Chemiluminescence in the reaction of LnI2 (Ln = Dy, Nd) with water

Article abstract of DOI:10.1007/s11172-007-0304-9

Chemiluminescence (CL) upon the reaction of crystalline LnI₂ (Ln = Dy, Nd) with water was found. The CL emitters are the Ln^3+* electron-excited ions (Dy^3+*, λ_max = 470, 570 nm; Nd^3+*, λ = 700-1200 nm)

Full text of DOI:10.1007/s11172-007-0304-9

1
956
Russian Chemical Bulletin, International Edition, Vol. 56, No. 10, pp. 1956—1959, October, 2007
Chemiluminescence in the reaction of LnI (Ln = Dy, Nd) with water
2
R. G. Bulgakov,aꢀ S. P. Kuleshov, Z. S. Kinzyabaeva, A. A. Fagin, I. R. Masalimov, and M. N. Bochkarev
a
a
b
a
b
aInstitute of Petroleum Chemistry and Catalysis, Russian Academy of Sciences,
1
41 prosp. Oktyabrya, 450075 Ufa, Russian Federation.
Fax: +7 (347 2) 31 2750. Eꢀmail: ink@anrb.ru
b
G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
4
9 ul. Tropinina, 603950 Nizhnii Novgorod, Russian Federation.
Fax: +7 (831 2) 62 7497. Eꢀmail: mboch@iomc.ras.ru
Сhemiluminescence (CL) upon the reaction of crystalline LnI (Ln = Dy, Nd) with water
2
3
+
3+
was found. The CL emitters are the Ln * electronꢀexcited ions (Dy *, λ
Nd *, λ = 700—1200 nm) generated by the electron transfer from the Ln ions to the H O
= 470, 570 nm;
max
II
3
+
2
molecules. The identified reaction products are H , dissolved LnI , and insoluble LnI(OH)
2
3
2
(
49—51% and 48—50% yield for DyI and NdI , respectively). The treatment of NdI with an
2 2 2
H O solution in THF gives the NdI OH(thf) •3H O complex and hydrogen.
2
2
2
2
Key words: dysprosium, neodymium, diiodides, chemiluminescence, hydrolysis, photoluꢀ
minescence.
II
Chemiluminescence (CL) involving Ln compounds,
For recording IR spectra, the samples were prepared as a
suspension in Nujol and placed between NaCl plates. Photoluꢀ
minescence (PL) spectra were recorded on a homeꢀmade
spectrofluorimeter designed on the basis of an MDRꢀ23 double
monochromator. Absorption spectra were measured on Specord
Mꢀ40 (UVꢀvisible region) and Specord Mꢀ40 (IR region) specꢀ
trophotometers.
unlike LnIII compounds, was studied to less extent. The
CL is known for the EuCl complexes with organic
2
ligands1
—3
4
and Cp Yb, Cp Sm, and Cp Eu lanthanidoꢀ
2 2 2
cenes (see Refs 5 and 6) upon oxidation with hydrogen
peroxide and molecular oxygen. In all cases, the CL emitꢀ
3
+
3+
3+
3+
ters are the excited Ln * ions: Eu *, Yb *, and Sm *.
Chemiluminescence measurements. To measure the CL kiꢀ
netics, a powder of compound 1 (18.20 mg, 0.04 mmol) or 2
(15.92 mg, 0.04 mmol) was placed under argon on the bottom of
a glass cell mounted in a lightꢀtight chamber of the chemilumiꢀ
II
II
II
The Eu , Yb , and Sm compounds are rather stable,
E°(Ln /Ln ) = –(0.34—1.50 V) ), whereas the
compounds of other Ln (Ln = Nd, Dy, and Tm)
with very low oxidation potentials (E°(Ln /Ln ) =
(2.22—2.62 V)7 ) are extremely unstable; they have been
The properties of these
compounds were studied to less extent, and their CL has
not recently been examined. Therefore, investigation of
3
+
2+
7,8
(
II
1
2
3
+
2+
nescence setup. Water (2 mL) was added for 3 s from a doser to
the cell, and CL was detected. The spectra of CL arisen upon
the hydrolysis of compounds 1 (91.40 mg, 0.22 mmol) and 2
,8
–
9
—11
synthesized rather recently.
(
87.60 mg, 0.22 mmol) were measured using a set of cutꢀoff
1
3
color filters according to a known procedure with FEUꢀ39
for 1) and FEUꢀ83 (for 2) photomultipliers cooled with liquid
(
II
the physicochemical properties of the labile Nd and
nitrogen as light receivers. When measuring the CL spectra, an
aliquot of water (2 mL) was added to compound 1 (or 2) or
argon containing water vapor, which was obtained by purging
argon through a bottle filled with water, was supplied.
