Design and screening of suitable ligand/diluents systems for removal of Sr 2+ ion from nuclear waste: Density functional theoretical modelling Sk. Musharaf Ali *# Chemical Engineering Division Bhabha Atomic Research centre, Mumbai, India, 400085 # Homi Bhabha National Institute E-mail: [email protected]Section-S1 Structural parameters The calculated distance of Sr 2+ metal ion from the plane of the crown ether ring is displayed in supplementary Fig.S2. In 12C4, the metal ion is above the plane of the cavity by 1.55Å and in 15C5 by 1.03 Å, whereas it is almost zero in case of 18C6. The calculated C-C (1.51- 1.52Å) bond length remains almost unchanged after complexation though the C-O bond is lengthened from 1.42-1.42Å to 1.45-1.46 Å for all the crown ethers studied here. Detailed structural parameters are given in supplementary table, Table. S1.The O-O distance is reduced due to electrostatic interaction between the metal ion and the crown ether. The calculated C-C (1.51-1.52Å) bond distance within the crown ether cavity is in excellent agreement with the reported experimental results of 1.50-1.53Å 86 . Detailed results are presented in Table. S2. There are two types of C-O bonds. The C-O bond distance, where the O atom is bonded to the benzene carbon is smaller in length (1.37Å; experimental C-O: 1.36-1.37Å) than the methylene carbon atom of the crown ring, 1.42-1.43Å (experimental results: 1.39-1.46Å). This is due to the smaller C-C bond length of the benzene ring. The calculated <CCO bond angle (108.22 o -116.56 o ) are well matched with the experimental results (104.3 o -126.2 o ). The calculated <COC bond angle (112.39 o -118.28 o ) are also well matched with the experimental results (112.4 o -119 o ).
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Design and screening of suitable ligand/diluents systems for removal of Sr2+ ion from
nuclear waste: Density functional theoretical modelling
Sk. Musharaf Ali*#
Chemical Engineering Division Bhabha Atomic Research centre, Mumbai, India, 400085
The calculated distance of Sr2+ metal ion from the plane of the crown ether ring is displayed in supplementary Fig.S2. In 12C4, the metal ion is above the plane of the cavity by 1.55Å and in 15C5 by 1.03 Å, whereas it is almost zero in case of 18C6. The calculated C-C (1.51-1.52Å) bond length remains almost unchanged after complexation though the C-O bond is lengthened from 1.42-1.42Å to 1.45-1.46 Å for all the crown ethers studied here. Detailed structural parameters are given in supplementary table, Table. S1.The O-O distance is reduced due to electrostatic interaction between the metal ion and the crown ether.
The calculated C-C (1.51-1.52Å) bond distance within the crown ether cavity is in excellent agreement with the reported experimental results of 1.50-1.53Å86. Detailed results are presented in Table. S2. There are two types of C-O bonds. The C-O bond distance, where the O atom is bonded to the benzene carbon is smaller in length (1.37Å; experimental C-O: 1.36-1.37Å) than the methylene carbon atom of the crown ring, 1.42-1.43Å (experimental results: 1.39-1.46Å). This is due to the smaller C-C bond length of the benzene ring. The calculated <CCO bond angle (108.22o-116.56o) are well matched with the experimental results (104.3o-126.2o). The calculated <COC bond angle (112.39o-118.28o) are also well matched with the experimental results (112.4o-119o).
The interaction energy of DB18C6 with Sr2+ ion can be further tuned by replacing the hard donor “O”
atom with the soft donor “N” and hence N atom substituted structure (aza-DB18C6) was further
optimized at BP86/TZVP level and are displayed in Fig.S3(II). The C-C bond lengths are similar like
DB18C6. The C-N bond lengths is (1.38-1.41Å and 1.38-1.43Å, adjacent to the benzene ring) smaller
than the C-O bond length of DB18C6. Few <NCC and <CNC bond angles are large compared to <OCC
and <COC bond angles in DB18C6 (see the supplementary Table. S2). The centre to centre transannular
N-N distance (5.10-5.46Å) is smaller than the O-O distance due to which the cavity size is reduced
slightly. The optimized structure of Sr2+ complex with aza-DB18C6 is also displayed in the same Fig.
S3(III). Though the C-C bond remains almost unaffected, the C-O bond has been lengthened by ~0.3 due
to the interaction with the Sr2+ metal ion in DB18C6. The change in the <OCC and <COC bond angle
was also found to be insignificant. The minimum Sr-O bond distance is found to be increased from 12C4
Structural parameters of Sr2+ and Sr(NO3)2-crown ether complexes at BP86/TZVP level of theory.
Ligand
M-O distance (Å) O-O annular distance (Å)
calc
Middle O
O adjacent to benzene/ cyclohexane ring
O of nitrate Middle O O adjacent to benzene / cyclohexane ring
CSCDCH 2.710, 2.660
2.719, 2.725, 2.840, 2.775
2.723, 2.713, 2.708, 2.690
5.182 5.485, 5.552
CSCDTBDCH 2.677, 2.733
2.783, 2.763, 2.765, 2.859
2.620, 2.614, 2.659, 2.651
5.195 5.608, 5.534
Table.S11. Calculated values of second order stabilization energies Eij(2) using NBO analysis as
implemented in ADF Package at BP86/TZ2P level of theory.
