MINISTRYOF EDUCATIONANDTRAINING
QUYNHONUNIVERSITY

PHANDANGCAMTU

STUDY ON STABILITY AND NATURE OF
INTERACTIONSOFFUNCTIONALORGANICMOLECULESWITH
CO2AND H 2O
BYUSINGQUANTUMCHEMICALMETHOD

DOCTORALDISSERTATION

BINHDINH-2022


MINISTRYOF EDUCATIONANDTRAINING
QUYNHONUNIVERSITY

PHANDANGCAMTU

STUDY ON STABILITY AND NATURE OF
INTERACTIONSOFFUNCTIONALORGANICMOLECULESWITH
CO2ANDH2O
BYUSINGQUANTUMCHEMICALMETHOD
Major: Theoretical and Physical
ChemistryCodeNo.:9440119

Reviewer 1: Assoc. Prof. Dr. Tran Van
ManReviewer 2: Assoc. Prof. Dr. Ngo Tuan
CuongReviewer3:Dr.NguyenMinh Tam
Supervisor:Assoc.Prof.Dr.NGUYENTIEN TRUNG

DECLARATION
Thisd i s s e r t a t i o n w a s d o n e a t t h e L a b o r a t o r y o f C o m p u t a t i o n a l C h e m
i s t r y andModelling(LCCM), Quy NhonUniversity, Binh Dinh province, under thesupervision
of Assoc. Prof. Dr. Nguyen Tien Trung. I hereby declare that the resultspresentedarenewandoriginal.
Most of them were published in peer-reviewedjournals. For using results from joint papers, I have gotten
permissions from my co-authors.
BinhDinh,2022
Supervisor

Ph.D.Student

Assoc.Prof.Dr.NguyenTienTrung

PhanDangCamTu


ACKNOWLEDGEMENT
To all the family members, teachers, and friends, I would not complete
thisdissertationwithout their helpandsupport.
First, I am kindly thankful to my supervisor, Assoc. Prof. Dr. Nguyen
TienTrungforhisadviceandencouragementduringmyPhDlife.Ialsoexpressthanksto
Assoc.Prof.Dr.VuThiNganandProf.MinhThoNguyenfortheirvaluableadviceanddiscussing some researchproblems.
I am thankful to all the past and present members of the LCCM lab
foroutgoingactivitiesandvaluablediscussionsduringmyresearchtime.Itisa pleasure for me to
thankmy

seniors,HoQuoc


Dai

and

Nguyen

Ngoc

Tri

formorningcoffeechattingandsolvingallthetechnicalproblems.Igratefullyacknowledgethelect
uresoftheDepartmentofChemistry,FacultyofNaturalSciences,andthestaffintheOfficeofPostgr
aduateManagement,QuyNhonUniversity.
IsincerelythanktotheVietnamNationalFoundationforScienceandTechnologyDevelop
ment(NAFOSTED)undergrantnumber104.062017.11;DomesticPhDScholarshipProgrammeofVingroupInnovationF o u n d a t i o n (VinIF),
Vietnam; and the VLIR-TEAM project awarded to Quy Nhon UniversitywithGrantnumber ZEIN2016PR431(20162020)forthefinancialsupport.
I heartily thankmy long-time friends, Nhung and Nga, who alwaysa r e b y my side
and share with me all the difficulties in life. Thanks should also go to TranQuang Tue for
helping me understand some mathematical aspects in the study ofquantum chemistry; and
to Nguyen Duy Phi, who encouraged me in the first twoyearsofmyPhD.
Last but most important, words are never enough to express my gratitude tomy
parents. To dad, the first person I asked for the decision of doing PhD and themost
influential person in my life, I wish you were here, at this moment and proudlysmilingtoyour
daughter.Tomom,withyourloveandendlesspatience,youmakemefeel stronger andreadytoovercome allchallenges.