Reactions of compounds 1 and 2 with liquid water. The reacꢀ
tions were carried out in an ampule filled with argon and conꢀ
nected to a gas burette. Water (5 mL) was added dropwise at
II
Dy compounds is urgent.
In this work, we studied for the first time the ability of
DyI (1) and NdI (2) to enter chemical reactions and
generate radiative excited states Ln *. The interaction of
compounds 1 and 2 with water was chosen as this reacꢀ
tion. The reaction has not been studied earlier: CL was
not detected and no stable products were identified.
2
2
3
+
0
°С to compound 1 (1.39 g, 3.34 mmol). After gas evolution
ceased completely, more water (15 mL) was added to the reacꢀ
tion mixture, the mixture was centrifuged, and a light blue soluꢀ
tion was separated from the precipitate by decantation. The
precipitate was washed with MeOH (10 mL) and dried in vacuo.
The yield of DyI(OH) •H O was 0.494 g (82.4%). Found (%):
Experimental
Crystalline samples 1 and 2 (content of the main substance
2
2
9
5 and 93%, respectively) were synthesized according to earlier
Dy, 47.03; I, 38.26. H IDyO . Calculated (%): Dy, 47.59;
I, 37.17.
4 3
9
,10
described procedures.
Bidistilled water was used; THF was
purified by reflux over NaOH and metallic sodium and prior to
use it was kept for 15 min over compound 1 or 2 for the addiꢀ
tional purification from water traces.
The reaction of compound 2 with water was carried out
similarly. Diiodide 2 (1.28 g, 3.22 mmol) gave NdI(OH) •H O
2
2
(0.425 g, 74%). Found (%): I, 38.26; Nd, 45.74. H INdO .
4
3
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1890—1893, October, 2007.
1
066ꢀ5285/07/5610ꢀ1956 © 2007 Springer Science+Business Media, Inc.

Chemiluminescence of DyI and NdI in water
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 10, October, 2007
1957
2
2
Calculated (%): I, 39.27; Nd, 44.63. IR, ν/cm–1: 3250, 1600. As
ICL (rel. units)
found by complexonometry, the solution contained 0.84 g
(
100%) of NdI3.
15
Reaction of compound 2 with water vapor. An argon flow
bubbled through a water layer was purged above a layer of powꢀ
der 2 (0.549 g, 1.38 mmol) with periodical shaking. After 20 min,
the substance turned gray from dark violet. Water (10 mL) was
added to the powder, and no gas evolution was observed. A gray
suspension formed was centrifuged, and a precipitate was washed
with water (10 mL) and MeOH (10 ml) and dried. The yield of
NdI(OH) •H O was 0.141 g (67%). Found (%): I, 28.28;
1
0
5
2
1
0
2
2
40
ICL (rel. units)
80
120
t/s
Nd, 45.29. H INdO . Calculated (%): I, 39.27; Nd, 44.63.
4
3
IPL (rel. units)
Reaction of compound 2 with liquid water in THF. The reacꢀ
tion was carried out in an ampule in vacuo. A water solution in
THF (1.17 mol L–1) was added dropwise with iceꢀcooling to
compound 2 (0.559 g, 1.40 mmol). The vigorous reaction acꢀ
companied by gas evolution was observed for the first seconds.
A dark violet solution was formed on heating to room temperaꢀ
ture and stirring. After centrifuging, the solution was deꢀ
canted, and the solvent was removed in vacuo. Hydroxydiiodide
NdI OH(thf) •3H O as a pale blue solid was obtained in a
2
3
0.5
0
4
2
2
2
0
yield of 0.763 g (88.62%). Found (%): I, 19.91; Nd, 23.81.
–
1
400
500
λ/nm
C H I NdO . Calculated (%): I, 20.69; Nd, 23.53. IR, ν/cm
:
8
23 2
6
3
250, 1600, 1072, 1034, 1003, 915, 850.
The content of Dy or Nd in the products was deterꢀ
Fig. 1. Kinetics (1, 2) and the CL spectrum (3) for the reaction
of DyI (18.20 mg, 0.04 mmol) with H O (1, upon the addition
III
III
2
2
mined by complexonometric titration according to an earlier
described procedure14 (Xylenol Orange as indicator), and the
content of iodide ions was determined by the Volhard method.
