This document summarizes research on interparticle interactions and dynamics in solutions of zinc perchlorate in acetonitrile at temperatures of 5-55°C. Conductometric studies showed that zinc ions associate with perchlorate ions through two equilibria. Molecular dynamics simulations in two systems identified solvation shells around ions and determined that zinc forms contact ion pairs with chlorate at short distances. Dynamics analysis found that diffusion and reorientation of acetonitrile and ions decreases with proximity to other species due to stronger interactions within inner solvation shells.

1. INTERPARTICLE INTERACTIONS AND DYNAMICS IN SOLUTIONS OF ZINC PERCHLORATE IN
ACETONITRILE AT 5-55 OC
Karazin Kharkiv national University
IX INTERNATIONAL CONFERENCE IN CHEMISTRY KYIV-TOULOUSE (ICKT-9)
report
Report: Dmitry Novikov
In collaboration with: Oleg Kalugin
Evgennia Smortsova
Vira Agieienko
KYIV 2017

2. RESULTS OF CONDUCTOMETRIC STUDY
0.02 0.04 0.06
120
140
160
180
200
220
240
260
eq
/Om
-1
cm
2
mol
-1
5.00
0
C
15.00
0
C
25.00
0
C
35.00
0
C
45.00
0
C
55.00
0
C
(c / mol dm
-3
)
1/2
𝑙𝑛𝛾± = −
1
2
𝜅𝛽
1 + 𝑅𝜅
𝑐𝑗
𝑠𝑡
=
𝑗=1
𝑚
𝜈𝑖𝑙 𝑐 𝑘𝑙
𝐾𝐴𝑖= 𝑐 𝑘𝑖 𝑦 𝑘𝑖
𝑙=1
𝑞
𝑎 𝑘𝑙
−𝑣 𝑖𝑙
𝑄 =
𝑘=1
𝑁
𝛬 𝑒𝑞,𝑘
𝑒𝑥𝑝
− 𝛬 𝑒𝑞,𝑘
𝑡ℎ𝑒𝑜𝑟
(𝐀))
2
⇒ 𝑚𝑖𝑛
Fig 1. Equivalent conductivity of Zinc perchlorate in acetonitrile as a
function of square root of concentration
Zn2+ + ClO4
- ↔ ZnClO4
+, KAI, (1)
ZnClO4
+ + ClO4
- ↔ Zn(ClO4)2, KAII, (2)
𝐴 = { 𝛬0 1
2
Zn(𝐶𝑙𝑂4)2, 𝜆0
ZnClO4
+
, lg𝐾𝐴𝐼, lg𝐾𝐴𝐼𝐼, 𝑡+ 1
2
Zn2+
, 𝑅 , (3)
𝜆𝑗
= 𝜆𝑗
0
1 + 𝑧𝑗
𝑝=2
𝑠
𝜒 𝑗
𝑝
𝑣=1
𝑠
𝑡 𝑣 𝜒 𝑣
𝑝
𝐴 𝑣
𝑝
𝑡 ∙ 𝛽𝜅 + 𝐵𝑣
𝑝
𝑡 𝛽𝜅 2
+ 𝐶𝑣
𝑝
𝑡 𝛽𝜅 3
(4)
(5)
(6)
(7)
(8) 3
IX INTERNATIONAL CONFERENCE IN CHEMISTRY KYIV-
TOULOUSE (ICKT-9)