18C6-Sr
S.No Donor NBO Acceptor NBO E(2) kcal/mol
1 BD(1) C1-H(35) LP* (1) Sr (43) 1.07
2 BD(1) C2-H(38) LP* (1) Sr (43) 1.50
3 BD(1) C3-H(25) LP* (1) Sr (43) 1.26
4 BD(1) C4-H(24) LP* (1) Sr (43) 1.27
5 BD(1) C5-H(22) LP* (1) Sr (43) 1.47
6 BD(1) C6-H(20) LP* (1) Sr (43) 1.10
7 BD(1) C7-H(42) LP* (1) Sr (43) 1.37
8 BD(1) C8-O(16) LP* (1) Sr (43) 1.03
9 BD(1) C8-H(39) LP* (1) Sr (43) 1.22
10 BD(1) C9-C(10) LP* (1) Sr (43) 1.17
11 BD(1) C9-O(16) LP* (1) Sr (43) 1.10
12 BD(1) C9-H(33) LP* (1) Sr (43) 1.15
13 BD(1) C10-O(17) LP* (1) Sr (43) 1.00
14 BD(1) C10-H(31) LP* (1) Sr (43) 1.19
15 BD(1) C11-O(17) LP* (1) Sr (43) 1.05
16 BD(1) C11-H(30) LP* (1) Sr (43) 1.25
17 BD(1) C12-H(27) LP* (1) Sr (43) 1.31
18 LP (1) O13 LP* (1) Sr (43) 1.34
19 LP (1) O14 LP* (1) Sr (43) 1.33
20 LP (1) O15 LP* (1) Sr (43) 1.57
21 LP (1) O16 LP* (1) Sr (43) 1.44
22 LP (1) O17 LP* (1) Sr (43) 1.42
23 LP (1) O18 LP* (1) Sr (43) 1.58
SUM 28.10
DTBDCH18C6-Sr
S.No Donor NBO Acceptor NBO E(2) kcal/mol
1 BD(1) C20-H(51) LP* (1) Sr (35) 1.56
2 BD(1) C17-H(55) LP* (1) Sr (35) 2.04
3 BD(1) C10-H(36) LP* (1) Sr (35) 2.01
4 BD(1) C4-H(49) LP* (1) Sr (35) 1.53
5 BD(1) C2-C(3) LP* (1) Sr (35) 1.46
6 BD(1) C2-O(29) LP* (1) Sr (35) 1.25
7 BD(1) C2-H(68) LP* (1) Sr (35) 1.13
8 BD(1) C3-C(4) LP* (1) Sr (35) 1.41
9 BD(1) C3-O(34) LP* (1) Sr (35) 1.31
10 BD(1) C7-C(8) LP* (1) Sr (35) 1.06
11 BD(1) C7-O(29) LP* (1) Sr (35) 1.08
12 BD(1) C7-H(42) LP* (1) Sr (35) 1.65
13 BD(1) C8-O(30) LP* (1) Sr (35) 1.03
14 BD(1) C8-H(41) LP* (1) Sr (35) 1.83
15 BD(1) C9-C(10) LP* (1) Sr (35) 1.14
16 BD(1) C9-O(30) LP* (1) Sr (35) 1.07
17 BD(1) C9-H(39) LP* (1) Sr (35) 1.41
18 BD(1) C11-C(16) LP* (1) Sr (35) 1.45
19 BD(1) C11-O(31) LP* (1) Sr (35) 1.06
20 BD(1) C11-H(67) LP* (1) Sr (35) 1.00
21 BD(1) C15-H(60) LP* (1) Sr (35) 1.10
22 BD(1) C17-C(18) LP* (1) Sr (35) 1.11
23 BD(1) C17-O(32) LP* (1) Sr (35) 1.11
24 BD(1) C18-O(33) LP* (1) Sr (35) 1.03
25 BD(1) C18-H(56) LP* (1) Sr (35) 1.51
26 BD(1) C19-C(20) LP* (1) Sr (35) 1.28
27 BD(1) C19-O(33) LP* (1) Sr (35) 1.11
28 BD(1) C19-H(53) LP* (1) Sr (35) 1.41
29 LP (1) O29 LP* (1) Sr (35) 1.22
30 LP (1) O30 LP* (1) Sr (35) 1.32
31 LP (1) O31 LP* (1) Sr (35) 1.10
32 LP (1) O32 LP* (1) Sr (35) 1.33
33 LP (1) O33 LP* (1) Sr (35) 1.40
34 LP (1) O34 LP* (1) Sr (35) 1.16
SUM 44.65
DCH18C6-Sr
S.No Donor NBO Acceptor NBO E(2) kcal/mol
1 BD(1) C2-C(3) LP* (1) Sr (27) 1.45
2 BD(1) C3-O(26) LP* (1) Sr (27) 1.48
3 BD(1) C4-H(53) LP* (1) Sr (27) 1.52
4 BD(1) C7-H(28) LP* (1) Sr (27) 2.03
5 BD(1) C9-H(33) LP* (1) Sr (27) 1.85
6 BD(1) C10-H(34) LP* (1) Sr (27) 1.52
7 BD(1) C13-H(42) LP* (1) Sr (27) 2.14
8 BD(1) C20-H(51) LP* (1) Sr (27) 1.91
9 BD(1) C2-O(21) LP* (1) Sr (27) 1.22