Hydrogen was analyzed by GLC on a Tsvetꢀ800 chromatoꢀ
graph.
of 2 mL of H O; 2, upon the supply of an argon flow conꢀ
2
taining H O vapor) and the PL spectrum of a solution of
2
1
4
DyCl •3(BuO) PO in toluene (4), λ = 352 nm (according to
3
3
exc
2
0
published data ).
a longerꢀwavelength spectral region (700—1200 nm) charꢀ
2
0
3+
Results and Discussion
acteristic of the emission of the Nd * ion. The SZSꢀ9
color filter absorbs completely the CL, whereas the KSꢀ19
and FSꢀ6 color filters weaken the CL by 5 and 50%,
Individual inorganic compounds of bivalent lanꢀ
3
+
thanides Sm, Eu, and Yb in solutions at room temperaꢀ
respectively (see Fig. 2). These results indicate that Nd *
is the CL emitter in the hydrolysis of compound 2.
ture possess no PL.1
5—17
However, at 77 K the bright blue
PL appears in aqueous acidic solutions of EuCl and
To study the mechanism of CL generated in the reacꢀ
2
1
7
Eu(ClO ) . At the same time, the EuCl complexes with
tion of LnI with water, we identified the composition
4
2
2
2
1
8
crown ethers and chlorides LnCl (Ln = Sm, Eu, Yb)
and yield of the stable hydrolysis products of compounds
1 and 2 in particular experiments using larger amounts of
the reactants than those in CL measurements. Upon the
2
doped into inorganic matrices of NaCl, BaCl , and SrCl
exhibit the PL at room temperature as well. Published
2
2
1
5
data on the PL of compounds 1 and 2 and other iodides
dropwise addition of water to LnI , hydrogen evolved
2
LnI are lacking. We either found no PL for solid samples
of compounds 1 and 2 (300 and 77 K).
vigorously for several seconds (84—100%) and light preꢀ
2
3+
cipitates and pale yellow (color characteristic of Dy ions)
3
+
Upon the addition of liquid water to solid samples of
or pale blue (color characteristic of Nd ions) were
LnI under an argon flow, we found the rapidly decaying
formed. Due to the hydrolysis of LnI , a portion of lanꢀ
2
2
8
PL (Figs 1 and 2), whose intensity was I
= 5.4•10 and
thanides is transformed into a precipitate and a portion
goes to the solution. The presence in the solutions of
triiodides DyI and NdI , whose molar yield is 49—51%,
max
7
–1
–1
6
•10 photon s mL for compounds 1 and 2, respecꢀ
tively. Since the emission intensity was low, the CL spectra
were measured using boundary light filters. The CL specꢀ
trum of hydrolysis of compound 1 lies at 400—600 nm
and has maxima at 470 and 570 nm, whose positions
3
3
was established by titration. The corresponding lanꢀ
thanides and iodine in a ratio of 1 : 1 were found in the
precipitates. The IR spectrum of the precipitate contains
–
1
(
within the measurement error ±20 nm) coincide with
intense bands at 3200—3550 and 1600 cm assigned to
vibrations of the hydroxy groups in the molecule of water
those of the maxima in the PL spectra of salts
2
0
21
DyCl •6H O (see Ref. 19) and DyCl •3(BuO) PO, i.e.,
of crystallization. Against the broad absorption band of
3
2
3
3
3
+
the excited Dy * ion is the emitter of this CL. It was
found using the SZSꢀ9, KSꢀ19, and FSꢀ6 cutꢀoff color
filters that the CL for the hydrolysis of compound 2 lies in
water, the stretching vibrations of the hydroxy group in
2
1
the Ln—OH groups are observed as a weakly resolved
shoulder at 3565 cm–1. These results indicate that the

1
958
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 10, October, 2007
Bulgakov et al.
ICL (rel. units)
tions, dysprosium salt 1 gives only the DyI (OPh) diiodide
2
2
2
complex. It can be assumed that in water with much
1
1
0
.5
.0
.5
23
higher solvating and donating ability than that of THF
1
the processes of substituent redistribution at the metal ion
accelerate. As a result, the disproportionation products
are formed in an aqueous medium under the action of
even less reactive reducing agent 1. For the reactions with
water (as with phenol) it seems impossible to conclude
certainly about the starting compound of this process,
i.e., attribute it to LnI or LnI OH.
2
0
2
2
4
0
80
120
t/s
Another reaction occurs when a solution of water in
–
1
T (rel. units)
IPL (rel. units)
THF (1.17 mol L ) interacts with compound 2. In this
case, no precipitation was observed, but hydrogen evolved
vigorously (for several seconds) and the solution turned
dark violet. The solution contained neodymium and iodine
in a ratio of 1 : 2. The IR spectrum of the precipitate
isolated from this solution exhibits, in addition to the
absorption bands of water, bands at 1072, 1034, 1003,
4
1.2
1
0
.0
.5
6
5
0
0
.8
.4
–
1
9
15, and 850 cm attributed to vibrations of molecules of
3
2
1
coordinately bound THF. Based on the results obtained,
the composition of the precipitate can be described by the
formula NdI OH(thf) •3H O. The yield of the substance
2
2
2
2
00
400
600
800
1000
λ/nm
was 88.62%. Thus, the composition of the products of the
reaction of compound 2 with water in THF corresponds
to the equation
S (%)
1
00
8
7
NdI + H O
HONdI (thf) + 0.5 H .