3. RESULTS OF CONDUCTOMETRIC STUDY
Zn2+ + ClO4
- ↔ ZnClO4
+, KAI
ZnClO4
+ + ClO4
- ↔ Zn(ClO4)2, KAII
Table 1. Results of conductometric data processing
t, ℃ 𝜆0
(ZnClO4
+
) /
Sm cm2 mol-1
lg𝐾 𝐴𝐼
σΛ /
Sm cm2 mol-1
5 0C 14±7 2.340.03 0.49
15 0C 19±3 2.380.01 0.63
25 0C 17±4 2.3700.08 0.77
35 0C - - 0.73
45 0C 11.3±9 2.410.03 0.77
55 0C 6.6±2 2.420.01 0.74Fig 2. Equivalent electrical conductivity of 𝑍𝑛2+
and 𝐶𝑙𝑂4
−
as a function of concentration
𝐀 = { 𝛬0
(
1
2
Zn ClO4)2 , 𝜆0
ZnClO4
+
, lg𝐾𝐴𝐼, 𝑡+
(
1
2
Zn2+
) (9)
4
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4. RESULTS OF CONDUCTOMETRIC STUDY
𝐾𝐴𝐼 =
4𝜋𝑁𝐴
103
exp −
𝑑±
𝑘 𝐵 𝑇
∗ 𝐾𝐴
𝐶𝑜𝑢𝑙
𝑎 − 𝐾𝐴
𝐶𝑜𝑢𝑙
𝑅 + 𝐾𝐴
𝐶𝑜𝑢𝑙
(𝑅
0 10 20 30 40 50 60
3.25
3.50
3.75
4.00
4.25
4.50
4.75
5.00
5.25
dNA
,kJ/mol
t, o
C
Fig 3. Temperature function of short range non-Coulomb potential
𝑅 𝑆𝑡 =
𝑧𝑒𝐹
4𝜋𝜂𝜆0
0 20 40 60
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
Zn
2+
ClO
4

R
St
-R
i
/10
10
m
t /
o
C
0
Fig 4. Temperature function of thicknesses of ionic solvation shells
(10) (11)
5
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5. DETAILS OF MOLECULAR DYNAMIC SIMULATIONS
Тип атома Масса Заряд σ, нм ε, кДж/моль
#atom C1
12.0112 -0.5503 0.3400 0.45729
#atom H 1.0079 0.1904 0.2500 0.03000
#atom C2
12.0112 0.4917 0.3546 0.056054
#atom N 14.0067 -0.5126 0.3100 0.556360
#atom Zn 65.3820 2.0000 0.0971 1192.44
#atom Cl 35.4527 1.309458 0.486 0.168
#atom O 15.9994 -0.577365 0.310 0.3168
Table 2. Force field parameters of modelled particles *
STEPS OF MODELLING:
1. System initiation (1 ps)
2. System equilibration (250 ps)
3. Study of structure (500 ps)
4. Study of dynamic properties (500 ps)
Cut-off radius: 1.33933 нм
Ensemble: NVT
Thermostat relaxation time: 0.05 пс
Dielectric constant: 36.0
Temperature: 298.15 К
Density of system: 776.8 кг/м3
System (I) System (II)
*- AN: Nikitin A., J. Copm. Chem. – 2007 – Vol. 28, P. 2020-2026.
Zn: Torras J.,J. Phys. Chem. – 2013 –Vol. 117. – P. 10513-10522
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6. DETERMINATION OF SOLVATION SHELLS BOUNDARIES AND IDENTIFICATION OF
CONTACT ION PAIR FORMATION
Fig 5. Radial density function of 𝑍𝑛2+
and 𝑍𝑛𝐶𝑙𝑂4
+
in acetonitrile
System Coordination number of 𝑍𝑛2+
(AN)
(I) 8
(II) 7
Таблица 3. Running coordination numbers of 𝑍𝑛2+
in systems (I) and (II)
0.2 0.3 0.4 0.5 0.6
0.0
2.5
5.0
7.5
10.0
12.5
15.0
17.5
20.0
nij
(r)
gij
(r)
r, nm
Zn...Cl (II)
Zn...N (II)
Zn (I)
Zn (II)
FSS
Zn…N
0.301 nm
d(CIP)
Zn…Cl
0.393 nm
7
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7. DYNAMIC OF 𝒁𝒏 𝟐+ and 𝒁𝒏𝑪𝒍𝑶 𝟒
+
Fig 6. ACF of linear velocity of 𝑍𝑛2+
in systems (I) and (II) and 𝑍𝑛𝐶𝑙𝑂4
+
in system (II)
Fig 7. Spectra of linear velocity ACF for 𝑍𝑛2+
in systems (I) and (II) and
𝑍𝑛𝐶𝑙𝑂4
+
in system (II)
С 𝑉𝑉 𝑡 =
< 𝑽 0 𝑽 𝑡 >
𝑽2(0)
=
< 𝑽 0 𝑽 𝑡 > 𝑚
3𝑘 𝐵 𝑇
𝑆 𝑉𝑉 𝑤 =
0
∞
С 𝑉𝑉 𝑡 cos 𝑤𝑡 𝑑𝑡
0.0 0.5 1.0 1.5 2.0
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Cvv
(t)
t, ps
Cvv
(Zn) - (I)
Cvv
(Zn) - (II)
Cvv
(ClO-
4
) - (II)
0 200 400 600 800 1000
-0.01
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
S
(Zn) - (I)
S
(Zn) - (II)
S
(ClO-
4
) - (II)
S
()
,THz
(12) (13)
8
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𝑛2+
𝑂4
+

