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Novel photonic materials Manthos G. Papadopoulos Institute of Organic and Pharmaceutical Chemistry. National Hellenic Research Foundation 48 Vas. Constantinou Av. Athens 11635. We will consider a series of derivatives, which have interesting linear and nonlinear optical properties - PowerPoint PPT Presentation
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Novel photonic materialsNovel photonic materials
Manthos G. PapadopoulosManthos G. Papadopoulos
Institute of Organic and Pharmaceutical Chemistry.Institute of Organic and Pharmaceutical Chemistry.National Hellenic Research FoundationNational Hellenic Research Foundation
48 Vas. Constantinou Av.48 Vas. Constantinou Av.Athens 11635Athens 11635
We will consider a series of derivatives,
which have interesting
linear and nonlinear optical properties
and possible applications
in the photonic industry
Unifying features of this work:
•Molecules with large NLO properties
and how these can be interpreted
•Discovery of mechanisms in order
to modify the L&NLO properties
More specifically, we shall comment on the results of three projects:
1. The L&NLO properties of derivatives involving noble gas atoms
2. The L&NLO properties of [60]fullerene derivatives
3. The structure and properties of Ni-dithiolenes
Definition of the electric properties E = E(0) -μαFα - (1/2)ααβFαFβ - (1/6)βαβγFαFβFγ
- (1/24)γαβγδFαFβFγFδ - ...
μα : Dipole moment
ααβ: Polarizability
βαβγ: First hyperpolarizability
γαβγδ: Second hyperpolarizability
Why the L&NLO properties are important: Theory
Study of L&NLO processes (e.g. Kerr effect) Intermolecular interactions
Applications Design and study of NLO materials (optical processing of information, optical computing)
Noble gas derivatives
Definition of the project:
We consider insertion of a noble gas atom, Ng, in the chemical bond A-B, leading to A-Ng-B.
Specific examples we will consider involve insertion of:
Ar in HF leading to HArF
Xe in HCnH leading to HXeCnH
Xe in AuF lading to AuXeF
Why are the noble gas derivatives interesting and significant?
It is amazing what a noble gas atom, in the middle of a single bond can do, for example it leads to:
large NLO properties,
significant charge transfer etc
Which is the expanation?
HArF
A. Avramopoulos, H. Reis, J. Li and M. G. Papadopoulos, J. Am. Chem. Soc., 126, 6179 (2004).
Properties of noble gases
Synthesis of HArFa (argon fluoro-hydride)[first covalent neutral cond. argon der.]
photolysis of HF in solid argon matrix
Point of interest:
The effect of Ar on the NLO properties of the resulting derivative
a. L. Khriachtchev et al., Nature, 406, 874 (2000)
μz
αzz
βzzz
PolHFMP2CCSD(T) aug-cc-pV5ZHFMP2
3.1392.6912.578
3.0852.653
37.61 55.3759.80
37.8054.01
-597.8-1220.9-1418.1
-578.7-1102.5
The dipole moment, polarizability and
first hyperpolarizability of HArF (in a.u.)
Rationalization of βzzz
μgg: ground state dipole momentμee: excited state dipole momentμge: transition dipole momentΕge: transition energy
2)geE(
2)ge)(ggee(3)0(
μgg: 3.473/0.745 a.u.μee: -0.814/-0.907 a.u.μge: 1.419/-0.611a.u.Εge: 0.276/0.570 a.u.Method: HF/Pol, CIS/Pol
All the above properties contribute so that βzzz of HArF is much larger than that of HF
Comparison of HArF with HF
HArF βzzz=-561.5 a.u. HF/Pol -340.7 a.u. TSM
HF βzzz=-7.4 a.u. HF/Pol -5.7 a.u. TSM
Reliabity of TSM
Reliability of TSM
Large effect of Ar
HF…Ar van der Waals complex
μz=0.983 a.u. (3.473 a.u.)
αzz=19.11 a.u. (34.25 a.u.)
βzzz = -35.09 a.u. (-561.5 a.u.) ratio=16
Charge of Ar: 0.02 (0.56) ratio=28
Method: HF/Pol
Comparison of HArF with
C6H6
Αzz = 44.74 a.u. (34.25 a.u.)
Method: MP4[SDQ]
P-nitro-aniline
βzzz = 797.5 a.u. ( -561.5 a.u.)