10 BD(1) C7-C(8) LP* (1) Sr (27) 1.15
11 BD(1) C7-O(21) LP* (1) Sr (27) 1.09
12 BD(1) C8-O(22) LP* (1) Sr (27) 1.21
13 BD(1) C8-H(31) LP* (1) Sr (27) 1.29
14 BD(1) C9-C(10) LP* (1) Sr (27) 1.09
15 BD(1) C9-O(22) LP* (1) Sr (27) 1.20
16 BD(1) C10-O(23) LP* (1) Sr (27) 1.24
17 BD(1) C11-C(12) LP* (1) Sr (27) 1.48
18 BD(1) C11-O(23) LP* (1) Sr (27) 1.42
19 BD(1) C11-H(62) LP* (1) Sr (27) 1.09
20 BD(1) C11-C(13) LP* (1) Sr (27) 1.35
21 BD(1) C12-O(24) LP* (1) Sr (27) 1.59
22 BD(1) C17-C(18) LP* (1) Sr (27) 1.26
23 BD(1) C17-O(24) LP* (1) Sr (27) 1.15
24 BD(1) C17-H(44) LP* (1) Sr (27) 1.52
25 BD(1) C18-O(25) LP* (1) Sr (27) 1.22
26 BD(1) C18-H(46) LP* (1) Sr (27) 1.31
27 BD(1) C19-C(20) LP* (1) Sr (27) 1.12
28 BD(1) C19-O(25) LP* (1) Sr (27) 1.18
29 BD(1) C19-H(49) LP* (1) Sr (27) 1.41
30 BD(1) C20-O(26) LP* (1) Sr (27) 1.31
31 LP (1) O21 LP* (1) Sr (27) 1.41
32 LP (1) O22 LP* (1) Sr (27) 1.65
33 LP (1) O23 LP* (1) Sr (27) 1.54
34 LP (1) O24 LP* (1) Sr (27) 1.44
35 LP (1) O25 LP* (1) Sr (27) 1.78
36 LP (1) O26 LP* (1) Sr (27) 1.61
SUM 52.44
DB18C6-Sr
S.No Donor NBO Acceptor NBO E(2) kcal/mol
1 BD(1) C1-O(26) LP* (1) Sr (27) 1.06
2 BD(1) C8-H(41) LP* (1) Sr (27) 1.11
3 BD(1) C19-O(25) LP* (1) Sr (27) 1.12
4 BD(1) C20-O(26) LP* (1) Sr (27) 1.03
5 LP (1) O21 LP* (1) Sr (27) 2.27
6 LP (1) O22 LP* (1) Sr (27) 2.25
7 LP (1) O23 LP* (1) Sr (27) 2.31
8 LP (1) O24 LP* (1) Sr (27) 2.45
9 LP (1) O25 LP* (1) Sr (27) 2.35
10 LP (1) O26 LP* (1) Sr (27) 2.39
SUM 18.34
(side view) (top view)
I
II
III
3.48Å
4.76Å
2.45Å
2.51Å
4.14Å
4.90Å
2.50Å
2.53Å
5.16Å
5.89Å
6.15Å
2.59Å
2.63Å
4.13Å
3.57Å
Fig.S1. Fully optimized minimum energy structure at BP86 level of theory using TZVP basis function of (I) 12-crown-4 and its Sr2+ complex, (II) 15-crown-5 and its Sr2+ complex and (III) 18-crown-6 and its Sr2+ complex.
I II
III IV
V VI
Fig. S2. Calculated distance of Sr2+ ion from the molecular plane. (I) 12C4-Sr2+ (II) 15C5-Sr2+ (III) 12C4-Sr(NO3)2 (IV) 15C5-Sr(NO3)2H2O (V) 18C6-Sr2+ and (VI) 18C6-Sr(NO3)2.
I
II
III
Fig. S3. Fully optimized minimum energy structures of (I) DB18C6 and (II) Aza-DB18C6 and Sr2+-aza-DB18C6 at same level of theory as in Fig.1. The key is same as in Fig.1. The light yellow sphere represents the nitrogen atom.
I II III
IV V VI
VII
Fig. S4. Calculated angle between the planes of two benzene ring of DB18C6 with (I) Sr2+, (II) Be2+, (III) Mg2+, (IV) Ca2+, (V) Ba2+, (VI) Na+ and (VII) H3O+
ion.
Ligand Free Complex of Sr2+ ionHOMO LUMO HOMO LUMO
18C6
DB18C6
aza-DB18C6
Fig.S5. Calculated HOMO-LUMO of few crown ethers and its Sr2+ ion complexes.
I
II
Fig.S6. Fully optimized minimum energy structure of (I) DCH18C6 and (II) DTBDCH18C6.