Catalytic transfer hydrogenation of maleic acid with stoichiometric amounts of formic acid in aqueous phase: Paving the way for more sustainable succinic acid production

Article abstract of DOI:10.1039/c9gc04221k

The aqueous phase hydrogenation of maleic acid (MAc) to succinic acid (SAc) is demonstrated in the absence of any organic solvent and using stoichiometric amount of formic acid (FAc) as source of H₂. Among the different noble metals (Pd, Au, Ru, Pt and Rh) and supports investigated (γ-Al₂O₃, TiO₂, CeO₂, ZrO₂, WO₃, CeZrO₄, carbon, nicanite, SiO₂ and TS-1), Pd/C was identified as the best catalyst. We observe that the undesirable formation of malic acid (MalAc) by hydration of MAc must be prevented. The transformation of MAc to SAc with negligible formation of MalAc is possible by using relatively mild temperature (140-150 °C) and a high catalyst to MAc ratio (i.e. fixed bed continuous flow reactor). Using the carboxylate forms (disodium maleate and sodium formate) instead of the acids results in an increase of the reaction rate. In a fixed bed reactor under a continuous flow of 15 wt% of MAc at a WHSV = 12 h^-1 (contact time = 5 min), at 150 °C, 10 bar of N₂ and using a formic acid/maleic acid molar ratio = 1, a yield of SAc close to 98% was obtained, equivalent to a productivity of 1.87 g SAc per g_cat per·h. Leaching of Pd was below 0.02 ppm. No deactivation was observed in long term experiments at 150 °C (ca. 730 h), although the characterization of the used catalyst by CO chemisorption and TEM and XPS studies showed certain sintering of Pd particles. Regarding the mechanism of the reaction, kinetic isotopic experiments using deuterated DCOOH indicated that the reaction must essentially proceed via catalytic transfer hydrogenation, formyl H of formic acid is involved in the rate determining step of the reaction. When using maleate and formate sodium salts, the second H needed for the reaction is supplied by the solvent (H₂O molecules). A preliminary environmental assessment (Life Cycle Analysis, LCA) of this CTH approach indicates that for relevant environmental categories of the LCA (such as climate change and consumption of fossil resources) the CTH process is greener than conventional hydrogenation process; the benefits are even larger if biomass-derived FAc is involved.

Full text of DOI:10.1039/c9gc04221k

View Article Online
View Journal
Green
Chemistry
Cutting-edge research for a greener sustainable future
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: M. López
Granados, J. Moreno, A. C. Alba Rubio, J. Iglesias, D. Martin Alonso and R. Mariscal, Green Chem., 2020,
DOI: 10.1039/C9GC04221K.
Volume 20
Number
May 2018
Pages 1919-2160
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
9
7
Green
Chemistry
Cutting-edge research for a greener sustainable future
rsc.li/greenchem
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 1463-9262
PAPER
Paul T. Anastas et al.
The Green ChemisTREE: 20 years after taking root with the 12
principles
rsc.li/greenchem

Page 1 of 14
&'()*( Gꢀ +r ,e ꢀe- n, C. ꢀ h) +e /m0 *i s. tꢀ 1r y)234-*
View Article Online
DOI: 10.1039/C9GC04221K
A !"#$%
!
"!#$"%&ꢀ"'!()*+'ꢀ,$-'./+(!"%.(ꢀ.*ꢀ0!#+%&ꢀ!&%-ꢀ1%",ꢀ
)
".%&,%.0+"'%&ꢀ!0.2(")ꢀ.*ꢀ*.'0%&ꢀ!&%-ꢀ%(ꢀ!32+.2)ꢀ4,!)+5ꢀ4!6%(/ꢀ
"
,+ꢀ1!$ꢀ*.'ꢀ0.'+ꢀ)2)"!%(!7#+ꢀ)2&&%(%&ꢀ!&%-ꢀ4'.-2&"%.(8
(5(46(+ꢀ77.8ꢀ9)-0)2:ꢀ;7<<=
A55(>.(+ꢀ77.8ꢀ9)-0)2:ꢀ;7<<
K)
L
5
L
+=(
)
GCꢀ$H>(IꢀJ2)-)+,* =ꢀ9CꢀG,2(-, =ꢀAC#CꢀA'L)M 0L4,=ꢀ9Cꢀ"3'(*4)* =ꢀ?CꢀG)2.N-ꢀA',-*, ꢀ)-+ꢀ CꢀG)24*5)'ꢀ
?@"ꢁꢀB7CB7DEF<7<<77777<
!
8(ꢀ)O0(,0*ꢀ>8)*(ꢀ8:+2,3(-).4,-ꢀ,Pꢀ1)'(45ꢀ)54+ꢀQGA5Rꢀ.,ꢀ*0554-45ꢀ)54+ꢀQSA5Rꢀ4*ꢀ+(1,-*.2).(+ꢀ4-ꢀ.8(ꢀ)L*(-5(ꢀ,Pꢀ)-:ꢀ,23)-45ꢀ
,'6(-.ꢀ)-+ꢀ0*4-3ꢀ*.,4584,1(.245ꢀ)1,0-.ꢀ,PꢀP,2145ꢀ)54+ꢀQTA5Rꢀ)*ꢀ*,025(ꢀ,PꢀUCꢀA1,-3ꢀ.8(ꢀ+4PP(2(-.ꢀ-,L'(ꢀ1(.)'*ꢀQ&+=ꢀA0=ꢀ 0=ꢀ
=ꢀ#(V2@=ꢀ#)2L,-=ꢀY45)-4.(=ꢀS4@ꢀ)-+ꢀ!SMBR=ꢀ&+F#ꢀZ)*ꢀ
*
;
&
.ꢀ)-+ꢀ 8Rꢀ)-+ꢀ*0>>,2.*ꢀ4-6(*.43).(+ꢀQ MA'
;
@
D
=ꢀ!4@
; ; ;
=ꢀ#(@=ꢀV2@=ꢀW@
D
X
;
4
+(-.4P4(+ꢀ)*ꢀ.8(ꢀL(*.ꢀ5).)':*.CꢀW(ꢀ,L*(26(ꢀ.8).ꢀ.8(ꢀ0-+(*42)L'(ꢀP,21).4,-ꢀ,Pꢀ1)'45ꢀ)54+ꢀQG)'A5RꢀL:ꢀ8:+2).4,-ꢀ,PꢀGA5ꢀ10*.ꢀ
L(ꢀ>2(6(-.(+Cꢀ!8(ꢀ.2)-*P,21).4,-ꢀ,PꢀGA5ꢀ.,ꢀSA5ꢀZ4.8ꢀ-(3'434L'(ꢀP,21).4,-ꢀ,PꢀG)'A5ꢀ4*ꢀ>,**4L'(ꢀL:ꢀ0*4-3ꢀ2(').46(':ꢀ14'+ꢀ
(1>(2).02(ꢀQBX7MB[7ꢀ\#Rꢀ)-+ꢀ)ꢀ8438ꢀ5).)':*.ꢀ.,ꢀGA5ꢀ2).4,ꢀQ4C(CꢀP4<(+ꢀL(+ꢀ5,-.4-0,0*ꢀP',Zꢀ2()5.,2RCꢀ]*4-3ꢀ.8(ꢀ5)2L,<:').(ꢀ
.