Method: HF/Pol
The linear and nonlinear optical
properties of derivatives with inserted
Xe
The first Xe derivative was reported by Bartlet in 1962[Proc. Chem. Soc., 218(1962)]
A large number of Xe compounds have been reported since then
HXeF, AuXeF, XeAuF
F. Holka,A. Avramopoulos, O. Loboda, V. Kellö, M. G. Papadopoulos,Chem. Phys. Letters, 472, 185 (2009)
Points of interest:Points of interest:
•Effect of Xe
•Comparison of H with Au
HXeF, AuXeF: not synthesized yet
XeAuF: several NgMF have been synthesized
Ng: Ar, Kr, XeM: Cu, Ag, AuX: F, Cl, Br
Bonding:
Xe - Au bond: covalent [1]
Au - Xe [AuXeF] bond: partially covalent
(AXe)+ F- : significant charge transfer A= H, Au
1. S. A. Cook and M. C. L. Gerry, J. Am Chem. Soc. 126, 17000 (2004).
The barrier height
AuXeF: 119 kJmol-1
separates the global minimum (AuF+Xe) from the local minimum
AuXeF XeAuF
Xe 0.498 0.159
Au 0.377 0.650
F -0.876 -0.810
NBO charges
Similar charges on F
Quite different charges for Xe of XeAuF and AuXeF
Method: HF/aug-cc-pVQZ
μz αzz βzzz
HXeF 2.019 59.7 -571
AuXeF 2.243 184.3 -2441
XeAuF 2.612 76.4 -265
L&NLO properties
Method: CCSD(T)Basis set: aug-cc-pVQZECP: Au(60), Xe(28)
The position of Xe has a great effect on αzz and βzzz
βzzz (AuXeF) / βzzz (AuF) = 6.0
βzzz (XeAuF) / βzzz (AuF) = 0.7
βzzz (HXeF) / βzzz (HF) = 57.0
Method: CCSD(T)Basis set: aug-cc-pVQZ
Xe may greatly affect βzzz
NR R
μz 3.675 2.047
αzz 211.52 188.06
βzzz -13520 -1826
Relativistic contribution: AuXeF
Methods: CCSD(T), Douglas-KrollBasis sets: PolX, PolX_DK
βzzz = great effect of relativistic contribution
Novel compounds derived by
Xe inserted into HC2H and HC4H:
L&NLO properties
A.Avramopoulos, L. Serrano-Andres, J. Li, H. Reis and M. G. Papadopoulos, J. Chem. Phys., 127, 214 (2007).
Preparation
HXeC2H and HXeC2XeH:They are prepared in a low-temperature Xe matrix using UV photolysis of C2H2 and subsequently annealing at 40-45K[JACS, 125, 4696 (2003)]
HXeC4H:Tanskanen et al. reported its preparation
[JACS, 125, 16361 (2003)]
HC2XeC2H:
Ansbacher et al. predicted that the diacetylide Xe exists as a metastable chemically-bound compound[PCCP, 8, 4175 (2006)]
Structures Weight (%)a
H–Xe+C–CH (I) 44
H·Xe·CCH (II) 26
H–Xe+–CCH (III) 14
H–Xe2+C–CH (IV) 11
H+XeC–CH (V) 5
Method:CASVB(6,4)/3-21G*
Resonance structures of HXeC2H
Charge transfer in HXeC2H
Intra-molecular
Inter-molecular
NBO Charge Distribution
•1 and 2 Xe atoms:Approx. the same charge
•The chain length does not appear to have an effect
Method:HF/aug-cc-pVZ
•1 Xe atomEnd:0.79 eMiddle:1.02 e
•3 Xe atoms:The middle one has much larger charge
Inter-molecular charge transfer{Xe matrix}/HXeC2H
Two models(a) 6 Xe atoms octahedrally placed around HXeC2HA1A2=7.56 a.u.A2A3=9.45 a.u.Method:MP2/aug-cc-pVDZ
(b) 8 Xe atoms arranged in a cube A1A2=15.12 a.u.
NBO analysis:
insignificant CT takes place from the Xe environment to HXeC2H:
0.02e in the first model and
0.002e in the second model
HXeC2H
HC2H
Method:CCSD(T)/B1
The effect of Xe
Is significant
HXeC2XeHHXeC2H
Method: MP2/B1
The effect of1 and 2
Xe atoms
H2C2H
H2C4H
Δγzzzz = 30 000 au (approx.)
