðS1 S0 Þc

Dmc
(D)

lmax
(abs)c
(nm)

f ðS2 S0 Þc

Dmc
(D)

lmax
(abs)c
(nm)

334
346
340
340
314
314
336
318
332
344
346
350

355
366
360
362
329
355
358
345
353
356
357
361

0.071
0.059
0.050
0.041
0.010
0.007
0.040
0.048
0.059
0.057
0.057
0.091

338
344
340
340
312
314
332
320
332
346
346
350

358
363
358
360
329
356
356
347
355
357
357
360

0.076
0.073
0.162
0.186
0.007

0.117
0.134
0.190
0.055
0.064
0.013

332
344
340
340
310
316
334
314
330
340
340
348

347
360
356
357
328
347
353
339
355
354
355
351

0.077
0.067
0.118
0.093
0.015

0.082

0.059
0.061
0.031
0.018

5.63
5.36
3.81
5.30
6.06
12.06
4.71
6.26
5.88
5.02
5.04
5.90

0.009
0.028
0.082d
0.064
0.027
0.859
0.021
0.045
0.016




0.75
1.31
2.05d
1.99
1.27
7.25
1.13
1.65
0.97




281
293
290d
291
282
266
288
286
283




0.535
0.350
0.483d
0.363
0.542
0.618
0.555
0.576
0.754




5.54
4.50
5.26d
4.58
5.57
5.77
5.72
5.82
6.64




270
272
269d
271
269
253
277
277
275




Calculated according to f ðS1 S0 Þ ¼ 1:5k0f xn2 .
Dipole moment of the 1Lb transition derived from Lippert–Mataga relationship (see Eq. (2)).
c
Calculated using the semiempirical ZINDO/S method after HF/3-21G geometrical optimization.
d
N-phenyl substituent/carbazole moiety diedral angle ð f ðS1 S0 Þ, Dm, lmax(abs), f ðS2 S0 Þ, Dm, lmax(abs)), 548 (0.462, 5.15 D, 270 nm, 0.598, 5.82 D, 265 nm); 908 (0.809,
6.21 D, 268 nm).
b

S.M. Bonesi, R. Erra-Balsells / Journal of Luminescence 93 (2001) 51–74

Table 1
Spectroscopic data of carbazoles in different organic media at 298 K under inert atmosphere (N2) together with calculated spectroscopic data by ZINDO/S after
HF/3-21G geometrical optimization

55

56

S.M. Bonesi, R. Erra-Balsells / Journal of Luminescence 93 (2001) 51–74

the substituent effect on the E 0;0 of the betaine
chromophores. The results obtained in the present
work for carbazole and carbazole derivatives are
shown in Fig. 1.
Carbazole and carbazole derivatives exhibit
structured fluorescence spectra in different organic
media at 298 K with excitation into the S1 level.
The fluorescence and absorption spectra at room
temperature are found to display excellent mirror
symmetry with an exact overlap of the 0,0 bands
(Fig. 2). Also, these carbazoles show structured
fluorescence and phosphorescence spectra in isopropanol-ethyl ether (1 : 1; v : v) glass matrix at
77 K with electronic excitation into the S1 level
(Fig. 2). It is noteworthy to mention that there is
no noticeable change of lmax(fluo) on going from
298 to 77 K. Also, the C- and N-substitution
effects on lmax(fluo) at both temperatures show a
similar trend as it is observed when E 0;0 is
correlated to the Hammett parameters. All these
spectroscopic data of carbazoles are shown in
Tables 1 and 2.

Fig. 1. Hammett correlation between sI- values and the
modified transition energies of the 0,0 absorption band of
substituted carbazoles in acetonitrile at 298 K: (*) N-substituted carbazoles; (m) C-3 substituted carbazoles; (&) C-2
substituted carbazoles. Numbers are the carbazole derivatives
(see Scheme 1). Lines show the best linear regressions obtained
according to Eq. (1) (see text).

Fig. 2. Electronic absorption spectra and fluorescence and
phosphorescence emission spectra of carb...

flag Report DMCA
Review

Anonymous
Good stuff. Would use again.

Similar Questions
Hot Questions
Related Tags
Study Guides

Brown University





1271 Tutors

California Institute of Technology




2131 Tutors

Carnegie Mellon University




982 Tutors

Columbia University





1256 Tutors

Dartmouth University





2113 Tutors

Emory University





2279 Tutors

Harvard University





599 Tutors

Massachusetts Institute of Technology



2319 Tutors

New York University





1645 Tutors

Notre Dam University





1911 Tutors

Oklahoma University





2122 Tutors

Pennsylvania State University





932 Tutors

Princeton University





1211 Tutors

Stanford University





983 Tutors

University of California





1282 Tutors

Oxford University





123 Tutors

Yale University





2325 Tutors