TABLEOFCONTENTS
Listofsymbolsandnotations...............................................................................i
Listoffigures.....................................................................................................ii
Listoftables......................................................................................................iv

GENERALINTRODUCTION.......................................................................1
1. Researchintroduction.................................................................................1
2. Objectandscopeof the research...................................................................2
3. Noveltyandscientificsignificance...............................................................2
Chapter1.DISSERTATIONOVERVIEW.....................................................4
1.1. Overviewoftheresearch...........................................................................4
1.2. Objectivesoftheresearch.......................................................................11
1.3. Researchcontent....................................................................................11
1.4. Researchmethodology..........................................................................12
Chapter 2. THEORETICAL BACKGROUNDS
ANDCOMPUTATIONALMETHODS....................................................................14
2.1. Theoreticalbackgroundofcomputationalchemistry................................14
2.1.1. TheHartree–Fockmethod...............................................................14
2.1.2. Thepost–Hartree-Fockmethod........................................................17
2.1.3. Densityfunctionaltheory.................................................................21
2.1.4. Basisset..........................................................................................23
2.2. Computationalapproachestononcovalentinteractions.............................25
2.2.1. Interactionenergy..........................................................................25
2.2.2. Cooperativiveenergy......................................................................26
2.2.3. Basissetsuperpositionerror............................................................26
2.2.5.Naturalbondorbitaltheory...............................................................27
2.2.4.Atomsinmoleculestheory.................................................................30
2.2.6. Noncovalentindex..........................................................................33
2.2.7. Symmetry-adaptedperturbationtheory............................................35
2.3. Noncovalentinteractions.......................................................................37


2.3.1. Tetrelbond.....................................................................................38
2.3.2. Hydrogenbond...............................................................................39
2.3.3. Halogenbond.................................................................................41

2.3.4. Chalcogenbond..............................................................................43
2.4. Computationalmethods oftheresearch...................................................44
Chapter3.RESULTSANDDISCUSSION.....................................................46
3.1. InteractionsofdimethylsulfoxidewithnCO2a n d

n H 2O(n=1-2).46

3.1.1. Geometries, AIM analysis and stability of
intermolecularcomplexes........................................................................46
3.1.2. Interactionandcooperativeenergiesandenergycomponent..............50
3.1.3. BondingvibrationalmodesandNBOanalysis...................................54
3.1.4. Remarks.........................................................................................59
3.2. Interactionsofacetone/thioacetonewithnCO2a n d nH2O...........................60
3.2.1. Geometricstructures......................................................................60
3.2.2. Stabilityandcooperativity...............................................................62
3.2.3. NBOanalysis,andhydrogenbonds...................................................70
3.2.4. Remarks.........................................................................................72
3.3. Interactionsofmethanolwith CO2a n d H2O...............................................73
3.3.1. StructuresandAIManalysis.............................................................73
3.3.2. Interactionandcooperativeenergies................................................76
3.3.3. VibrationalandNBOanalyses.........................................................78
3.3.4. Remarks.........................................................................................79
3.4. InteractionsofethanethiolwithCO2a n d H2O.............................................80
3.4.1. Structure,stabilityandcooperativity................................................80
3.4.2. VibrationalandNBOanalyses.........................................................84
3.4.3. Remarks.........................................................................................88
3.5. Interactions of CH3OCHX2with nCO2and nH2O (X=H, F, Cl,
Br,CH3;n=1-2).............................................................................................88
3.5.1. Interactionsof CH3OCHX2with1CO2(X=H,F,Cl,Br, CH3).............88
3.5.2. InteractionsofCH3OCHX2with2CO2(X =H, F,Cl, Br,CH3)..............95



3.5.3. Interactions ofCH3OCHX2with nH2O (X = H, F, Cl, Br, CH3;n=12)
98
3.5.4. Interactions of CH3OCHX2with 1CO2and 1H2O (X =H, F, Cl,
Br,CH3)..................................................................................................102
3.5.5. Remarks.......................................................................................107
3.6. InteractionsofdimethylsulfidewithnCO2( n = 1 - 2 ) ...................................108
3.6.1. GeometricstructuresandAIManalysis...........................................108
3.6.2. Interactionandcooperativityenergyandenergeticcomponents
...............................................................................................................110
3.6.3.

VibrationalandNBOanalyses...........................................112

3.6.4.