H2XeC2H
H2XeC4H
Δγzzzz = 340 000 au (approx.)
The effect of Xein connection with effect
of the chain length
H-Xe-CC-CC-H γzzzz =111 190 a.u
H-CC-Xe-CC-H γzzzz =28 488 a.u.
H-CC-CC-H γzzzz = 31 224 a.u.
Xe leads to a reduction of γzzzz !
The position of Xe has a significant effect on γzzzz
Method: MP2/aug-cc-pVDZ
Decomposition channels of HXeC2H
H+ Xe + C2H
HXeC2H
Xe + HC2H
34 kcalmol-1
104 kcalmol-1
The barrier to this exothermic reaction is very high, 64.6 kcalmol-1
and prevents the molecule from dissociation
T. Ansbacher et al., PCCP, 8, 4175 (2006)
Vibrational properties
Example: HXeC2H
αpvzz = [μ2](0,0) = 60.13 a.u
Vibrational Modes:
H-Xe: 1681cm-1 [μ2](0,0) = 13.1 a.uXe-C: 313 cm-1 [μ2](0,0) = 46.8 a.u
The other modes have a negligible contribution (0.23 a.u.)
Method:MP2/aug-cc-pVDZ
βpvzzz = [μα](0,0) = -835 a.u.
Vibrational Modes:
H-Xe: 1681cm-1 [μα](0,0) = 1212 a.uXe-C: 313 cm-1 [μα](0,0) = -2079 a.u
The other modes have a very small contribution (32 a.u.)
Method:MP2/aug-cc-pVDZ
Local field effect
The Xe derivatives have been synthesized in a Xe matrix
Thus it would be useful to compute the effect of the Xe environment on the L&NLO properties
Example: HXeC2H
The discrete local field approximation has been applied
Only the dipole and induced dipole interactions between HXeC2H and the Xe environment are considered
Local field expression:
,
][)( ',')11(,'
'
1cell0 kkkkk
N
kkk FLVF
Where
N is the number of molecules in the cell
Vcell is the volume of the cell
ε0 is the permitivity of vacuum
α,β,γ are the Cartesian components
Fk’α is the permanent local field effect on molecule k’ due to the surrounding molecules
μk’β is the dipole moment of the free molecule k’
αk’αβ is the polarizability of the free molecule k’
L(11) is the Lorentz-factor tensor
Model:
Cubic closed packed with dimensions a=b=c=24.8092 ÅIt involves 255 Xe atoms
H Xe C C H
Y
Z
X
Employed data:
HXeC2H: Dipole moment and polarizability of at the CCSD(T) level and
Xe: experimental polarizability value (27.10 au)
Results:
Local field: Fz=-4.4x10-3 au
μz: 50.5%αzz: 2.5%βzzz: 20.2%γzzzz: 12.7%
Changes of properties
Interpretation of the results
Insertion of Xe in HCnH leads to a large increase of γzzzz
For example:
γzzzz(HXeC2H)=38740 au γzzzz(HC2H)=3380 au
Ratio=11.5
Why?
Method: CASSCF/CASPT2Basis set:ANO-RCCXe:7s6p4d2f1gC:4s3p2d1fH:3s2p1dCASSSF(10,14)
The computations have shown that insertion of Xe leads to:
(a) Excited states of lower energy
(b) An electronic spectrum which is more dense in low lying states
(c) Many non-zero contributions to the transition dipole moment matrix
The NLO properties are:
proportional to products of TDM matrix elements and
inversely proportional to products of energy differences
Therefore an enhancement to NLO properties is expected
The SOS model
SOS computed properties
HC2H HXeC2H
αzz = 11.07 au αzz = 26.51 au
γzzzz = 3473 au γzzzz = 9102 au
The SOS model reflects the expected trend
On the electronic structure of H-Ng-Ng-F
(Ng=Ar, Kr, Xe) and the L&NLO properties
of HXe2F
A.Avramopoulos, L. Serrano-Andre, J.Li, M. G. Papadopoulos, J. Chem. Theory Comput. 6, 3365 (2010).
