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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
#Homi Bhabha National Institute
E-mail: [email protected]
Section-S1
Structural parameters
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
(2.46Å) to 18C6 (2.60Å) and then is decreased in DB18C6 (2.56Å). This is due to the increase in cavity
size from 12C4 to 18C6 and then cavity size is reduced in DB18C6. The O-O distance is reduced due to
electrostatic interaction between the metal ion and the crown ether. The cavity size in DB18C6 is
reduced to 2.23Å from 2.76Å due to strong electrostatic interaction of the ring O atom with the metal ion
and hence the ion is slightly pulled off from the cavity. The Sr-O bond distance adjacent to the benzene
ring is larger than with the methylene O atom of the crown ring. The C-C bond length remains
unchanged in aza-DB18C6-Sr2+ ion complex. The C-N bond is lengthened compared to the free crown
part. The Sr-N bond distance (2.69-2.77Å) is larger than the Sr-O bond distance (2.55-2.60Å). The two
benzene ring in aza complex has come closer than the corresponding oxa complex as clearly seen in the
figure.
Table.S1. Calculated structural parameters of Sr2+ ion complexes with different crown ethers at BP86/TZVP level of theory.
Ligand Bond distance (Ǻ)
(gas) Sr-O(N) Trans annular O-O (N-N)distance
C-C C-O(N) min max min max
12C4 1.519 1.455 2.458 2.514 3.573 4.131
15C5 1.512 1.453 2.503 2.533 3.992 4.577
18C6 1.505 1.448 2.595 2.634 5.103 5.262
DB18C6 1.507 1.403*
1.449
2.557 2.605 4.823 5.166
Aza-DB18C6 1.531 1.438*
1.491
2.691 2.783 5.064 5.373
*adjacent to benzo ring
Table.S2. Calculated structural parameters of DB18C6 and aza-DB18C6 at BP86/TZVP level of theory in gas phase.
Ligand Bond distance (Ǻ)
(gas)
C-C C-O(N) C-O(N)* <OCC <COC O-O
DB18C6 1.513, 1.512, 1.523,1.514
(1.53, 1.532, 1.502, 1.50, )
1.418, 1.420, 1.425, 1.428, 1.425, 1.419,
(1.437, 1.42, 1.39, 1.45,
1.441, 1.419, 1.466, 1.446)
1.364, 1.364, 1.364, 1.368
(1.355, 1.355, 1.368, 1.369)
108.33, 109.60, 116.56, 109.49, 108.22, 109.5, 110.09, 108.30
(107.9, 107.4, 112.4, 107.3, 105.9, 114.6, 124.5, 126.2, 114.5, 107.3, 114.6, 105,
104.3, 123.4, 116.1,
112.39, 117.80, 114.75, 117.32, 118.23, 118.28
(118.2, 113.4, 117.8, 117.5, 112.4, 119.0
5.282
5.500
5.624
Aza-DB18C6 1.527
1.524
1.528
1.536
1.477, 1.463
1.465, 1.464
1.467, 1.444
1.449, 1.442
1.388
1.431
1.381
1.406
113.83, 111.74
109.28, 112.37
111.31, 111.01
110.82, 109.42
117.01, 117.82, 118.32, 118.02
114.01, 124.93
121.26, 113.96
120.26, 113.87
5.131
5.463
5.104
*adjacent to benzo ring
Table.S3. Calculated structural parameters of different free crown ethers in solvent at BP86/TZVP level of theory.
Ligand Bond distance (Ǻ)
(gas) (water) (Chloroform) (Nitrobenzene)
C-C C-O C-C C-O C-C C-O C-C C-O
12C4 1.517 1.420 1.515 1.426 1.516 1.425 1.515 1.428
15C5 1.514 1.417 1.512 1.424 1.513 1.422 1.512 1.424
18C6 1.513 1.416 1.512 1.426 1.513 1.422 1.512 1.425
DB18C6 1.512 1.364*
1.418
1.509 1.366*
1.425
1.510 1.365*
1.423
1.510 1.365*
1.425
*O atom adjacent to benzo ring
Table.S4. Calculated structural parameters of different crown ethers at BP86/TZVP level of theory.
Ligand Centre-centre transannular O-O distance(Å)
(gas) (water) (Chloroform) (Nitrobenzene)
12C4 3.484
4.767
3.508
4.709
3.509
4.723
3.520
4.701
15C5* 4.148
4.479
4.708
4.904
4.070
4.379
4.738
4.987
4.113
4.437
4.726
4.954
4.073
4.384
4.736
4.984
18C6 5.161
5.893
6.151
4.384
5.903
5.939
4.353
5.941
5.948
4.360
5.931
5.940
DB18C6 5.282
5.500
5.624
5.290
5.509
5.580
5.294
5.507
5.606
5.290
5.511
5.606
* In 15C5 1-3 centre-centre O-O distance has been considered
Section-2
Interaction energy parameters
Table.S5. Calculated binding energy and thermodynamic parameters of different crown ether-Sr2+ ion system at BP86/TZVP level of theory in gas phase.