Remarks..........................................................................115

3.7. GrowthpatternoftheC2H5OH∙∙∙nCO2c o m p l e x e s

( n = 1 - 5 ) .........................115

3.7.1. StructuralpatternoftheC2H5OH∙∙∙nCO2complexes(n=1-5)............115
3.7.2. Complex stability, and changes of OH stretching frequency
andintensityundervariationofCO2molecules..........................................119
3.7.3. Intermolecularinteractionanalysis................................................123
3.7.4. Roleofphysicalenergeticcomponents............................................127
3.7.5. Remarks.......................................................................................129
CONCLUSIONS.........................................................................................130

FUTUREDIRECTIONS.............................................................................132
LIST OF PUBLICATIONS CONTRIBUTING TO THEDISSERTATION.....133
REFERENCES............................................................................................135


Listofsymbolsandnotations
AIM
aco
acs
BCP
BSHB
BSSE
ChB
CCSD(T)
DME
DMSO
DMS
DPE
EDT
Eint
Ecoop
HF
HB
MEP
MP2
NBO
NCIplot
PA
RSHB
SAPT

TtB
ZPE
(r)
2ρ(r)
H(r)
E(2)
Lp

AtomsinMolecules
Acetone
Thioacetone
Bondcriticalpoint
Blue-shiftinghydrogenbond
Basissetsuperposition error
Chalcogenbond
Coupled-clustersinglesanddoublesmethods
Dimethylether
Dimethylsulfoxide
Dimethylsulfide
Deprotonationenergy
Electrondensitytransfer
Interactionenergy
Cooperativeenergy
HartreeFockmethod
Hydrogenbond
Molecularelectrostaticpotential
Second-orderMoller-Plessetperturbation method
Naturalbondorbital
NoncovalentInteractionplot
Protonaffinity

Red-shiftinghydrogen bond
Symmetry-adaptedperturbationtheory
Tetrelbond
Zero-point vibrational energy
Electrondensity
Laplacianofelectrondensity
Totalenergydensity
Second-orderenergyofintermolecularinteraction
Lonepair

1


Listoffigures
Figure1.1.
Figure1.2.
Figure2.1.
Figure2.2.
Figure2.3.

Figure2.4.
Figure2.5.
Figure2.6.

Figure2.7.
Figure3.1.

Figure3.2.
Figure3.3.


Figure3.4.

Figure3.5.

Figure3.6.

Figure3.7.

Threetypes of CO2complexes
Stablegeometriesofcomplexesinvolving CO2
TheflowchartillustratingHartree–Fockmethod
Plotsof GTOandSTObasisfunctions
Perturbativedonoracceptori n t e r a c t i o n , i n v o l v i n g a f i l l e d
orbitalandanunfilledorbital*
Theseparationbetweentwoatomicbasinsin HF molecule
Molecularg r a p h o f H 2O,e t h a n e , c y c l o p r o p a n e a n d c u b
a n e atMP2/6-311++G(d,p)
a) Representativebehaviour ofatomicdensity
b) Appearanceo f a s ( )s i n g u l a r i t y w h e n t w o a t o m i c
densitiesapproacheachother
Differencei n g e o m e t r y o f c o m p l e x e s C O 2HCla n d C O 2-HBrobtainedfromexperimentalspectroscopy
Geometrieso f s t a b l e c o m p l e x e s f o r m e d b y i n t e r a c t i
onsof
DMSOwithCO2andH2O
AlinearcorrelationbetweenindividualE HBa n d ρ(r)val
uesatBCPs
Stablestructureso f c o m p l e x e s
formedbyinteractions of
(CH3)2CZw ithC O 2a n d H 2O(Z=O , S)
(the va lues in parenthesesareforcomplexesof(CH3)2CS)

The correlation in interaction energies of the most
energetically favorable structures in six systems
atCCSD(T)/6-311++G(2d,2p)//MP2/6-311++G(2d,2p)
SAPT2+ decompositions of the most stable complexes
intophysicallyenergeticterms:electrostatic(Elst),exchange(E
xch),induction(Ind)anddispersion(Disp)ataug-ccpVDZbasisset
Stableg e o m e t r i e s o f c o m p l e x e s f o r m e d b y i n t e
ractionof
CH3OHwithCO2and H 2OatMP2/6-311++G(2d,2p)
Stableg e o m e t r i e s o f c o m p l e x e s f o r m e d b y i n t e r a c t
ionsof

Page
7
7
16
23
30

31
32
34

38
47

49
60

64


68

74

81


Figure3.8.
Figure3.9.

