A Structural Study of Triboluminescence TL

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Certain physical properties associated with
certain space groups or point groups        
Piezoelectricity is the property of a crystal to
develop an electric charge when subjected to
pressure or tension in certain directions and is
observed in crystals with polar axes. o      
Applications of piezoelectricity include (but are
not limited to) quartz timepieces and
microphones triboluminescence.later
          Optical activity refers to the
ability of crystals to rotate plane-polarized
light.           Pyroelectricity is the property
of a crystal to develop electrical polarization
when the temperature is changed and can only
occur in non-centrosymmetric crystal systems.
           Ferroelectricity (important in
electro-ceramics) also shows polarization for a
temperature change but has the additional feature
of changing the direction of polarization in an
electric field.   See Table below for a listing
of the point groups that exhibit the
above-mentioned properties
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Literature case studies

• TRIBOLUMINESCENCE
• Non-centric space groups
• Conducting materials
• Segregated 1-D stacks
• Magnetic materials
• Integrated 1-D stacks
• Photoluminescent materials
• Packing by closed-shell metal-metal interactions

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A Structural Study of Triboluminescence (TL)

• General
• Almost exclusively seen in crystalline samples
• Luminescent species
• the surrounding gas (N2)
• the compound itself
• a combination of both

TL spectrum of sucrose
Energy level of N2
emission
excitation
piezoelectricity
Noncentrosymmetric space group
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• Zinks golden rule
• only noncentrosymmetric crystals could be
  triboluminescent.
• ? See ABSTRACT TABLE 1 IN HANDOUT
• B. P. Chandra, J. I. Zink, Inorg. Chem., 1980,
  19, 3098.
• Some other papers by Professor Zink about
  triboluminescence
• Zink, J. Hardy, G. E. Sutton, J. E., J. Phys.
  Chem., 1976, 80, No.3, 248.
•  G. E. Hardy J. I. Zink, Inorg. Chem., 1976, 15,
  3061.
•  B. P. Chandra, J. I. Zink, J. Phys. Chem., 1982,
  86, 4138

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Zinks Rule is Valid for 11 Tetrahedral Mn(II)
Complexes
Cotton, F. A. Daniels, L. M. Huang, P. Inorg.
Chem. 2001, 40, 3576.
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SECOND HANDOUT Refutation of a Claimed Exception
to Zinks Rule (TEA)Eu(DBM)4
redetermine
I2/a Z 4
Ia Z 4 R1 0.0581 wR2 0.0952 Flack x
0.00(2)
R(F) 0.0749 R(wF) 0.0817
Cotton, F. A. Daniels, L. M. Huang, P. Inorg.
Chem. Comm., 2001, 4, 319.
Sweeting, L. M. Rheingold, A. L. J. Am. Chem.
Soc., 1987, 109, 2652.
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Three Genuine Exceptions to Zinks Rule
Structural Redeterminations
(piperidinium)Eu(BA)4
Tb(antipyrine)6I3
TbCl2(H2O)6Cl P2/n Z 2 R1
0.0147 wR2 0.0317
R Z 3
P21/n Z 4
R1 0.0253 WR2 0.0601
R1 0.0573 WR2 0.0887
Rheingold, A. L. King, W., Inorg. Chem., 1989,
28, 1715.
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Not Every Noncentrosymmetric Eu(III) Complexes
Are Observably Triboluminescent
Not Triboluminescent
Eu2(phen)2(C8H7O2)6 2H2O
Na3Eu(ODA)38H2O
Cc Z 4 R1 0.0547 WR2 0.1214
Cc Z 4 R1 0.0255 WR2 0.0699
Albin, M. Whittle, R. R. Horrocks, W. D.
Inorg. Chem. 1985, 24, 4591.
Jin, L.-P. Wang, R.-F. Chem. J. Chin. Univ.
1993, 14, 1195.