γ butyrolactone Dimers and Trimers 69 th annual international symposium on molecular spectroscopy Eric Willis Chris Baumann June 19 2014 RI07 Optimized Structure of γ butyrolactone ID: 265348
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Slide1
Infrared Spectra and Calculated Binding Energies of γ-butyrolactone Dimers and Trimers
69
th
annual international symposium on molecular spectroscopy
Eric
Willis
, Chris Baumann
June 19,
2014
RI07Slide2
Optimized Structure of γ-butyrolactone
UM06/6-311++(2d,p)
Bond lengths (Å)
R12 = 1.189, R62 = 1.353, R56 = 1.426Angles (°)∠123 = 128.6, ∠126 = 122.6, ∠623 = 108.8, ∠562 = 110.7Dihedral Angles (°)∠1234 = 162.8, ∠1265 = 177.2Slide3
αβ DimerSlide4
αγ DimerSlide5
βγ DimerSlide6
γγ DimerSlide7
Dimer Structural ChangesElongation of C=O bond observed in all species
C
γ
– O bond elongated in all speciesCarbonyl C-O bond shortened in case of γγ and βγ dimersSeveral bond angle alterations observed in dimersCentered around carbonyl group and ring oxygenDihedral angle changes indicating changes in ring puckeringIncreased puckering on one side, decreased on the otherSlide8
αγγ Ring TrimerSlide9
αβαγ Stacked Trimer
Changes magnified in middle unit
Dihedral angles almost unchanged throughout the molecule.Slide10
The Covalent TrimerSlide11
Energy Information
Species
Energy (kJ/mol)
Binding Energy (kJ/mol)Counterpoise Correction (kJ/mol)Monomer-804239.19----αβ Dimer
-1608419.54
58.85
3.60
αγ Dimer
-1608420.78
57.60
3.50
βγ Dimer
-1608420.64
57.74
3.03
γγ Dimer
-1608423.14
55.25
3.29
α
γ
γ
Ring Trimer
-2412648.76
68.81
6.46
αβαγ Stacked Trimer
-2412643.50
74.08
7.36
Covalent Trimer
-2412488.73
228.85
--Slide12
Matrix Isolation ProcessGBL deposited on nitrogen at 20 K
Cooled down to 12 K
Photolysis
AnnealingSlide13
Monomer SpectrumSlide14
Dimer SpectraSlide15
αγγ SpectrumSlide16
αβαγ Stacked TrimerSlide17
Comparison with Experimental Spectrum (13 K)Slide18
Carbonyl Region Close-upSlide19
Pre-AnnealingSlide20
Post-AnnealingSlide21
Results of Experimental Spectral AnalysisDimer and trimer peaks can be differentiated, however individual dimer and trimer structures can’t be resolved
Relative amount of dimer and trimer increases with annealing
Photolysis affects ratio as wellSlide22
Deuterated DifficultiesSlide23
Anharmonic Corrections
Type of Transition
Frequency (cm
-1)Intensity (km mol-1)Overtone (v17)1847.560.0Combination Band (v20 + v12)
1869.8
63.5
Combination Band (v20 + v13)
1866.3
18.3
Combination Band (v21 + v11)
1851.8
13.8
Combination Band (v23 + v10)
1868.1
14.6
Combination Band (v25 + v8)
1856.6
70.5
Several combinations and overtones in this region can contribute to the messiness in the carbonyl region for the deuterated spectrumSlide24
Electronic Spectroscopy
Excited State
State
Energy (eV)Wavelength (nm)Oscillator StrengthS213.000-A5.4293
228.36
0
2
2
1.000-A
5.7507
215.6
0.0008
0
3
3.000-A
5.8472
212.04
0
2
4
1.000-A
5.898
210.22
0.0023
0
5
3.000-A
6.0806
203.9
0
2
6
3.000-A
6.3386
195.6
0
2
Monomer
Excited State
State
Energy (ev)
Wavelength (nm)
Oscillator Strength
S
2
1
3.000-A
5.4822
226.16
0
2
2
3.000-A5.5095225.040231.000-A5.8072213.50.0004041.000-A5.8294212.690.0007053.000-A6.0303205.60263.000-A6.0476205.010271.000-A6.0691204.290.0028081.000-A6.0924203.510.0022093.000-A6.0983203.3102103.000-A6.1157202.7302113.000-A6.267197.8402121.000-A6.2915197.070.00040