C2H5SHwithCO2and H 2OatMP2/6-311++G(2d,2p)
Stable structures of CH3OCHX2∙∙∙1CO2 complexes
atMP2/6-311++G(2d,2p)
Thedifferenceininteractionenergies(withZPEandBSSE)

89
91


Figure3.10.
Figure3.11.

Figure3.12.
Figure3.13.
Figure3.14.
Figure3.15a.
Figure3.15b.
Figure3.16.
Figure3.17.


Figure3.18.

Figure3.19.

ofCH3OCHX2∙∙∙1CO2complexes
Contributions(%)ofphysicalenergeticterms
Stables t r u c t u r e s a n d t o p o l o g i c a l g e o m e t r i e s o f c o
mplexes
CH3OCHX2∙∙∙2CO2
ThestablestructuresofCH 3OCHX2∙∙∙nH2Ocomplexes(n=
1-2;X=H,F,Cl,Br,CH3)
StablestructuresofcomplexesC H 3OCHX2∙∙∙1CO2∙∙∙1H2O(X
=H,F,Cl,Br,CH3)
Optimizedstructuresandtopologicalgeometriesof(CH 3)2S
andnCO2(n=1,2)at MP2/6-311++G(2d,2p)
OptimizedstructuresofC2H5OH∙∙∙nCO2(n=1-2)
OptimizedstructuresofC2H5OH∙∙∙nCO2(n=3-5)
Thebindingenergiespercarbondioxide
NCIploto f t e t r e l m o d e l a n d h y d r o g e n m o d e l w i t h g r a d i
ent
isosurfaceofs=0.65
MEPsurfaceo f m o n o m e r s i n c l u d i n g C 2H5OH( a
ntia n d
gauche)andCO2atMP2/aug-cc-pVTZ
Contributions( % ) o f differente n e r g e t i c c o m p o n e n t
sinto
stabilization energy of C2H5OH∙∙∙nCO2 complexes
atMP2/aug-cc-pVDZ


92
96

99
103
108
116
118
123
124

127

128


Listoftables
Table2.1.
Table3.1.

Table3.2.

Table3.3a.
Table3.3b.

Table3.3c.

Table3.4.

Table3.5a.

Table3.5b.

Table3.6.

Table3.7.

Table3.8.

Table3.9.

Page
Characteristicsofthecommon NBOtypes
29
Interactione ne rgy (E)andcooperativity energy(E coop)ofbinar
51
y
and
ternary
systems
at
CCSD(T)/6311++G(2d,2p)//MP2/6-311++G(2d,2p)
Thes e c o n d 54
(2)
o r d e r p e r t u r b a t i o n e n e r g y ( E ,k J . m o l
1
,M P 2 / 6 - 311+
+G(2d,2p))fortransfersinheterodimersandheterotrimers
frominteractionsofDMSOwithCO2and H 2O
SelectedresultsofvibrationalandNBOanalysesforinteraction
56

of DMSOwithnCO2(n=1-2)(MP2/6-311++G(2d,2p))
Selectedr e s u lt s o f v i b r a t i o n a l a n d N B O a n a l y s 57
es(MP2/6311++G(2d,2p))forinteractionofDMSO withnH2O(n=1-2)
Selectedr e s u l t s o f v i b r a t i o n a l a n d N B O a n a l y
58
ses(MP2/6311++G(2d,2p))forinteractionofDMSO withCO2andH2O
Interactionenergya n d c o o p e r a t i v e e n e r g y o f c o m 63
plexesof
aco/acs and 1,2CO2 and/or 1,2H2O at CCSD(T)/6311++G(2d,2p)//MP2/6-311++G(2d,2p)
Concise summary of interactions between some organic
66
compoundsandCO2
Concises u m m a r y o f interactionso f o r g a n i c c o m p o u n d 67
sand
H2O(andCO2)
Changeso f b o n d l e n g t h ( r(X72
H),i n m Å ) a n d s t r e t c h i n g
frequency((X-H),incm -1)ofC -H andOHbonds involvedinhydrogenbond
Selectedp a r a m e t e r s a t t h e B C P s o f i n t e r m o l e c u l a r c o n t a c 75
tsin
complexeso f m e t h a n o l w i t h C O 2and/orH 2Oa t M P 2 / 6 - 311+
+G(2d,2p)
Interactionenergy andcooperativeenergy ofcomplexesformed
77
byi n t e r a c t i o n s b e t w e e n C H 3OHw i t h C O 2and/
orH 2Oa t CCSD(T)/6-311++G(2d,2p)//MP2/6-311++G(2d,2p)(kJ.mol-1)
Changeso f b o n d l e n g t h ( r)a n d c o r r e s p o n d i n 78
5