Ligand Binding energy(kcal/mol)
Binding enthalpy(kcal/mol)
∆Scal/mol/k
Binding free energy(kcal/mol)
Without ZPE With ZPE
12C4 -148.86 -146.60 -147.19 -42.65 -134.47
15C5 -180.08 -177.14 -177.73 -35.35 -167.19
18C6 -200.25 -196.46 -197.05, -199.00*,-208.00**
-36.28 -186.23
DB18C6 -192.72 -190.30 -190.89 -33.25 -180.97
Aza-DB18C6 -193.90 -190.54 -191.13 -39.12 -179.46
* Reference [44] calculated at RHF/6-31G* level of theory** Reference [44] calculated at MP2/6-31G* level of theory
Table.S6. Complexation energy of Sr(NO3)2 with different crown ethers at BP86/TZVP level of theory in gas and solvent phase.
Ligand Ecomp (kcal/mol)
(gas) (water) (chloroform) (Nitrobenzene)
Sr(NO3)2 -433.05 -35.26 -145.42 -50.72
12C4- Sr(NO3)2 -464.12 -49.03 -166.84 -65.05
15C5- Sr(NO3)2 -474.73 -59.80 -178.05 -75.79
18C6 -Sr(NO3)2 -483.28 -67.82 -185.55 -84.04
DB18C6 -Sr(NO3)2 -475.09 -56.68 -174.64 -75.15
Table.S7. Calculated structural parameters of complexes of DB18C6 with different metal ions at BP86/TZVP level of theory.
System Bond distance (Å)(gas)
M-L-NO3 complex
C-C C-O C-O* M-O O-O (transannular
distance)
M-O
Be2+ 1.522, 1.518, 1.525, 1.524
1.447, 1.463, 1.466, 1.467
1.406, 1.417, 1.457, 1.468, 1.419, 1.399, 1.447, 1.476
1.888, 1.924, 1.910, 1.869, 1.785, 1.861
2.785,2.731,3.646
1.556, 1.747, 1.758, 1.691
Mg2+ 1.521, 1.523, 1.523, 1.506
1.461, 1.457, 1.457, 1.459
1.403, 1.419, 1.449, 1.475, 1.417, 1.469, 1.402, 1.451
2.135, 2.126, 2.137, 2.134, 2.134, 2.125
3.437,3.475,4.248
2.159, 2.242, 2.185, 2.187,2.371, 2.623, 2.475, 2.491
Ca2+ 1.504, 1.518, 1.513, 1.516
1.450, 1.450, 1.453, 1.454
1.401, 1.415, 1.468, 1.452, 1.402, 1.403,
1.453, 1.454
2.427, 2.383, 2.489, 2.406, 2.423, 2.427
4.381,4.647,4.908
2.463, 2.469, 2.470, 2.457,2.698, 2.582, 2.583, 2.726, 2.689, 2.730
Sr2+ 1.511, 1.5121.507, 1.517
1.463, 1.4511.452, 1.453
1.403, 1.412, 1.402, 1.403, 1.450, 1.4501.449, 1.452
2.576, 2.559, 2.605, 2.5572.595, 2.566
4.823,5.113,5.166,
2.621, 2.632, 2.623, 2.632,2.690, 2.665, 2.726, 2.741, 2.733, 2.752
Ba2+ 1.509, 1.509, 1.510, 1.514
1.450, 1.452, 1.452, 1.458
1.401, 1.401, 1.401, 1.410, 1.449, 1.449, 1.450, 1.459
2.708, 2.7682.767, 2.754, 2.742, 2.745
4.937,5.368,5.422
2.776, 2.780, 2.792, 2.808, 2.771, 2.805, 2.831, 2.802, 2.809, 2.819
H3O+ 1.510, 1.5091.510, 1.519
1.446, 1.444, 1.428, 1.429
1.393, 1.374, 1.373, 1.404, 1.444, 1.424, 1.459. 1.435
2.636, 2.866, 2.640, 3.03, 2.822, 2.589
4.966,5.360,5.312
2.583, 2.981, 2.937, 3.212, 3.822, 3.460, 3.183
Na+ 1.506, 1.521, 1.512, 1.511
1.435, 1.435, 1.437, 1.437
1.396, 1.450, 1.381, 1.438, 1.434, 1.380, 1.381, 1.434
2.543, 2.5432.567, 2.493, 2.600, 2.547
4.869,5.142,4.925
2.378, 2.381, 2.526, 2.763, 2.838, 2.785, 2.856, 2.719
*adjacent to benzo ring
Bold: O between two methylene carbons; italics: O of nitrate anion
Table.S8. Calculated NBO charge on free crown ethers and its metal ion complexes at BP86/TZVP level of theory.