P,21*ꢀQ+4*,+401ꢀ1)'().(ꢀ)-+ꢀ*,+401ꢀP,21).(Rꢀ4-*.()+ꢀ,Pꢀ.8(ꢀ)54+*ꢀ2(*0'.*ꢀ4-ꢀ)-ꢀ4-52()*(ꢀ,Pꢀ.8(ꢀ2()5.4,-ꢀ2).(Cꢀ"-ꢀ)ꢀP4<(+ꢀL(+ꢀ
MB
2
()5.,2ꢀ0-+(2ꢀ)ꢀ5,-.4-0,0*ꢀP',Zꢀ,PꢀB[ꢀZ.Cꢀ^ꢀ,PꢀGA5ꢀ).ꢀ)ꢀWUS_ꢀ`ꢀB;ꢀ8 ꢀQ5,-.)5.ꢀ.41(ꢀ`ꢀ[ꢀ14-R=ꢀ).ꢀB[7ꢀ\#=ꢀB7ꢀL)2ꢀ,PꢀY
;
ꢀ)-+ꢀ
0*4-3ꢀ)ꢀP,2145ꢀ)54+F1)'(45ꢀ)54+ꢀ1,')2ꢀ2).4,ꢀ`ꢀB=ꢀ)ꢀ:4('+ꢀ,PꢀSA5ꢀ5',*(ꢀ.,ꢀEaꢀ^ꢀZ)*ꢀ,L.)4-(+=ꢀ(O046)'(-.ꢀ.,ꢀ)ꢀ>2,+05.464.:ꢀ,PꢀBCabꢀ
MB MB
3
ꢀSA5c35). c8 Cꢀ$()584-3ꢀ,Pꢀ&+ꢀZ)*ꢀL(',Zꢀ7C7;ꢀ>>1CꢀY,ꢀ+()5.46).4,-ꢀZ)*ꢀ,L*(26(+ꢀ4-ꢀ',-3ꢀ.(21ꢀ(<>(241(-.*ꢀ).ꢀB[7ꢀ\#ꢀQ5)Cꢀ
bD7ꢀ8R=ꢀ)'.8,038ꢀ.8(ꢀ58)2)5.(24I).4,-ꢀ,Pꢀ.8(ꢀ0*(+ꢀ5).)':*.ꢀL:ꢀ#@ꢀ58(14*,2>.4,-ꢀ)-+ꢀ!%Gꢀ)-+ꢀd&Sꢀ*.0+4(*ꢀ*8,Z(+ꢀ5(2.)4-ꢀ
4-.(24-3ꢀ,Pꢀ&+ꢀ>)2.45'(*Cꢀ (3)2+4-3ꢀ.8(ꢀ1(58)-4*1ꢀ,Pꢀ.8(ꢀ2()5.4,-=ꢀe4-(.45ꢀ4*,.,>45ꢀ(<>(241(-.*ꢀ0*4-3ꢀ+(0.(2).(+ꢀ?#@@Uꢀ
*
4
-+45).(+ꢀ.8).ꢀ.8(ꢀ2()5.4,-ꢀ10*.ꢀ(**(-.4)'':ꢀ>2,5((+ꢀ64)ꢀ5).)':.45ꢀ.2)-*P(2ꢀ8:+2,3(-).4,-=ꢀP,21:'ꢀUꢀ,PꢀP,2145ꢀ)54+ꢀ4*ꢀ4-6,'6(+ꢀ
-ꢀ.8(ꢀ2).(ꢀ+(.(214-4-3ꢀ*.(>ꢀ,Pꢀ.8(ꢀ2()5.4,-CꢀW8(-ꢀ0*4-3ꢀ1)'().(ꢀ)-+ꢀP,21).(ꢀ*,+401ꢀ*)'.*=ꢀ.8(ꢀ*(5,-+ꢀUꢀ-((+(+ꢀP,2ꢀ.8(ꢀ
4
2
()5.4,-ꢀ4*ꢀ*0>>'4(+ꢀL:ꢀ.8(ꢀ*,'6(-.ꢀQU
84*ꢀ#!Uꢀ)>>2,)58ꢀ4-+45).(*ꢀ.8).ꢀP,2ꢀ2('(6)-.ꢀꢀ(-642,-1(-.)'ꢀ5).(3,24(*ꢀ,Pꢀ.8(ꢀ$#AꢀQ*058ꢀ)*ꢀ5'41).(ꢀ58)-3(ꢀ)-+ꢀ5,-*01>.4,-ꢀ
PꢀP,**4'ꢀ2(*,025(*Rꢀ.8(ꢀ#!Uꢀ>2,5(**ꢀ4*ꢀ32((-(2ꢀꢀ.8)-ꢀ5,-6(-.4,-)'ꢀ8:+2,3(-).4,-ꢀ>2,5(**fꢀ.8(ꢀꢀL(-(P4.*ꢀ)2(ꢀ(6(-ꢀ')23(2ꢀ4Pꢀ
L4,1)**M+(246(+ꢀTA5ꢀ4*ꢀ4-6,'6(+C
;
@ꢀ1,'(50'(*RCꢀAꢀ>2('414-)2:ꢀ(-642,-1(-.)'ꢀ)**(**1(-.ꢀQ$4P(ꢀ#:5'(ꢀA-)':*4*=ꢀ$#ARꢀ,Pꢀ
.