Table3.10.

gstretching
frequency()o f C ( O )
− H b o n d s i n v o l v e d i n H B s a l o n g w i t h selectedparametersatM
P2/6-311++G(2d,2p)
Interaction energy and cooperative energy of complexes
between C2H5SH and CO2 and/or H2O at CCSD(T)/6311++G(2d,2p)//MP2/6-311++G(2d,2p)

6

82


Table3.11.

Table3.12.

Table3.13.
Table3.14.
Table3.15.
Table3.16.
Table3.17.
Table3.18.

Table3.19.
Table3.20.

Table3.21.


Table3.22.
Table3.23.
Table3.24.

Table3.25.

Selectedp a r a m e t e r s a t t h e B C P s o f i n t e r m o l e c u l a r c o n t a c
tsof
complexesb e t w e e n C 2H5SHa n d C O 2a n d /
o r H 2Oa t M P 2 / 6 - 311++G(2d,2p)
EDTa n d E (2)o f i n t e r m o l e c u l a r i n t e r a c t i o
n s ofc o m p l e x e s
between C2H5SH and CO2 and/or H2O at MP2/6311++G(2d,2p)level
SelectedresultsofvibrationalandNBOanalysesforinteraction
of C2H5SHwithCO2andH2O
Intermoleculardistances(Å)ofCH3OCHX2∙∙∙1CO2complexes
Interaction energies corrected ZPE+BSSE of complexes
CH3OCHX2∙∙∙nCO2
Selected parameters (au) of
CH3OCHX2∙∙∙1CO2complexes(X=H,F,Cl,Br,CH3)
EDTandE(2)forCH 3OCHX2∙∙∙1CO2complexesatMP2/6- 311+
+G(2d,2p)leveloftheory
Interaction energy and cooperative energy of complexes
CH3OCHX2∙∙∙2CO2( X = H , F , C l , B r , C H 3)a t M P 2 / a u g c c - pVTZ//MP2/6-311++G(2d,2p)
EDTandE(2)forCH 3OCHX2∙∙∙2CO2complexesatMP2/6- 311+
+G(2d,2p)leveloftheory
Selectedp a r a m e t e r s a t B C P s t a k e n f r o m A I M r
es ults for
complexes of CH3OCHX2 with 1,2H2O at MP2/6311++G(2d,2p)
Interaction energy and cooperative energy of complexes

CH3OCHX2∙∙∙1,2H2O( X = H , F , C l , B r , C H 3)a t M P 2 / a u g - c c pVTZ//MP2/6-311++G(2d,2p)
Interaction energy and cooperative energy of complexes
CH3OCHX2∙∙∙1CO2∙∙∙1H2O(X=H,F, Cl,Br, CH3)
EDTandE(2)forCH 3OCHX2∙∙∙1CO2∙∙∙1H2O(X=H,F,Cl,Br,
CH3)atMP2/6-311++G(2d,2p)leveloftheory
ChangesofbondlengthC(O)
−H(inÅ)ands t r e t c h i n g frequency((C/O-H),incm-1)ofCHandOHb o n d s involvedi n H B o f c o m p l e x e s C H 3OCHX2∙∙∙1CO2∙∙∙
1H2O( X =
H,F,Cl, Br,CH3)
Selectedp a r a m e t e r s a t t h e B C P s o f i n t e r m o l e c u l a r c o n t a c

83

85

87
89
90
93
95
97

98
100

101

104
106
107


109


Table3.26.

tsof
(CH3)2S∙∙∙nCO2(n=1-2)
Interactione n e r gi e s a n d c o o p e r a t i v e e n e r g i e s o
fcomplexes
DMS∙∙∙nCO2

111


Table3.27.