2 2 2
2
2
The NdI OH(thf) •3H O complex in water remains
unchanged, indicating in favor of LnI2 (rather than
2
2
2
5
0
LnI OH) as the disproportionating substance during
2
diiodide hydrolysis in the absence of THF.
We believe that the motive force of the hydrolysis of
2
00
400
600
800
1000
λ/nm
2
+
3+
LnI are the low oxidation potentials of the Nd /Nd
2
Fig. 2. Kinetics in the absence (1) and presence of the KSꢀ19
light filter (2) and CL spectral parameters (3—5) for the reaction
of NdI (15.92 mg, 0.04 mmol) with H O (3, 4, and 5, transmitꢀ
2+
3+
and Dy /Dy pairs and the high coordinative unꢀ
saturation of the Nd and Dy ions. Taking into acꢀ
count the results obtained, we can present the mechanism
2+
2+
2
2
tance of the SZSꢀ9, KSꢀ19, and FSꢀ6 color filters, respectively),
the PL spectrum of a solution of NdCl •3(BuO) PO in toluꢀ
ene (6) (λexc = 337.1 nm, according to published data ), and
the spectral sensitivity (S) of FEUꢀ83 (7) and FEUꢀ39 (8).
of the hydrolysis of LnI as Scheme 1.
2
3
3
2
0
Scheme 1
precipitate composition corresponds to the formula
LnI(OH) •H O.
Ln2+ + HOH
2
2
Thus, the product composition of the reaction of comꢀ
pounds 1 and 2 with water differs from the expected one
Ln3+* + OH + H
–
•
(1)
(2)
(
LnI OH and H ) and corresponds to the equation
Ln3+
Ln = Dy, Nd
Ln3+ + hν
2
2
*
2
LnI + 2 H O
LnI + LnI(OH) + H .
3 2 2
2
2
The formation of triiodide NdI3 and monoiodide
NdI(OPh) instead of the NdI OPh diiodide complex has
previously been observed in the reactions of compound 2
with phenol in THF at –90 °С. These results were exꢀ
plained by the disproportionation of the starting diiodide
On contact with LnI the water molecules are incorꢀ
2
porated into the first coordination sphere of the lanꢀ
2
2
2
2
II
thanide, then an electron transfers from Ln to the water
II
III
molecule and, as a result, Ln is oxidized to Ln , and
atomic hydrogen is formed. The lanthanide ion transits to
3
+*
or primary product NdI OPh. Under the same condiꢀ
the excited state Ln (see Scheme 1, reaction (1)), which
2

Chemiluminescence of DyI and NdI in water
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 10, October, 2007
1959
2
2
is deactivated with photon emission (see Scheme 1, reacꢀ
tion (2)).
The energy values necessary for the population of the
Nd3+* (1.44 eV) and Dy3+* (2.68 eV) excited states were
6. R. G. Bulgakov, S. P. Kuleshov, V. N. Khandozhka, I. P.
Beletskaya, G. A. Tolstikov, and V. P. Kazakov, Dokl. Akad.
Nauk SSSR, 1989, 304, 114 [Dokl. Chem., 1989 (Engl.
Transl.)].
7
. N. B. Mikheev, Zh. Neorg. Khim., 1984, 29, 450 [J. Inorg.
Chem. USSR, 1984, 29 (Engl. Transl.)].
estimated from the positions of the shortꢀwavelength
maxima in the PL spectra (see Figs 1 and 2). The free
Gibbs energy (∆G°) of reaction (1) (see Scheme 1) was
determined by the known2 Weller equation
8
. L. J. Nugent, R. D. Baybarz, J. L. Burnett, and J. L. Ryan,
J. Phys. Chem., 1973, 77, 1528.
4
9. M. N. Bochkarev and A. A. Fagin, Chem. Eur. I., 1999,
, 2990.
5
•
–
∆
G° (eV) = E°(Ln3+/Ln2+) – E°(H O/H ,OH ) –
2
1
1
0. M. A. Katkova, G. K. Fukin, A. A. Fagin, and M. N.
Bochkarev, J. Organomet. Chem., 2003, 682, 218.