,
-
01(2,0*ꢀ)>>'45).4,-*ꢀ)*ꢀ*,'6(-.*ꢀ)-+ꢀ)*ꢀ4-.(21(+4).(*ꢀ4-ꢀ.8(ꢀ
:-.8(*4*ꢀ,Pꢀ>8)21)5(0.45)'*=ꢀ)32,58(145)'*=ꢀ)-+ꢀ>,':1(2*C
-.4'ꢀP(Zꢀ:()2*ꢀ)3,=ꢀSA5ꢀZ)*ꢀ,-':ꢀ>2,+05(+ꢀP2,1ꢀ>(.2,58(145)'ꢀ
)'(45ꢀ)-8:+24+(Cꢀ!8(ꢀ>2,5(**ꢀ2(O042(*ꢀP42*.ꢀ.8(ꢀ'4O04+ꢀ>8)*(ꢀ
*
9("'.-2&"%.(
S0554-45ꢀ)54+ꢀQSA5Rꢀ)-+ꢀ4.*ꢀ+(8:+2).(+ꢀP,21=ꢀ*0554-45ꢀ)-8:+24+(=ꢀ
]
1
8
)6(ꢀ 10'.4>'(ꢀ )>>'45).4,-*ꢀ 4-ꢀ .8(ꢀ >8)21)5(0.45)'=ꢀ P,,+=ꢀ
8
:+2,3(-).4,-ꢀ,Pꢀ1)'(45ꢀ)-8:+24+(ꢀQB;7MBa7ꢀ\#=ꢀ7C[MXC7ꢀG&)=ꢀY4ꢀ
2ꢀ &+ꢀ 5).)':*.*Rꢀ 2(-+(24-3ꢀ *0554-45ꢀ )-8:+24+(ꢀ .8).ꢀ 4*ꢀ
+
(.(23(-.=ꢀ5,*1(.45=ꢀ.(<.4'(=ꢀ>8,.,32)>8:=ꢀ)32,58(145)'ꢀ)-+ꢀ
B ;
,
5
8(145)'ꢀ4-+0*.24(*ꢀ = Cꢀ&,':1(24I).4,-ꢀ,PꢀSA5ꢀZ4.8ꢀ+4)14-(*ꢀ,2ꢀ
;
[
*0L*(O0(-.':ꢀ8:+2).(+ꢀZ4.8ꢀ8,.ꢀZ).(2ꢀ.,ꢀ>2,+05(ꢀSA5ꢀ = Cꢀ
Z4.8ꢀ+4,'*ꢀ2(-+(2*ꢀ>,':)14+(*ꢀ,2ꢀ>,':(*.(2*ꢀZ4.8ꢀ4-.(2(*.4-3ꢀ
h
A-,.8(2ꢀ )'.(2-).46(ꢀ 2,0.(ꢀ 4*ꢀ .8(ꢀ >2,+05.4,-ꢀ ,Pꢀ *0554-45ꢀ
>
2,>(2.4(*=ꢀ *058ꢀ )*ꢀ 5,11(254)'':ꢀ )6)4')L'(ꢀ g4,-,''( ꢀ Q)ꢀ
,':L0.:'(-(ꢀ*0554-).(ML)*(+ꢀ>,':1(2RCꢀG,2(,6(2ꢀSA5ꢀ4*ꢀ)-ꢀ
)
-8:+24+(ꢀ)*ꢀ)ꢀL:M>2,+05.ꢀ,Pꢀ.8(ꢀ3)*ꢀ>8)*(ꢀ8:+2,3(-).4,-ꢀ,Pꢀ
)'(45ꢀ)-8:+24+(ꢀ.,ꢀJg$ꢀ)-+F,2ꢀB=XML0.)-(+4,'ꢀQB=XMg?@RCꢀ!8(ꢀ
0554-45ꢀ)-8:+24+(ꢀ5)-ꢀL(ꢀ2(5:5'(+ꢀL)5eꢀ.,ꢀ2()5.,2ꢀP,2ꢀ5,1>'(.(ꢀ
:+2,3(-).4,-ꢀ,2ꢀ*(>)2).(+ꢀ)-+ꢀ>024P4(+ꢀ;C
G,2(ꢀ 2(5(-.':=ꢀ P(21(-.).4,-ꢀ ,Pꢀ *03)2*ꢀ *((1*ꢀ .,ꢀ 3)4-ꢀ
>
1
4-.(21(+4).(ꢀ4-ꢀ.8(ꢀ>2,+05.4,-ꢀ,Pꢀ� ML0.:2,')5.,-(ꢀQJg$R=ꢀB=XM
*
L0.)-(+4,'ꢀQB=Xg?@R=ꢀ)-+ꢀ.(.2)8:+2,P02)-ꢀQ!UTRꢀP2,1ꢀ1)'(45ꢀ
D X
8
)54+ꢀQGA5Rꢀ = Cꢀ!8(*(ꢀ')..(2ꢀ5,1>,0-+*ꢀ5022(-.':ꢀP4-+ꢀ)'*,ꢀ
i b a E
5
,1>(.4.46(-(**ꢀ6(2*0*ꢀ.8(ꢀ>(.2,58(145)'ꢀ2,0.(ꢀ = = = Cꢀ!8(ꢀ
2,+05.4,-ꢀ,PꢀSA5ꢀP2,1ꢀL4,1)**ꢀP((+*.,5e*ꢀQ3'05,*(=ꢀ*.)258=ꢀ
':5(24-=ꢀ(.5Rꢀ2(O042(*ꢀ.8(ꢀ0.4'4I).4,-ꢀ,Pꢀ*0554-).(ꢀ>2,+05(2*ꢀ
>
3
i
ꢀ!"#ꢀ$%&'(ꢀ)#'*+ ,- ./0ꢀ!-0%12ꢀ -3ꢀ4506,*+%2ꢀ$%&'(78ꢀ9-*+,+'+0ꢀ&:ꢀ4 + /2*,*ꢀ -3ꢀ
1452,23)-4*1*ꢀ Cꢀ U,Z(6(2=ꢀ .8(ꢀ P(21(-.).4,-ꢀ >2,5(**ꢀ )'*,ꢀ
2(*(-.*ꢀ+2)ZL)5e*ꢀ.8).ꢀ.82().(-*ꢀ4.*ꢀ64)L4'4.:=ꢀ*058ꢀ)*=ꢀ.8(ꢀ
8)-+'4-3ꢀ,Pꢀ1452,,23)-4*1*=ꢀ.8(ꢀ>2(54*(ꢀ5,-.2,'ꢀ,Pꢀ.8(ꢀ>U=ꢀꢀ4.*ꢀ
,Zꢀꢀ>2,+05.464.:ꢀQP(21(-.).4,-ꢀ2(O042(*ꢀ',-3ꢀ2()5.4,-ꢀ.41(*Rꢀ