8. ACETONITRILE DYNAMICS
С 𝑉𝑉 𝑡 =
< 𝑽 0 𝑽 𝑡 >
𝑽2(0)
=
< 𝑽 0 𝑽 𝑡 > 𝑚
3𝑘 𝐵 𝑇
𝑆 𝑉𝑉 𝑤 =
0
∞
С 𝑉𝑉 𝑡 cos 𝑤𝑡 𝑑𝑡
𝐷 =
1
3
0
∞
С 𝑉𝑉 𝑡 𝑑𝑡
Table 4. Coefficients of translational self-diffusion for acetonitrile
molecules by solvation shells in systems studied
Fig 8. Linear velocity ACF for acetonitrile by solvation shells
Fig 9. Linear velocity ACF spectra for acetonitrile by solvation shells
0.0 0.5 1.0 1.5 2.0
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
Cvv
(t)
t, ps
Cvv(AN) - Pure AN
Cvv(AN) - (I)
Cvv(AN) - (II)
0 200 400 600 800 1000
0.00
0.01
0.02
0.03
0.04
0.05
Cvv(AN) - Pure AN
Cvv(AN) - (I)
Cvv(AN) - (II)
S
()
, THz
D∙1010, m2s-1
(I) (II)
Bulk 3.73 3.80
SSS 1.68 -
FSS 0.82 0.66
ION 0.59 0.54
(12)
(13)
(14)
9
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9. RESULTS OF THE DYNAMIC PROPERTIES STUDY
(I) Dipole momentum
reorientation time
Lifetime by solvation shells
Bulk 3.07 ps -
SSS 7.87 ps 15.76 ps
FSS 68.21 ps 255.75 ps
(II) Dipole momentum
reorientation time
Lifetime by solvation shells
Bulk 3.11 ps -
FSS 91.07 ps 79.81 пс
С1𝜇 𝑡 = 𝑐𝑜𝑛𝑠𝑡 + exp −
𝑡
𝜏1𝜇
С 𝑟𝑡 𝑡 = 𝑐𝑜𝑛𝑠𝑡 + exp −
𝑡
𝜏 𝑟𝑡
Fig 10. Dipole momentum reorientation time ACF
Fig 11. Lifetime ACF by solvation shells
Table 5. Results of dipole momentum reorientation time and lifetime
ACF study
0 1 2 3 4 5
-2.0
-1.5
-1.0
-0.5
0.0
Bulk - (I)
SSS - (I)
FSS - (I)
Bulk - (II)
FSS - (II)
lnC1
(t)
t ,ps
0.0 0.5 1.0 1.5 2.0
-0.4
-0.3
-0.2
-0.1
0.0
SSS - (I)
FSS - (I)
FSS - (II)
lnCrt
(t)
t, ps
𝜇
(15)
(16)
10