αβ Dimer
Excited StateStateEnergy (ev)Wavelength (nm)Oscillator StrengthS213.000-A5.5058225.190223.000-A5.5268224.330231.000-A5.8378212.380.0002041.000-A5.8604211.560.0004053.000-A6.0253205.770263.000-A6.0566204.710271.000-A6.0573204.680.0024081.000-A6.0905203.570.0017093.000-A6.1194202.6102103.000-A6.1556201.4202113.000-A6.2555198.202121.000-A6.2705197.730.00180
αγ
DimerSlide25
Excited State
State
Energy (ev)
Wavelength (nm)Oscillator StrengthS213.000-A5.4865
225.98
0
2
2
3.000-A
5.4911
225.79
0
2
3
1.000-A
5.8171
213.14
0.0004
0
4
1.000-A
5.8251
212.84
0.0005
0
5
3.000-A
6.0585
204.65
0
2
6
3.000-A
6.0623
204.52
0
2
7
3.000-A
6.0807
203.9
0
2
8
3.000-A
6.09
203.59
0
2
9
1.000-A
6.0985
203.30.00070101.000-A6.1254202.410.00420113.000-A6.2771197.5202121.000-A6.2893197.130.00140βγ DimerExcited StateStateEnergy (ev)Wavelength (nm)Oscillator StrengthS213.000-A5.4809226.210223.000-A5.4838226.090231.000-A5.8117213.330041.000-A5.8218212.970.0008053.000-A6.0329205.510263.000-A6.056204.73027
3.000-A
6.0871203.680283.000-A6.10762030291.000-A6.1182202.650.00030101.000-A6.145201.770.00450113.000-A6.322196.1202121.000-A6.3361195.680.00270γγ DimerExcited StateStateEnergy (ev)Wavelength (nm)Oscillator StrengthS213.000-A5.5602222.990223.000-A5.5687222.650233.000-A5.5771222.310241.000-A5.8732211.10.0009051.000-A5.87612110.0017061.000-A5.8883210.560.0012073.000-A
5.9723
207.6
0
2
8
3.000-A5.9775207.420293.000-A6.0071206.402101.000-A6.0122206.220.00150111.000-A6.0239205.820.00250121.000-A6.0529204.840.00480133.000-A6.1121202.8502143.000-A6.1197202.602153.000-A6.1422201.8602163.000-A6.2356198.8302173.000-A6.2446198.5502181.000-A6.2504198.360.00250
αγγ
TrimerSlide26
Excited State
State
Energy (ev)
Wavelength (nm)Oscillator StrengthS213.000-A5.4822
226.16
0
2
2
3.000-A
5.4857
226.02
0
2
3
3.000-A
5.5916
221.73
0
2
4
1.000-A
5.804
213.62
0.0005
0
5
1.000-A
5.8105
213.38
0.0003
0
6
1.000-A
5.9208
209.4
0.0003
0
7
3.000-A
5.9597
208.04
0
2
8
3.000-A
5.9775
207.42
0
2
9
1.000-A
5.9918
206.920.00230103.000-A6.0047206.4802111.000-A6.0179206.030.00180121.000-A6.0309205.580.00240133.000-A6.09203.5902143.000-A6.1112202.8802153.000-A6.175200.7902163.000-A6.2673197.8302171.000-A6.2782197.480.00070183.000-A6.2895197.1302αβαγ TrimerExcited StateStateEnergy (ev)Wavelength (nm)Oscillator StrengthS21
3.000-A
5.6354220.010223.000-A5.6367219.960231.000-A5.663218.940.0006041.000-A5.6642218.890.0006053.000-A5.8073213.50261.000-A5.8387212.350.0036073.000-A5.8994210.170281.000-A5.9248209.260.0011093.000-A5.9379208.802103.000-A5.9387208.7702111.000-A5.955208.20.00080121.000-A5.9558208.170.00080133.000-A6.0737204.1302143.000-A6.0742204.11
0
2
15
1.000-A
6.1008
203.220.00260161.000-A6.1016203.20.00260173.000-A6.2411198.6602183.000-A6.2415198.6502Covalent TrimerSlide27
Summary/Conclusions Structural changes observed in monomer units when dimer and trimer species are formed
Dimers and trimers can be detected experimentally using vibrational spectroscopy
However, individual dimer and trimer species cannot be resolved
Complicated nature of carbonyl region may be due to combination bands and overtonesSlide28
What’s Next?GBL + H
2
O complexes
Selective photodissociation of trimers and dimers as a possibilityMore accurate calculationsCreating more trimer structures and higher multimers