;
0+%&<506,*+%2ꢀ)4#9478ꢀ4=ꢀ> %,0ꢀ4'%,08ꢀ?8ꢀ?@ABCꢀ> 3%,3ꢀ)#( ,-7
4506,< /ꢀDꢀ!-E,%&-60-+ /ꢀ!-1,-00%,-1ꢀ$%&'(8ꢀF-,E0%*,3 3ꢀG02ꢀH' -ꢀ4 %/&*8ꢀ
=I'/,( -8ꢀ*=-8ꢀ>&*+&/0*8ꢀ> 3%,3ꢀ?@CJJ8ꢀ#( ,-
>
.ꢀ
4
<ꢀ
K0( %+60-+ꢀ&:ꢀ4506,< /ꢀ!-1,-00%,-18ꢀF-,E0%*,+2ꢀ&:ꢀI&/03&8ꢀI&/03&8ꢀLMꢀBJNAN8ꢀ
F-,+03ꢀ#+ +0*
$/'< -ꢀO,&%0-0P ./0*ꢀQQ48ꢀ> 3,*&-8ꢀR9ꢀSJTUC8ꢀF#ꢁV
K0( %+60-+ꢀ&:ꢀ4506,< /ꢀ -3ꢀO,&/&1,< /ꢀ!-1,-00%,-18ꢀF-,E0%*,+2ꢀ&:ꢀR,*<&-*,-W
'
3ꢀ
)-+ꢀ.8(ꢀ5,1>'(<ꢀ)-+ꢀ5,*.':ꢀ*(>)2).4,-M>024P45).4,-ꢀ*.(>*ꢀ,Pꢀ.8(ꢀ
*0554-45ꢀ)54+ꢀP2,1ꢀ.8(ꢀP(21(-.).4,-ꢀL2,.8ꢀB7Cꢀ
0ꢀ
>
3,*&-8ꢀUBUSꢀ!-1,-00%,-1ꢀK%,E08ꢀ> 3,*&-8ꢀR9ꢀSJTAN8ꢀF#ꢁ
jꢀ(M1)4'ꢁꢀ1'32)-)+,*k45>C5*45C(*ꢀ
'(5.2,-45ꢀS0>>'(1(-.)2:ꢀ"-P,21).4,-ꢀQ%S"Rꢀ)6)4')L'(ꢁꢀl+(.)4'*ꢀ,Pꢀ)-:ꢀ*0>>'(1(-.)2:ꢀ )-,.8(2ꢀ)'.(2-).46(ꢀ)-+ꢀ8438ꢀ:4('+*ꢀ8)6(ꢀL((-ꢀ2(>,2.(+ꢀQ4-ꢀ*,1(ꢀ
-P,21).4,-ꢀ)6)4')L'(ꢀ*8,0'+ꢀL(ꢀ4-5'0+(+ꢀ8(2(mCꢀS((ꢀ?@"ꢁꢀB7CB7DEF<7<<77777<
; ;
!8(ꢀ'4O04+ꢀ>8)*(ꢀ,<4+).4,-ꢀ,PꢀP02P02)'ꢀ.,ꢀSA5ꢀ0*4-3ꢀU @ ꢀ4*ꢀ
%
4
&
'()*(ꢀ+,ꢀ-,.ꢀ)+/0*.ꢀ1)234-*

&
'()*( Gꢀ +r ,e ꢀe- n, C. ꢀ h) +e /m0 *i s. tꢀ 1r y)234-*
Page 2 of 14
View Article Online
DOI: 10.1039/C9GC04221K
A:;9 <=
>.2'(!#ꢀ?!0+
X BB
5
)*(*ꢀꢀ5',*(ꢀ.,ꢀE7ꢀ^ꢀ = RCꢀU,Z(6(2=ꢀ.8(ꢀ5022(-.ꢀ8438ꢀ>245(ꢀ,Pꢀ +(1,-*.2).(+Cꢀ (-(Z)L'(ꢀTA5ꢀ5)-ꢀL(ꢀ>2,+05(+ꢀL:ꢀP,2ꢀ4-*.)-5(ꢀ
ꢀ1)e(*ꢀ.8(ꢀ>2,+05.4,-ꢀ,Pꢀ#Xꢀ+45)2L,<:'45ꢀ)54+*ꢀ'4e(ꢀ1)'(45ꢀ .8(ꢀ*,M5)''(+ꢀ@<TAꢀ>2,5(**ꢀB[pBbꢀ,2ꢀ)*ꢀ)ꢀL:M>2,+05.ꢀ4-ꢀ.8(ꢀ
Ba
U
@
; ;
)
; ;
-+ꢀ*0554-45ꢀ0-)PP,2+)L'(ꢀ.82,038ꢀ.84*ꢀU @ M+246(-ꢀ,<4+).4,-=ꢀ >2,+05.4,-ꢀ,Pꢀ'(60'4-45ꢀ)54+ꢀP2,1ꢀ'43-,5(''0',*(ꢀ Cꢀ (-(Z)L'(ꢀ
Z8(-ꢀ 5,1>)2(+ꢀ Z4.8ꢀ .8(ꢀ >(.2,58(145)'ꢀ )-+ꢀ P(21(-.).4,-ꢀ GA5ꢀ5)-ꢀL(ꢀ>2,+05(+ꢀL:ꢀ,<4+).4,-ꢀ,Pꢀ+4PP(2(-.ꢀ'43-,5(''0',*(ꢀ
,0.(*ꢀB;C
-ꢀ.84*ꢀZ,2eꢀZ(ꢀ4-6(*.43).(ꢀ)ꢀ+4PP(2(-.ꢀ2,0.(ꢀ.,ꢀ>2,+05(ꢀSA5ꢀ 8:+2,<:1(.8:'P02P02)'ꢀ ;Bp;X=ꢀ )-+ꢀ P02P02)'ꢀ
P2,1ꢀ GA5ꢁꢀ .8(ꢀ )O0(,0*ꢀ >8)*(ꢀ 8:+2,3(-).4,-ꢀ 0*4-3ꢀ #,-*(O0(-.':=ꢀ0*4-3ꢀL4,ML)*(+ꢀTA5ꢀ)-+ꢀGA5ꢀZ4''ꢀ.02-ꢀ.8(ꢀSA5ꢀ
2,+05(+ꢀ4-.,ꢀ)ꢀ2(-(Z)L'(ꢀ58(145)'Cꢀ"-ꢀ.84*ꢀZ,2eꢀZ(ꢀ.)e(ꢀ.8(ꢀ
+(246(+ꢀ >').P,21*=ꢀ 4C(Cꢀ L0.)-,'ꢀ =ꢀ '(60'4-45ꢀ )54+=ꢀ ꢀ
BE
;7
2
;[p;E D7pDD
"
= Cꢀ
>
!