Table3.28.

Table3.29.
Table3.30.

Table3.31.

Contributions of different energetic components into
stabilizatione n e r g y o f c o m p l e x e s D M S ∙ ∙ ∙ n C O 2usingS A P T
2 + approach
Selectedresultsofvibrational andNB Oanalysis o f complex
es
DMS∙∙∙nCO2atMP2/6-311++G(2d,2p)

RotationalconstantandvibrationalfrequenciesofOHgroupof
isolatedethanolandC2H5OH∙∙∙nCO2complexes
Binding energy of C2H5OH∙∙∙nCO2 complexes (n=15)calculatedatt h e M P 2 / a u g - c c - p V T Z / / M P 2 / 6 311++G(2d,2p)
leveloftheory
NBO analysis of C2H5OH∙∙∙nCO2 complexes (n=1-4) at
B97X-D/aug-cc-pVTZ

112

113

117
119

126


GENERALINTRODUCTION
1. Researchintroduction
Economic

development

and

industrialization

cause

a


significant

increase

inconcentration of gases emitted into the environment. Therefore, air pollution is oneof the
hottest topics which attracts a lot of attention. Increasing amount of carbon dioxide (CO2) in
the

air

is

the

main

factor

that

significantly

affects

the

greenhouseeffect.TheenhancingapplicationsofsupercriticalCO 2(hereafterdenotedb y scCO2) in
manufacturing


industries

help

to

partially

solve

emission

problems,

whilealsosaveotherresources.ScCO2hasattractedmuchattentionduetoitsenvironmentallyfriendly
applications,ascomparedtotoxicorganicsolvents. 1Compressed CO2h a s
used

as a

solvent

for

extraction

purposes

indeed


been

widely

or in organic solvent elimination/purification

processes, also as an antisolvent inpolymerization of some organic molecules and
precipitation of polymers. With theaim of finding the new materials and solvents which
preferred

CO2,

it

is

essential

toclarifyinteractionsbetweenCO2andfunctionalorganiccompoundsandtheirelectroniccharacter
isticsatmolecularlevel.Theseunderstandingsrequireasystematicstudy
combiningtheexperimentsandmodelling,andimportantly,aquantumcomputationalapproach.
Uptonow,variousexperimentalresearchesontheinteractionsbetween solutes
scCO2s o l v e n t

have

been

undertaken


to

better

and

investigate

the

s o l u b i l i t y inscCO2.Ingeneral,somefunctionalorganiccompoundsincludinghydroxyl,carbonyl,

thiocarbonyl,

carboxyl,

sulfonyl,

amine,

…

are

considered

as

CO 2-


philicones.Furthermore,theuseofpolarizedcompoundsasH2O,smalla l c o h o l s (CH3OH,
C2H5OH) as cosolvents was reported to affect the thermodynamic andeven kinetic
properties of reactions involving CO 2. Addition of H2O into scCO2solvent helps to increase the solubility
and extraction yield of organic compounds. Therefore,

CO2,

the systematic research on interactions between
H2O

and

organicfunctionalcompoundswillopenthedoorstothenatureandroleofformedinteractions,thee
ffectofcooperativityinthesolvent–cosolvent–solute system.
1


The achieved results are hopefully to provide a more comprehensive look at
scCO2applicationandalsoc ontribute tothe understanding o f the intrins ic cha ra c te ris tic
s ofweaknoncovalentinteractions.
2. Objectandscopeoftheresearch
- Research object: Geometrical structure, stability of complexes involving
CO2;natureandroleofnoncovalentinteractionsincludingtetrelbond, hydrogenbond.
- Scopes:complexesoffunctionalorganiccompoundsincludingdimethylsulfoxide,
acetone,

thioacetone,

methanol,


ethanol,

ethanethiol,

dimethyl

ether

and

itshalogen/methylsubstitution withsomemoleculesofCO2and/or H 2O.
3. Noveltyandscientificsignificance
This

work

representsthe

geometries,

stability,

properties

of

noncovalentinteractionsincomplexesofdimethylsulfoxide,acetone,thioacetone,d i m e t h y l
etheranditsdi-halogen/methylderivative,dimethylsulfide,methanol,ethanol, ethanethiol with CO2and/or
H2O.