Free
Ligand NBO charge
O (gas) water CHCl3 NB
12C4 -0.483, -0.467, -0.476, -0.491
-0.513, -0.500, -0.508, -0.503
-0.503, -0.489, -0.489, -0.500
-0.512, -0.499, -0.507, -0.503
15C5 -0.463, -0.467, -0.473, -0.467,
-0.466
-0.498, -0.501, -0.488, -0.500,
-0.496
-0.486, -0.489, -0.484, -0.489,
-0.486
-0.496, -0.500, -0.488, -0.499,
-0.495
18C6 -0.467, -0.472, -0.460, -0.467, -0.464, -0.464
-0.485, -0.496, -0.496, -0.484, -0.496, -0.496
-0.476, -0.487, -0.488, -0.476, -0.487, -0.488
-0.483, -0.495, -0.495, -0.483, -0.495, -0.495
DB18C6 -0.408, -0.465, -0.410, -0.415, -0.458, -0.409
-0.427, -0.491, -0.428, -0.432, -0.428, -0.487
-0.421, -0.483, -0.422, -0.426, -0.478, -0.421
-0.427, -0.491, -0.429, -0.432, -0.488, -0.428
Aza-DB18C6 -0.589, -0.619, -0.569, -0.607, -0.614, -0.568
-0.592, -0.629, -0.572, -0.616, -0.623, -0.568
-0.592, -0.625, -0.571, -0.613, -0.620, -0.568
-0.592, -0.628, -0.572, -0.616, -0.622, -0.568
Sr2+-complex
Ligand NBO
O water CHCl3 NB Sr(gas)
12C4 -0.596, -0.591, -0.591, -0.595
-0.578, -0.574, -0.574, -0.574
-0.588, -0.585, -0.586, -0.588
-0.585, -0.582, -0.583, -0.585
1.877
1.916(w)
1.909(NB)
1.901(ch)
15C5 -0.590, -0.589, -0.590, -0.585,
-0.590
-0.579, -0.572, -0.576, -0.570,
-0.578
-0.583, -0.577, -0.581, -0.574,
-0.583
-0.586, -0.581, -0.583, -0.577,
-0.582
1.865
1.890(w)
1.882(ch)
1.888(nb)
18C6 -0.582, -0.585, -0.575, -0.579,
-0.572, -0.575, -0.566, -0.571,
-0.575, -0.578, -0.569, -0.574,
-0.572, -0.575, -0.566, -0.572,
1.864,
-0.578, -0.576 -0.571, -0.566 -0.573, -0.570 -0.571, -0.567 1.881(w)
1.876(ch)
1.881(nb)
DB18C6 -0.541, -0.582, -0.546, -0.557, -0.576, -0.573
-0.520, -0.575, -0.524, -0.536, -0.570, -0.555
-0.527, -0.578, -0.531, -0.543, -0.572, -0.562
-0.520, -0.576, -0.525, -0.536, -0.570, -0.556
1.877,
1.890(ch)
1.896(water)
1.895(NB)
Aza-DB18C6 -0.667, -0.691, -0.692, -0.699, -0.688, -0.671
-0.657, -0.687, -0.686, -0.691, -0.686, -0.663
-0.661, -0.688, -0.689, -0.694, -0.687, -0.666
-0.657, -0.687, -0.687, -0.691, -0.687, -0.664
1.802
1.818(ch)
1.824 (water)
1.824(nb)
Table.S9. Calculated values of HOMO-LUMO energy gap of different free crown ethers at BP86/TZVP level of theory.
Ligand HOMO-LUMO gap (eV)
(gas) (water) (Chloroform) (Nitrobenzene)
12C4 6.24 6.48 6.42 6.49
15C5 6.03 6.29 6.21 6.28
18C6 6.09 6.09 6.04 6.08
DB18C6 4.01 4.09 4.05 4.08
aza-DB18C6 3.12 3.27 3.22 3.26
Table.S10. Calculated Structural parameters of CSCDCH and CSCDTBDCH at BP86/TZVP level of theory.
Ligand Bond distance(Å)
C-C C-O O-O
CSCDCH 1.513, 1.513, 1.517, 1.516
1.428, 1.423, 1.427, 1.430, 1.420, 1.419, 1.419, 1.420, 1.423, 1.421, 1.421, 1.422
5.503**, 5.787, 6.035
CSCDTBDCH 1.514, 1.514, 1.516, 1.526
1.424, 1.432, 1.431, 1.423, 1.429, 1.422, 1.416, 1.421, 1.423, 1.421, 1.415, 1.419
4.658**, 6.399, 5.992
** between two methylene O atom
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.