"#$%&ꢀ#&%'ꢀ( !"A&)
P42*.ꢀ*.(>ꢀ.,ꢀ1)e(ꢀ.84*ꢀ>,**4L'(ꢁꢀ.,ꢀ+(1,-*.2).(ꢀ.8).ꢀ.8(ꢀP,2145ꢀ
)54+M+246(-ꢀ8:+2,3(-).4,-ꢀ,PꢀGA5ꢀ4-ꢀ)O0(,0*ꢀ>8)*(ꢀ4*ꢀ(PP454(-.ꢀ
/
0
)
-+ꢀ.(58-45)'':ꢀ)-+ꢀ(-642,-1(-.)'':ꢀ64)L'(Cꢀ
/
/
TA5ꢀ4*ꢀ)ꢀZ(''Me-,Z-ꢀ8:+2,3(-).4-3ꢀ)3(-.ꢀ,Pꢀ)ꢀ6)24(.:ꢀ,Pꢀ,23)-45ꢀ
DX
/
0
P0-5.4,-)'4.4(*ꢀ'4e(ꢀ#`#=ꢀ#`@ꢀ)-+ꢀ#M@ꢀ32,0>*ꢀ CꢀU,Z(6(2=ꢀ.,ꢀ.8(ꢀ
L(*.ꢀ,Pꢀ,02ꢀe-,Z'(+3(=ꢀ.8(ꢀTA5ꢀ1(+4).(+ꢀ8:+2,3(-).4,-ꢀ,Pꢀ
,
'(P4-*ꢀ8)*ꢀL((-ꢀ5,-+05.(+ꢀ4-ꢀ,23)-45ꢀ*,'6(-.*ꢀ)-+ꢀZ4.8ꢀ)-ꢀ
(<5(**ꢀ,PꢀTA5Cꢀ!8(2(ꢀ4*ꢀ)ꢀ')5eꢀ,Pꢀ4-6(*.43).4,-*ꢀ2(3)2+4-3ꢀ.8(ꢀ0*(ꢀ
PꢀZ).(2ꢀ)*ꢀ*,'6(-.ꢀ)-+ꢀ,Pꢀ)ꢀ*.,4584,1(.245ꢀ)1,0-.ꢀ,PꢀTA5Cꢀ
,
!&&%-%&ꢀ#&%'ꢀ(,A&)
*#+.%&ꢀ#&%'ꢀ(*A&)
,
/
0
(
5(-.':ꢀV8(-3ꢀ(.ꢀ)'Cꢀ8)6(ꢀ2(>,2.(+ꢀ.8(ꢀ)O0(,0*ꢀ>8)*(ꢀTA5M
/
/
0
/
/
1
(+4).(+ꢀ>2,+05.4,-ꢀ,Pꢀ*0554-45ꢀ)54+=ꢀL0.ꢀP2,1ꢀ.8(ꢀ.2)-*ꢀ4*,1(2ꢀ
/
0
/
/
0
,Pꢀ GA5=ꢀ P01)245ꢀ )54+=ꢀ )-+ꢀ 0*4-3ꢀ .Z45(ꢀ .8(ꢀ *.,4584,1(.245ꢀ
D[
)
1,0-.ꢀ,PꢀP,2145ꢀ)54+ꢀ CꢀA*ꢀZ(ꢀZ4''ꢀ*8,Zꢀ').(2=ꢀ.84*ꢀ4*,1(2ꢀ4*ꢀ
,2(ꢀ ()*4':ꢀ 2(+05(+ꢀ Z4.8ꢀ TA5ꢀ .8)-ꢀ GA5Cꢀ g(*4+(*=ꢀ )ꢀ
,1,3(-(,0*ꢀ&+QA5@R ꢀ5).)':*.ꢀZ)*ꢀ0.4'4I(+=ꢀZ8458ꢀ4*ꢀ+4PP450'.ꢀ
,ꢀ *(>)2).(ꢀ P2,1ꢀ .8(ꢀ 2()5.4,-ꢀ 14<.02(ꢀ )-+ꢀ 5,-*(O0(-.':ꢀ
1
8
;
/
0
/0
.
/
>2,L'(1).45ꢀ.,ꢀ2(0*(ꢀ)-+=ꢀ1,2(ꢀ41>,2.)-.=ꢀ.8(ꢀ4-5,2>,2).4,-ꢀ,Pꢀ
d)-.>8,*ꢀ QX=[Mg4*Q+4>8(-:'>8,*>84-,RME=EM+41(.8:'<)-.8(-(Rꢀ
/
/
0
)*ꢀ)ꢀ'43)-+ꢀZ)*ꢀ2(O042(+ꢀ.,ꢀ2()58ꢀEXꢀ^ꢀSA5ꢀ:4('+ꢀ)P.(2ꢀ;7ꢀ8ꢀ,Pꢀ
*
#+%&ꢀ#&%'ꢀ(*#+A&)
2
2
()5.4,-CꢀY,ꢀ2(*0'.*ꢀ2(3)2+4-3ꢀ.8(ꢀ*.)L4'4.:ꢀ,Pꢀ.84*ꢀ5).)':*.ꢀZ)*ꢀ
(>,2.(+ꢀ )'.8,038ꢀ ',-3ꢀ .(21ꢀ *.)L4'4.:ꢀ 4*ꢀ 2(O042(+ꢀ P,2ꢀ )-ꢀ
S58(1(ꢀB
4
-+0*.24)'ꢀ)>>'45).4,-CꢀW4.84-ꢀ.84*ꢀ5,-.(<.=ꢀ*,'4+ꢀ5).)':*.*ꢀ)2(ꢀ)ꢀ
058ꢀL(..(2ꢀ,>.4,-ꢀZ8(-ꢀ5,-*4+(24-3ꢀ)ꢀ>2)5.45)'ꢀ)>>'45).4,-ꢀ
;
Cꢀ!84*ꢀ)>>2,)58ꢀ
L(5)0*(ꢀ.8(:ꢀ5)-ꢀ2()+4':ꢀL(ꢀ0*(+ꢀ4-ꢀ)ꢀP4<(+ꢀL(+ꢀ2()5.,2ꢀ0-+(2ꢀ
1
*
.,4584,1(.245ꢀP,2145ꢀ)54+ꢀQTA5Rꢀ)*ꢀ*,025(ꢀ,PꢀU
>2(*(-.*ꢀ P().02(*ꢀ )'43-(+ꢀ Z4.8ꢀ .8(ꢀ >24-54>'(*ꢀ ,Pꢀ 32((-ꢀ
5
,-.4-0,0*ꢀ,>(2).4,-C
5
8(14*.2:CꢀT42*.=ꢀ4-*.()+ꢀ,Pꢀ0*4-3ꢀ,23)-45ꢀ*,'6(-.*=ꢀZ(ꢀ0*(+ꢀ
Aꢀ1058ꢀ*41>'(2=ꢀ1,2(ꢀ)5.46(ꢀ)-+ꢀ2,L0*.ꢀ*,'4+ꢀ5).)':*.ꢀQ5)2L,-ꢀ
Z).(2=ꢀ.8(ꢀ32((-(2ꢀ*,'6(-.CꢀS(5,-+=ꢀ.8(ꢀ0.4'4I).4,-ꢀ,PꢀP,2145ꢀ)54+ꢀ
*0>>,2.(+ꢀ&+ꢀ5).)':*.RꢀZ)*ꢀ4+(-.4P4(+ꢀ4-ꢀ,02ꢀZ,2eCꢀW(ꢀ*8,Zꢀ.8).ꢀ
>
2(6(-.*ꢀ*.,24-3ꢀ)-+ꢀ8)-+'4-3ꢀ,PꢀU
Z8(-ꢀ5,-+05.4-3ꢀ.8(ꢀ2()5.4,-ꢀZ4.8ꢀU
.,4584,1(.245ꢀU ꢀ>2(**02(ꢀ4*ꢀ-((+(+ꢀ6(2*0*ꢀ.8(ꢀ*.,4584,1(.245ꢀ
1,0-.ꢀ,PꢀP,2145ꢀ)54+ꢀ+(1,-*.2).(+ꢀ4-ꢀ.84*ꢀZ,2eCꢀT4-)'':=ꢀ)*ꢀ4.ꢀ
;
ꢀ).ꢀ8438ꢀ>2(**02(Cꢀ!842+=ꢀ
.
