Synthesis and Crystal Structure of AgBr Nanoclusters in the Sodalite Cavities of K+-Exchanged Zeolite A (LTA)

Hyun Jung Kim, Seok Han Kim, Cheol Woong Kim, Ghyung Hwa Kim1 and Nam Ho Heo*

*Laboratory of Structural Chemistry, Department of Applied Chemistry Kyungpook National University, Daegu 702-701, Korea1Pohang Accelerator Laboratory, POSTECH, Pohang 790-784, Korea

Introduction

Various Properties ofVarious Properties of AgBr Nanoclusters in ZeolitesAgBr Nanoclusters in Zeolites A. Non-emissive indirect band gap materials (AgBr and Si) can become missive

when formulated as small clusters.a-f

B. The UV absorption band corresponding to the direct exciton absorption shifts

the blue as size decrease.g,h

C. The luminescence intensity arising from the direct recombination of exitons

increases with decreasing size in AgBr.h

D. The value of ionic conductivity of AgBr-montmorillonite higher than pure AgBr. i

a W.Chen, G.McLendon, A.Marchetti, J.M.Rhem, M.I.Freedhoff, C.Myers, J.Am.Chem.Soc. 1994 116 1585-1586 b M.I.Comor, J.M.Nedeljkovic, Chemical Physics Letters 1999 299 233-236 c L.E.Brus, P.F.Szajowski, W.L.Wilson, T.D.Harris, S.Schuppler, P.H.Citrin, J.Am.Chem.Soc. 1995 117 2915-2922 d K.P.Johansson, A.P.Marchetti, G.McLendon, J.Phys.Chem. 1992 96 2873 e L.Brus, J.Phys.Chem. 1994 98 3575 f W.L.Wilson, P.F.Szajowski, L.E.Brus, Science 1993 262 1242 g H.Zhang, M.Mostafavi, J.Phys.Chem. B 1997 101 8443-8448 h M.I.Freedhoff, A.P.Marchetti, G.McLendon, Journal of Luminescence 1996 70 400-413 i A.Robledo, N.J.Garcia, J.C.Bazan, Solid State Ionics 2001 139 303-308

Ag-ANa-A

0.05 M AgNO3 in CH3OH

K-A(AgBr)

Washing(CH3OH)

0.05 M KBrin CH3OH

By flow method for 2

days

Reaction with KBr in CH3OH for 2 days

Preparation of Preparation of K-A(0.5AgK-A(0.5Ag22BrBr22))(KBr)(KBr)

A. Preparation of Ag12-A & K-A(AgBr)

B. X-ray diffraction experiment

C. Structure determination of K-A(0.5Ag2Br2)(KBr)

Experiments

Table 1. Positional, Thermal, and Occupancy parameters Table 1. Positional, Thermal, and Occupancy parameters of of KK1212-A(0.5Ag-A(0.5Ag22BrBr22) (KBr)) (KBr)

1116(201)2702(21)2702(21)2702(21)8(g)K(1)

3269(947)5000e5000e3123(147)6(f)O(5)

2264(360)5000e 5000e 5000e 1(b)K(4)

1952(276)3678(36)3678(36)3678(36)8(g)Br(3)

1501(150)4269(29)4269(29)1268(38)24(m)K(3)

271(83)4228(23)4228(23)2624(33)24(m)O(4)

1030(102)5000e2715(24)2715(24)12(j)Br(2’)

1689(123)5000e3437(30)2143(33)24(l)Br(2)

1315(110)5000e2287(23)2287(23)12(j)Ag(2)

  5247(414)5000e4174(54)648(56)24(l)K(2)

  1384(134)1142(25)01142(25)12(i)Br(1)

  1054(57)968(10)968(10)968(10)8(g)Ag(1)

380(138)2414(20)2414(20)2414(20)8(g)K(1”)

382(29)2592(12)2592(12)2592(12)8(g)K(1’)

88(31)139(28)139(28)846(58)490(28)490(28)3442(7)1124(4)1124(4)24(m)O(3)

0084(38)382(31)382(31)541(55)2948(5)2948(5)012(i)O(2)

000402(57)540(66)1167(100)5000e-2247(9)012(h)O(1)

0031(10)176(16)212(16)207(16)3714(2)1829(2)024(k)(Si,Al)

U12U13U23U33U22U11 or Uisobzyx

WyckoffpositionAtoms

1.3(5)3

1.5(7)2

0.6(2)0.5

0.3(1)0.5

2.7(7)3

4.8(7)3

1.4(3)1

2.3(3)2

0.7(2)1

4.0(8)3

1.1(1)1

0.7(1)1

1.0(6)1

5.3(8)4

 24

 12

 12

 24d

variedfixed Occupancyc

Results & Discussion

X-ray diffraction experiment at 21X-ray diffraction experiment at 21CC

Structure determinationStructure determination

• Structure solution package : SHELX-97• Initial phasing with parameters of Na-Aa • Full-matrix least-squares refinement

X-ray source : PLS (Beamline 4A MXW of Pohang Light Source) Mo K radiation ( = 0.8265Å ) Space group of K-A(0.5Ag2Br2)(KBr) : Pm3m Cell parameter, a = 12.299(3) Å No. of reflections obsd. (Fo > 4(Fo)) : 368 Final error indices R1 = 0.082, R2 = 0.227