2
ke /(εr) – E*(Ln3+),
–
(I)
1. M. N. Bochkarev, I. L. Fedushkin, A. A. Fagin, T. V.
Petrovskaya, J. W. Ziller, R. N. R. BroomhallꢀDillard, and
W. J. Evans, Angew. Chem., Int. Ed., 1997, 35, 133.
2. R. G. Bulgakov, V. P. Kazakov, and G. A. Tolstikov,
Khemilyuminestsentsiya metalloorganicheskikh soedinenii
[Chemiluminescence of Organometallic Compounds], Nauka,
Moscow, 1989, 220 pp. (in Russian).
where E°(Ln3+/Ln2+) and E°(H O/H ,OH ) are the oxiꢀ
•
–
2
II
dation potential of the Ln ion and the reduction potenꢀ
tial of water, respectively; E*(Ln3 ) is the energy of
the excited state of the CL emitter; k is the Boltzmann
constant; е is the electron charge; ε is the dielectric
+
1
2
5
constant of the solvent (for water 78.5) ; r is the disꢀ
II
26
13. R. F. Vasil´ev, Optika i spektroskopiya [Optics and Spectroꢀ
scopy], 1965, 18, 236 (in Russian).
tance between the Ln atom and H O (0.5 nm). The
2
3
+
2+ 8
substitution of the corresponding E°(Ln /Ln ) and
E°(H O/H ,OH ) values into Eq. (I) gave the ∆G° valꢀ
1
4. G. Charlot, Les Methodes de la Chimie Analytique. Analyse
•
– 27
2
ie
Quantitative Minerale, Masson et C Ed´iteurs, Paris, 1961.
ues for the hydrolysis of compounds 1 and 2
1
5. F. Butement, Trans. Faraday Soc., 1948, 309, 617.
G° = E°(Dy3+/Dy2+) – E°(H O/H ,OH ) –
•
–
16. Y. Haas, G. Stein, and M. Tomkiewicz, J. Chem. Phys.,
970, 74, 2558.
∆
2
1
ke /(εr) – E*(Dy3+) =
2
–
=
1
7. R. G. Bulgakov, V. P. Kazakov, and V. N. Korobeinikov,
–2.56 – (–0.41) – 0.04 – 2.68 = –4.87 (eV),
(II)
Optika i spektroskopiya [Optics and Spectroscopy], 1973, 35,
8
50 (in Russian).
•
–
∆
G° = E°(Nd3+/Nd2+) – E°(H O/H ,OH ) –
ke /(εr) – E*(Nd3+) =
2
2
18. G. Adachi, K. Tomokiyo, K. Sorita, and J. Shiokawa,
–
=
J. Chem. Soc., Chem. Commun., 1980, 914.
1
9. N. S. Poluektov, L. I. Kononenko, N. P. Efryushina, and
S. V. Bel´tyukova, Spektrofotometricheskie i lyuminestsentnye
metody opredeleniya lantanidov [Spectrophotometric and Luꢀ
minescence Determination of Lanthanides], Naukova Dumka,
Kiev, 1989, 254 pp. (in Russian).
–2.62 – (–0.41) – 0.04 – 1.44 = –3.69 (eV).
(III)
The resulting ∆G° values indicate that electron transꢀ
fer from the both Ln atoms is an exothermic process and
the amount of the evolved energy is quite sufficient for the
formation of the Dy3+* and Nd3+* ions.
Thus, the CL accompanying the reactions of iodides
DyI and NdI with water was found and studied for the
II
20. R. G. Bulgakov, S. P. Kuleshov, A. N. Zuzlov, I. R.
Mullagaleev, and L. M. Khalilov, J. Organomet. Chem., 2001,
6
21. K. Nakamoto, Infrared and Raman Spectra of Inorganic
and Coordination Compounds, John Wiley and Sons, New
York, 1986.
36, 56.
2
2
first time, the products were identified, and the energy
parameters of the process were estimated.
2
2. M. N. Bochkarev, A. A. Fagin, and G. V. Khoroshen´kov,
Izv. Akad. Nauk, Ser. Khim., 2002, 1757 [Russ. Chem. Bull.,
Int. Ed., 2002, 51, 1909].
3. A. F. Popov and Zh. P. Piskunov, Struktura i osnovnost´
aminov v problemakh fizikoꢀorganicheskoi khimii [Structure
and Basicity of Amines in Problems of Physical Organic Chemꢀ
istry], Naukova Dumka, Kiev, 1978, 44 pp. (in Russian).
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 04ꢀ03ꢀ
3
2093).
2
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Received December 11, 2006;
in revised form June 22, 2007