Questions:
The diradical character of HNg2F
and the L&NLO properties
Methods:
CASVB, MS-CASPT2, CCSD(T)
Electronic ground state description
HArArF: 38% σ2 + 56% σσ*HΚrΚrF: 53% σ2 + 39% σσ*HΧeXeF: 58% σ2 + 35% σσ*
Increase of the closed shell character:
Xe > Kr > Ar
Method: MS-CASPT2/ANO
CASVB computations show:
The total weight of the resonance structureswith diradical character is approx.:
99% for HArArF
97% for HKrKrF
87% for HXeXeF
The singlet-triplet (3Σ+) gap (STG)
provides an indication for the diradical
character of the system:
STG
HAr2F 4.7 kcal/mol
HKr2F 14.7 kcal/mol
HXe2F 28.7 kcal/mol)
Wirz suggested that a diradical is a molecule with
STG which does not differ by much more than
≈ 2kcal/mol.
The expression “diradicaloid”
would then extend this range to ≈ 24 kcal/mol.
So, all the HNg2F are diradicaloids.
HF HXeF HXe2F
μz 0.703 1.975 3.788
αzz 6.19 59.59 420.4
βzzz -11.5 -582.1 -11040
γzzzz x 10-3 0.284 22.7 -4000
Method: CCSD(T)/aug-cc-pVDZ
Stability, Electronic Structure
and L&NLO Properties of
HXeOXeF and FXeOXeF
A.Avramopoulos, J. Li, G. Frenking, M. G. Papadopoulos, J. Phys. Chem. A, 115, 10226 (2011)
HXeOXeF (FXeOXeF) results
from introduction of 2 Xe atoms
in HOF (FOF)
We have shown that the novel derivatives
HXeOXeF and FXeOXeF
can be synthesized, because they are
protected by high energy barriers
VB orbitals of HXeOXeF
CASPT2/ANOCCSD/aug-cc-pVDZMP2/aug-cc-pVDZ
Description of the ground state
HXeXeF 58.0% σ2 + 35% σσ*
HXeΟXeH 77.0% σ2 + 9% σσ*
FXeΟXeF 76.5% σ2 + 10% σσ*
Insertion of O increasesthe closed character
E1 = 14.9E2 = 25.5E3 = 90.3
Units: kcal/mol
Dissociation paths of HXeOXeF calculated at the CASPT2/ANO level.
E4 = 50.1 kcal/molE5 = 31.9 kcal/molE6 = 20.1 kcal/mol
Method: CASPT2/ANOZPE has been taken into accountReactants and products were connected through Intrinsic Reaction Coordinate (IRC) calculations
HOXeF is another novel derivative
HXeOXeF is a local minimum and is higher in energy
than several of its dissociation products:
E(HXeOXeF) – E(HOF + 2Xe) = 125.4 kcal/mol
E(HXeOXeF) – E(HO + F + 2Xe) = 85.2 kcal/mol
E(HXeOXeF) – E(OF + H + 2Xe) = 9.0 kcal/mol
HXeOXeF: Metastable
E1= 49.5 kcal/mol E2= 40.5 kcal/mol E3= 32.1 kcal/mol
Dissociation paths of FXeOXeF calculated at the CASPT2/ANO level
E4 = 30.1 kcal/molE5 = 13.2 kcal/molE6 = 11.1 kcal/mol
Frenking et al. [1] found that HArArF and HKrKrFare associated with low-energy barriers.Thus, they can NOT be observed.
But,HXeXeF 13.1 kcal/molHXeOXeF 14.9 kcal/molFXeOXeF 40.5 kcal/mol
Thus O and F increase the barrier and thusFArOArF and FKrOKrF may be observed.
G. Frenking et al., Angew. Chem. Int. Edition, 48, 366 (2009).
HXeXeFa HXeOXeF HXeOXeH FXeOXeF
μz3.788 2.747 0.987 0.623
αzz420.4 92.8 107.3 90.5
βzzz-11040 -1720 -49 -89.0
Method: CCD(T)/aug-cc-pVTZa. aug-cc-pVDZ
L&NLO Properties
Insertion of O reduces the L&NLO properties
The L&NLO properties of some
Ni-Dithiolene derivatives
Luis Serrano-Andrés, A. Avramopoulos, J. Li, P. Labéquerie, D. Begué,V. Kellö, M. G. Papadopoulos, J. Chem Phys., 131, 134312 (2009).