A. Ag2Br2 nanoclusters have been synthesized in a single crystal of Zeolite A

B. Structure determination

K12-A(0.5Ag2Br2 )(KBr) : Pm3m, a = 12.299(3) Å

R1 = 0.082 for the 368 reflections with Fo > 4(Fo)

C. Crystallographic characterization of Ag2Br2 nanoclusters

Ag–Br = 2.86(3) Å, Ag–Br–Ag = 92.2(15)º, Br-Ag-Br = 87.8(15)º

D. Ag2Br2 nanoclusters is stabilized by 10 strong interaction of Ag+ with 6-ring oxygens.

Ag(1)-O(3) = 3.06(2) Å

E. Half of all sodalite units of K12-A(0.5Ag2Br2 )(KBr) are filled with Ag2Br2 nanoclusters.

Conclusions

Stereoview of a large cavityStereoview of a large cavity in Kin K1212-A(0.5Ag-A(0.5Ag22BrBr22) (KBr)) (KBr)

Figure 2. A steroview of the large cavities (uc1 and uc2) in K-A(0.5Ag2Br2)(KBr). Ellipsoids of 20% probably are shown.

Angles

Distances

106.4(5) 110.6(4) 108.5(3) 112.2(5)  144.0(7) 158.8(7) 145.5(5)  88.4(11)93.9(7)103.0(11)86.9(12)

92.2(15)87.8(15)

102.7(16)

O(1)-(Si,Al)-O(2) O(1)-(Si,Al)-O(3) O(2)-(Si,Al)-O(3) O(3)-(Si,Al)-O(3)  (Si,Al)-O(1)-(Si,Al) (Si,Al)-O(2)-(Si,Al) (Si,Al)-O(3)-(Si,Al)  O(3)-K(1)-O(3) O(3)-K(1’)-O(3)O(3)-K(1”)-O(3)O(3)-Ag(2)-O(3)

Ag(1)-Br(1)-Ag(1) Br(1)-Ag(1)-Br(1) 

Br(2)-K(1)-Br(2’)

3.05(3)3.47(8)3.19(2)2.83(3)2.97(2)3.22(3)3.11(7)2.76(3)

2.66(5)2.85(5)2.61(7)3.10(6)3.21(17) 2.61(16)2.69(9)3.14(5)2.82(8)3.22(4)

136.6(13)111.8111.6175.4(18)89.9(2)170.2(19)105.8(19)103.1(18)

85.1(13)73.9(16)106.1(16)180.0(15)112.6(14)

85, 95

K(1)-Br(2)-K(1’)K(1)-Br(2)-K(2)K(1’)-Br(2)-K(2)K(1)-Br(2’)-K(1’)K(1)-Br(2’)-K(2)K(1)-Br(2’)-K(1”)K(1)-O(4)-K(2)K(1’)-O(4)-K(2)

O(4)-K(1’)-Br(2’)K(1”)-Br(3)-K(3)K(3)-Br(3)-K(4)K(1”)-Br(3)-K(4)K(3)-Br(3)-K(3)

O(4)-K(4)-O(4)

Br(2)-K(1)Br(2)-K(2)Br(2)-K(1’)Br(2’)-K(1)Br(2’)-K(1’)Br(2’)-K(1”)Br(2’)-K(2)Br(2’)-K(3)

K(1)-O(4)K(1’)-O(4)K(2)-O(4)K(3)-O(4)K(2)-O(5)K(3)-O(5)K(1”)-Br(3)K(3)-Br(3)K(4)-Br(3)K(4)-O(4)

1.664(4) 1.668(3) 1.665(3)   2.89(3) 2.76(2) 2.58(2) 3.06(2) 

2.50(7)3.05(4)3.07(3)2.78(5)

2.81(3)2.79(3)

2.86(3)

(Si,Al)-O(1) (Si,Al)-O(2) (Si,Al)-O(3)   K(1)-O(3) K(1’)-O(3) K(1”)-O(3) Ag(1)-O(3) 

K(2)-O(1)K(2)-O(2)K(3)-O(1)K(3)-O(2)

Ag(2)-O(1)Ag(2)-O(3)

Ag(1)-Br(1)

Table 2 . Selected Interatomic Distances (Table 2 . Selected Interatomic Distances (ÅÅ) and Angles ) and Angles (deg)(deg)

r (K+) = 1.33 Å r (Ag+) = 1.13 Å r (O2-) = 1.32 Å r (Br-) = 1.96 Å

Stereoview of a sodalite in KStereoview of a sodalite in K1212-A(0.5Ag-A(0.5Ag22BrBr22)(KBr))(KBr)

Figure 1. A steoreview of a sodalite unit of K-A(0.5Ag2Br2)(KBr) showing absorbed Ag2Br2 molecule. The Zeolite a framework is drawn with thick bonds between oxygens. Ellipsoids of 20% probably are shown.

Deviation In from the (111) plane at O(3)s of 6-ring1.72Å for K(1), 1.48Å for K(1’), 1.10Å for K(1”), -1.98Å for

Ag(1)