84*ꢀ5).)':*.ꢀ5,-+05.*ꢀ.8(ꢀ2()5.4,-ꢀ).ꢀ*414')2ꢀ.(1>(2).02(*ꢀ)-+ꢀ
;
=ꢀ)-ꢀ4-(PP454(-.ꢀ(<5(**ꢀ,Pꢀ
>
>
2(**02(*ꢀ.,ꢀ.8,*(ꢀ0*(+ꢀ4-ꢀ.8(ꢀU
;
M4-+0*.24)'ꢀ>(.2,58(145)'ꢀ
*
;
2,5(**Cꢀ W(ꢀ )'*,ꢀ +(1,-*.2).(ꢀ .8).ꢀ .8(ꢀ >2,5(**ꢀ 5)-ꢀ L(ꢀ
)
5
,-+05.(+ꢀ4-ꢀZ).(2ꢀ)-+ꢀ0*4-3ꢀ)ꢀ*.,4584,1(.245ꢀ)1,0-.ꢀ,PꢀP,2145ꢀ
Z4''ꢀ L(ꢀ )'*,ꢀ +(1,-*.2).(+ꢀ )',-3ꢀ .84*ꢀ )2.45'(=ꢀ .8(ꢀ 5).)':.45ꢀ
)
54+Cꢀ!8(ꢀ5).)':*.ꢀZ(ꢀ2(>,2.ꢀ8(2(ꢀ*8,Z*ꢀ6(2:ꢀ(PP454(-.ꢀ).,1ꢀ
5,-,1:ꢁꢀB77ꢀ^ꢀ,Pꢀ.8(ꢀUꢀ).,1*ꢀ,PꢀP,2145ꢀ)54+ꢀ(-+(+ꢀ4-ꢀ.8(ꢀ
.
2)-*P(2ꢀ8:+2,3(-).4,-ꢀZ4.8ꢀP,2145ꢀ)54+ꢀ)'',Z*ꢀ2(+054-3ꢀ*,1(ꢀ
(
,
Pꢀ .8(ꢀ (-642,-1(-.)'ꢀ 41>)5.ꢀ 5)0*(+ꢀ L:ꢀ .8(ꢀ 5,-6(-.4,-)'ꢀ
:+2,3(-).4,-ꢀ>).8Z):C
*
0554-45ꢀ)54+ꢀ1,'(50'(ꢀ)-+ꢀ5',*(ꢀ.,ꢀB77ꢀ^ꢀ,PꢀGA5ꢀ(-+(+ꢀ0>ꢀ)*ꢀ
8
SA5ꢀQP,21).4,-ꢀ,Pꢀ1)'45ꢀ)-+ꢀP01)245ꢀ)54+ꢀ4*ꢀ-(3'434L'(RCꢀW(ꢀ8)6(ꢀ
A-ꢀ)++4.4,-)'ꢀ6(2:ꢀ4-.(2(*.4-3ꢀP().02(ꢀ,Pꢀ.84*ꢀ>2,5(**ꢀ4*ꢀ.8).ꢀSA5ꢀ
)
'*,ꢀ>2,6(+ꢀ.8(ꢀ',-3M.(21ꢀ*.)L4'4.:ꢀ)-+ꢀ2,L0*.-(**ꢀ,Pꢀ.8(ꢀ
).)':*.ꢀ4-ꢀ)ꢀP4<(+ꢀL(+ꢀ2()5.,2ꢀP((+4-3ꢀ2(').46(':ꢀ5,-5(-.2).(+ꢀ
,'0.4,-*ꢀ,PꢀGA5ꢀP,2ꢀ,6(2ꢀbD7ꢀ8C
<>(241(-.)'
4*ꢀ()*4':ꢀ*(>)2).(+ꢀP2,1ꢀ.8(ꢀ+,Z-*.2()1ꢀ'4O04+ꢀL:ꢀ>2(54>4.).4,-ꢀ
5
+
;
0(ꢀ.,ꢀ4.*ꢀ2(').46(':ꢀ',Zꢀ*,'0L4'4.:ꢀ4-ꢀU @ꢀQ;Ci[ꢀ^ꢀ).ꢀ[ꢀ\#=ꢀXC;iꢀ^ꢀ
*
BD
).ꢀ B7ꢀ \#R Cꢀ !84*ꢀ 1()-*ꢀ .8).ꢀ Z8(-ꢀ P((+4-3ꢀ 2(').46(':ꢀ
%
5
,-5(-.2).(+ꢀGA5=ꢀZ8458ꢀ4*ꢀ1058ꢀ1,2(ꢀ*,'0L'(ꢀ.8)-ꢀS)5ꢀQDBCi;ꢀ
BX
^ꢀ).ꢀ[ꢀ\#R =ꢀ1,*.ꢀ,Pꢀ.8(ꢀSA5ꢀ4*ꢀ>2(54>4.).(+ꢀ+,Z-*.2()1ꢀL:ꢀ
:
41>'(ꢀ5,,'4-3ꢁꢀ.8(ꢀ',Z(2ꢀ.8(ꢀ.(1>(2).02(=ꢀ.8(ꢀ1,2(ꢀSA5ꢀ
+!/+(")ꢀ!(-ꢀ&!"!#$)")
*
G)'(45ꢀ)54+ꢀQEEꢀZ.Cꢀ^R=ꢀP,2145ꢀ)54+ꢀQEaꢀZ.Cꢀ^R=ꢀ.)2.)245ꢀ)54+ꢀQEEꢀ
Z.Cꢀ^R=ꢀ1)'45ꢀ)54+ꢀQEEꢀZ.Cꢀ^R=ꢀP01)245ꢀ)54+ꢀQEEꢀZ.Cꢀ^Rꢀ)-+ꢀ
>2(54>4.).(*Cꢀ!8(ꢀ2(1)4-4-3ꢀ*,'0.4,-ꢀ,Pꢀ+4'0.(+ꢀSA5ꢀ5)-ꢀL(ꢀ
2
(5:5'(+ꢀL)5eꢀ.,ꢀ.8(ꢀ2()5.,2Cꢀ!84*ꢀ4*ꢀ)ꢀ1058ꢀ*.2)438.P,2Z)2+ꢀ)-+ꢀ
'
(60'4-45ꢀ )54+ꢀ QEEꢀ Z.Cꢀ ^Rꢀ Z(2(ꢀ *0>>'4(+ꢀ L:ꢀ S431)ꢀ A'+2458Cꢀ
,11(254)'ꢀ5).)':*.*ꢀL)*(+ꢀ,-ꢀ>)'')+401=ꢀ>').4-01=ꢀ20.8(-401ꢀ
-+ꢀ28,+401ꢀQ[ꢀZ.C^Rꢀ*0>>,2.(+ꢀ,-ꢀ)5.46).(+ꢀ58)25,)'ꢀZ(2(ꢀ
0>>'4(+ꢀL:ꢀS431)ꢀA'+2458Cꢀ#)2L,-ꢀ*0>>,2.(+ꢀ3,'+ꢀ5).)':*.ꢀZ)*ꢀ
2(>)2(+ꢀL:ꢀ)ꢀ+(>,*4.4,-M>2(54>4.).4,-ꢀ>2,.,5,'ꢀ+(*524L(+ꢀ1,2(ꢀ
*
41>'(2ꢀ>2,.,5,'ꢀ.8)-ꢀ.8).ꢀ2(O042(+ꢀP,2ꢀ.8(ꢀ*(>)2).4,-ꢀ)-+ꢀ