Remarkably, general trend of complexes withmentioned organic compounds and

CO2and/or H2O is determined using high levelab initiocalculations. The bonding features of
complexes with CO2and/or H2O arealso analysed in detail. In addition, the effect of H 2O
presence leads to a significantincrease in stability and positive cooperativity as compared to
complexes containingonly CO2. The OH∙∙∙O HBs contribute largely into the cooperativity
among otherweakinteractionsincludingC∙∙∙O/STtBs,C−H∙∙∙OHBsandO∙∙∙OC h B s . Especially,itis
foundthegrowthpatternincomplexesofethanolwith1-5CO 2molecules which is expected to be useful for understanding the ethanol solvation
inscCO2.

It is important that the comparison of stability of complexes and strength

ofnoncovalentinteractionsarethoroughlyinvestigated.
Thesystematicallytheoreticalinvestigationoncomplexesb e t w e e n functional
organic molecules and a number of CO2and/or H2O ones could provideuseful information
for

the

development

of

promising

functionalized

materials

forCO2capture/sequestrationandincreaseknowledgeinnoncovalentinteractions.These o b t a i n e d r e

sultscanplayasthevaluablereferencesforfutureworkson


scCO2a n d benchmarkof noncovalentinteractions.
Thisdissertationisalsohopedtobeaneffectivereferenceforlectures,researchers,students,etcinstudying
about

computational

chemistry

molecularlevel,especiallynoncovalentinteractionsandcomplexesinvolvingCO2.

at


Chapter1.DISSERTATIONOVERVIEW
1.1. Overviewoftheresearch
Human emissions of CO2and other greenhouse gases are the primary driverof climate
change which is one of the present world’s most pressing challenges. Therelation between the
cumulative CO2emissions

and global temperature has been clearly

discovered.2It is said that CO2is the key

atmospheric gas that exerts controlover the strength of the greenhouse effect. Innovating the
use

of


CO2is

an

urgentmissionwiththeaimofdecreasingitsconcentrationinambientair.C

and

non-toxic,

and

it

reaches

a

O 2i s abundant, reusable

supercritical

point

at

an

easilycontrolledt e m p e r a t u r e a n d p r e s s u r e . S c C O 2is a w e l l k n o w n e f f e c t i v e s o l v e n t f o r thedevelopmentofgreenchemicalreactionsinsteadofconventionaltoxicorganicsolvents.

ScCO2is used in extensive applications in nanomaterials, food science, pharmaceuticals, especially in separation
and synthetic processes.3,4The effectiveuse of scCO2i n
o f s e p a r a t i o n h a s b e e n r e p o r t e d in

extraction and fractional processes

many previous works.3,5,6Nevertheless, the solvent has

drawbacks in solute polarorganic compounds and high molecular-mass ones. Thus, many
efforts

have

beenmadetofindouttheinteractingspeciesandeffectivethermodynamicreaction conditionsaimingto
enhancethesolubilityinscCO2.Fluorocarbons,fluoropolymers,andcarbonyl-basedcompoundsarepreviouslyconsideredas
CO2-philic functional groups.7,8,9While high cost and toxicity are the limitations of thefirst
two

compounds,

carbonyl-based

compounds

have

been

paid


much

attentionthankstotheirsimplesynthesisprocessandlowercost.Effortsforenhanced applicability
of

scCO2with

the

use

of

CO 2-philes

have

been

pursuedviaseries

ofexperimentalandtheoreticalworks.10,11,12,13,14,15
Dimethyls u l f o x i d e ( D M S O ) i s a c o m m o n s o l v e n t i n b
i o l o g i c a l a n d
physicochemicalstudies,whichiswidelyusedinsupercriticalantisolventprocesses, 16,17withman
yvaluableapplicationssuchasmicronizationofpharmaceuticalcompounds,polymers,catalysts,s