Points of interest:
• The low-lying excited states of NiBDT
• The impressive NLO properties and their interpretation
a 11Ag [71% ()2()
0−21% ()0()
2].b The energy difference is within the method accuracy. For simplicity
the 11Ag state will be considered the ground state at this level.c 11B1u state 65% [(π 2)
1(π 3)1].
d 13B1u state 92% [(π 2)1(π 3)
1].
State ΔE/eV Main configuration
11Ag ( diradicaloid)a −0.004b … (π2)2(π3)
0 - (π2)0(π3)
2
11B1u (*)c
0.000b … (π2)
1 (π3)1
. . 14 states .
31B3u (σSNi ππ π *) 3.064 … (σSNi)1 (π 1)
1 (π 2)2 (π 3)
2
13B1u (diradical)d 0.612 … (π 2)1 (π 3)
1
Excited states structure of Ni(SExcited states structure of Ni(S22CC22HH22))22
Basis set: ANO-RCCBasis set: ANO-RCC
Method: CASSCF/CASPT2Method: CASSCF/CASPT2
Remarks:
The main findings of the CASSCF/CASPT2 computations are:
The quasidegenaracy of 11Ag and 11B1u and the large number of low lying excited states.
These features are very likely to lead to large NLO properties
Table 4. A Basis set study of NiBDTa. The UBHandBHLYP functional was employed. All values are in au.
PropertyBasis set
αzz γzzzzx10-4
6-311G* 222.0 68.1
SDD[Ni]/6-31G*
221.9 55.8
ZPolX 245.3 67.7
aug-cc-pVDZ 244.7 71.9
aug-cc-pVTZ 245.2 68.0
aug-cc-pVQZ 245.4 67.6
a The B3LYP/SDD optimized geometry was employed to all calculations.
Properties of Ni(SProperties of Ni(S22CC22HH22))22
Method: UBHandHLYPMethod: UBHandHLYP
PropertyMethod
αzz γzzzzx10-4
UBHandHLYP 245.3 67.7
UCCSD 300.5 72.4
UCCSD(T) 364.3 119.0
CASSCF/CASPT2m/a1b1b2a2
b
12/4242 (42,4*2*) 67.9/282.2 1647.5/216.0
16/4444 (44,4*4*) 243.2/340.7 1102.7/184.7
20/4646 (46,4*6*) 309.3/363.8 869.5/153.1
a The properties were computed numerically. Base field: 0.005 au. b m: Number of active electrons; a1b1b2a2: Number of orbitals
in subspaces of C2v symmetry.
Basis set: ZPolXBasis set: ZPolX
Method: UBHandHLYP/
6-31G*
Main points
The big second hyperpolarizability of NiBDT has been interpreted in terms of the quasidegeneracy of the 11Ag and 11B1u states.As well as the many low lying excited states.
The considered Ni-dithiolene derivatives havevery big NLO properties.
The L&NLO properties of [60]fullerene
derivatives
O. Loboda, R. Zalesny, A. Avramopoulos, J. –M. Luis, B. Kirtman, N. Tagmatarchis, H. Reis and M. G. Papadopoulos, J. Phys. Chem. A, 113, 1159 (2009).
Points of interest:
Selection of the appropriate method (e.g. functional)
Computation of the electronic and vibrational contributions
Selection of functional groups
OvershootingEffect:3-55 larger
Comment: The substituents were selected according to increasing Hammett σp constant, which may be used as a measure of their electron donating capabilities. Methods: BLYP and HF(it does not have the overshoot problem).
Ratio:2
Remark:The ratio of the BLYP and the HF values increases monotonically and becomesquite large for the strongest donors.
Ratio:41
Concluding remarks
Mechanisms which lead to large NLO properties have been discussed
Novel derivatives with possible photonic applications have been proposed
Acknowledgement
Colleagues who contributed to this work:
Dr Aggelos Avramopoulos, NHRF, GreeceDr Heribert Reis, NHRF, GreeceDr Luis Serrano Andrés, Universitat de València, SpainDr Jiabo Li, SciNet Technologies, USADr Robert Zalesny, NHRF, GreeceDr Oleksandr Loboda, NHRF, GreeceProfessor B. Kirtman, University of California, USADr Josep Maria Luis, University of Girona, SpainDr Nikos Tagmatarchis, NHRF, GreeceProfessor Vladimir Kellö, Comenius University, Slovakia