#
>
024P45).4,-ꢀSA5ꢀ,L.)4-(+ꢀL:ꢀP(21(-.).4,-C
)
"
-.(2(*.4-3':=ꢀ)'.8,038ꢀL,.8ꢀTA5ꢀ)-+ꢀGA5ꢀ)2(ꢀ5022(-.':ꢀ+(246(+ꢀ
*
P2,1ꢀ P,**4'ꢀ P((+*.,5e*=ꢀ .8(42ꢀ >,.(-.4)'ꢀ >2,+05.4,-ꢀ P2,1ꢀ
>
'43-,5(''0',*45ꢀ P((+*.,5e*ꢀ 8)*ꢀ )'2()+:ꢀ L((-ꢀ .(58-45)'':ꢀ
4-ꢀ +(.)4'ꢀ 4-ꢀ .8(ꢀ S0>>'(1(-.)2:ꢀ ?).)ꢀ Q%S"Rꢀ *(5.4,-Cꢀ !8(ꢀ
@
ꢀnꢀHVꢀX 60C=ꢀ;7B;=ꢀꢁꢁ=ꢀBMD
!84*ꢀ/,02-)'ꢀ4*ꢀoꢀ!8(ꢀ ,:)'ꢀS,54(.:ꢀ,Pꢀ#8(14*.2:ꢀ;7<<
&
'()*(ꢀ+,ꢀ-,.ꢀ)+/0*.ꢀ1)234-*

Page 3 of 14
&'()*( Gꢀ +r ,e ꢀe- n, C. ꢀ h) +e /m0 *i s. tꢀ 1r y)234-*
View Article Online
DOI: 10.1039/C9GC04221K
>.2'(!#ꢀ?!0+
ꢀA:;9 <=
>2(>)2).4,-ꢀ,Pꢀ&+ꢀ*0>>,2.(+ꢀ,-ꢀ+4PP(2(-.ꢀ*0>>,2.*ꢀ4*ꢀ)'*,ꢀ 5).)':*.*ꢀZ(2(ꢀ(<M*4.0ꢀ2(+05(+ꢀ4-ꢀ)ꢀ.0L0')2ꢀ2()5.,2ꢀ0-+(2ꢀ)ꢀB7ꢀ
B
B
+
(*524L(+ꢀ4-ꢀ.8(ꢀ%S"ꢀ*(5.4,-C
6F6^ꢀU
ꢀ)-+ꢀ.8(-ꢀ>)**46).(+ꢀZ4.8ꢀ)ꢀBC[ꢀ6F6^ꢀ@
.(1>(2).02(ꢀ,6(2-438.ꢀL(P,2(ꢀL(4-3ꢀ.2)-*P(22(+ꢀ.,ꢀ.8(ꢀ2()5.,2ꢀ
8(ꢀ&+ꢀ5,-.(-.ꢀ,Pꢀ.8(ꢀP2(*8ꢀ)-+ꢀ0*(+ꢀ5).)':*.*ꢀZ)*ꢀ+(.(214-(+ꢀ 6(**('CꢀA42ꢀZ)*ꢀ2(1,6(+ꢀP2,1ꢀ.8(ꢀ2()5.,2ꢀL:ꢀP'0*84-3ꢀZ4.8ꢀY ꢀP,2ꢀ
L:ꢀ "#&MA%Sꢀ ).ꢀ J)'L2)4.8ꢀ $)L,2).,24(*=ꢀ "-5Cꢀ 0*4-3ꢀ )ꢀ *,+401ꢀ [ꢀ14-ꢀ4-ꢀ.8(ꢀ5)*(ꢀ,Pꢀ3')**ꢀ2()5.,2*ꢀ)-+ꢀP46(ꢀ5:5'(*ꢀ,Pꢀ>2(**024I4-3ꢀ
(2,<4+(ꢀ P0*4,-ꢀ >2,.,5,'ꢀ P,2ꢀ >2(.2().4-3ꢀ .8(ꢀ *)1>'(Cꢀ "-ꢀ ).ꢀi7ꢀL)2ꢀ,PꢀY F+(>2(**024I4-3ꢀP,2ꢀ.8(ꢀ*.)4-'(**ꢀ*.(('ꢀ2()5.,2CꢀT,2ꢀ
011)2:ꢀ*)1>'(*ꢀZ(2(ꢀP0**(+ꢀZ4.8ꢀ*,+401ꢀ>(2,<4+(ꢀ,6(2ꢀ)ꢀ .8(ꢀ')..(2ꢀ5)*(=ꢀ.8(ꢀ2()5.,2ꢀZ)*ꢀ>2(**024I(+ꢀ).ꢀ.8(ꢀ*('(5.(+ꢀY
g0-*(-ꢀ L02-(2ꢀ )-+ꢀ *0L*(O0(-.':ꢀ .8(ꢀ P0*(+ꢀ *)1>'(ꢀ Z)*ꢀ >2(**02(ꢀ>24,2ꢀ.,ꢀ5,-+05.ꢀ.8(ꢀ(<>(241(-.*C
4**,'6(+ꢀ4-ꢀZ).(2Cꢀ!8(ꢀ&+ꢀ'()58(+ꢀ4-.,ꢀ.8(ꢀ2()5.4,-ꢀ14<.02(*ꢀ !8(ꢀ2()5.,2ꢀZ)*ꢀ.8(-ꢀ411(2*(+ꢀ4-ꢀ)ꢀ*4'45,-(ꢀL).8ꢀ*(.ꢀ).ꢀ.8(ꢀ
Z)*ꢀ)-)':I(+ꢀZ4.8,0.ꢀ>2(64,0*ꢀ+43(*.4,-ꢀ0*4-3ꢀ)-ꢀ"#&M@%Sꢀ *('(5.(+ꢀ.(1>(2).02(ꢀQ. ꢀ,Pꢀ.8(ꢀ(<>(241(-.Rꢀ)-+ꢀ*.422(+ꢀ).ꢀB777ꢀ
>(5.2,>8,.,1(.(2ꢀQ&qE777ꢀA-)':.4eꢀ9(-)RCꢀ 2>1ꢀP,2ꢀ)ꢀ346(-ꢀ2()5.4,-ꢀ.41(Cꢀ!,ꢀ*.,>ꢀ.8(ꢀ2()5.4,-=ꢀ.8(ꢀ2()5.,2ꢀ
8(ꢀ)6(2)3(ꢀ*02P)5(ꢀ*4I(ꢀ,Pꢀ&+ꢀ>)2.45'(*ꢀZ)*ꢀ+(.(214-(+ꢀL:ꢀ Z)*ꢀ.)e(-ꢀ,0.ꢀP2,1ꢀ.8(ꢀ*4'45,-(ꢀL).8ꢀ)-+ꢀ'(.ꢀ4.ꢀ5,,'ꢀ+,Z-ꢀ.,ꢀ
;
FA2ꢀP',ZꢀQ[7ꢀ1$c14-M Rꢀ).ꢀ;77ꢀ\#ꢀQ2)1>ꢀB\#c14-M RꢀP,2ꢀ;ꢀ
8
;
FA2ꢀP',Zꢀ).ꢀ2,,1ꢀ
,
!'!&"+'%C!"%.(ꢀ.*ꢀ",+ꢀ&!"!#$)")
!
;
>
;
*
;
ꢀ
+
7
*
!
U !%Gꢀ)-+ꢀ#@ꢀ58(14*,2>.4,-CꢀU !%Gꢀ1452,*5,>:ꢀ>45.02(*ꢀ 2,,1ꢀ.(1>(2).02(Cꢀ!8(ꢀ2()5.,2ꢀZ)*ꢀ+(>2(**024I(+ꢀ)-+ꢀ)ꢀe-,Z-ꢀ
Z(2(ꢀ.)e(-ꢀ0*4-3ꢀ)ꢀ9%@$ꢀ9%GM;B77ꢀTꢀ1,+('ꢀ1452,*5,>(=ꢀZ,2e4-3ꢀ )1,0-.ꢀQ)2,0-+ꢀ7C[ꢀ3Rꢀ,Pꢀ)-ꢀ)O0(,0*ꢀ'(60'4-45ꢀ)54+ꢀQ$A5Rꢀ
Z4.8ꢀ)-ꢀ)55('(2).4,-ꢀ6,'.)3(ꢀ,PꢀD77ꢀe_CꢀS)1>'(*ꢀZ(2(ꢀ>2(>)2(+ꢀ *,'0.4,-ꢀ Q)2,0-+ꢀ 7CB[M7C;7ꢀ 3ꢀ ,Pꢀ $A5ꢀ F3ꢀ ,Pꢀ *,'0.4,-Rꢀ Z)*ꢀ
L:ꢀ0'.2)*,-45)'':ꢀ+4*>(2*4-3ꢀ*,1(ꢀ>,Z+(2ꢀ*)1>'(ꢀ4-ꢀ)L*,'0.(ꢀ 4-5,2>,2).(+ꢀ.,ꢀ.8(ꢀ2()5.4,-ꢀ14<.02(ꢀ)*ꢀ)-ꢀ4-.(2-)'ꢀ*.)-+)2+Cꢀ
(
!
.8)-,'ꢀ)-+ꢀ>0..4-3ꢀ)ꢀ+2,>'(.ꢀ,Pꢀ.8(ꢀ*0*>(-*4,-ꢀ,-ꢀ)ꢀ#0ꢀ324+Cꢀ !84*ꢀ*,'0.4,-ꢀZ)*ꢀP4'.(2(+ꢀ.82,038ꢀ)ꢀ7C;;ꢀr1ꢀ*:24-3(ꢀP4'.(2ꢀ)-+ꢀ
8(ꢀ+4)1(.(2ꢀ,Pꢀ1,2(ꢀ.8)-ꢀ;[7ꢀ&+ꢀ>)2.45'(*ꢀZ)*ꢀ1()*02(+ꢀ.,ꢀ )-)':I(+ꢀ4-ꢀ)-ꢀA34'(-.ꢀB;77ꢀU&$#ꢀ582,1).,32)>8ꢀ(O04>>(+ꢀZ4.8ꢀ
5
)'50').(ꢀ.8(ꢀ)6(2)3(ꢀ*02P)5(ꢀ+4)1(.(2C
)ꢀ2(P2)5.4,-ꢀ4-+(<ꢀ+(.(5.,2=ꢀ)-+ꢀ)ꢀg4,M )+ꢀA14-(<ꢀU&dMabUꢀ
8(ꢀ )1,0-.ꢀ ,Pꢀ #@ꢀ 58(14*,2L(+ꢀ ,6(2ꢀ &+ꢀ >)2.45'(*ꢀ Z)*ꢀ 5,'01-ꢀQD77ꢀ11ꢀ<ꢀbCaꢀ11RCꢀAꢀ7C77[ꢀGꢀU S@ ꢀ1,L4'(ꢀ>8)*(ꢀZ)*ꢀ
(.(214-(+ꢀL:ꢀ.8(ꢀL2()e.82,038ꢀ5026(*ꢀ,L.)4-(+ꢀL:ꢀ*Z4.584-3ꢀ (1>',:(+ꢀ).ꢀD;aꢀsꢀ)-+ꢀ)ꢀ7Caꢀ1$F14-ꢀP',Zꢀ2).(CꢀGA5ꢀ5,-6(2*4,-ꢀ
8(ꢀP((+ꢀP2,1ꢀ,-':ꢀA2ꢀ.,ꢀ)ꢀP',Zꢀ5,-.)4-4-3ꢀA2=ꢀU(ꢀ)-+ꢀ#@CꢀU('401ꢀ )-+ꢀ>2,+05.ꢀ:4('+*ꢀZ(2(ꢀ5)'50').(+ꢀ)55,2+4-3ꢀ.,ꢀ.8(ꢀP,'',Z4-3ꢀ
!
;
X
+
.
4
*ꢀ0*(+ꢀ.,ꢀ.2)5(ꢀ.8(ꢀ+()+ꢀ6,'01(ꢀ,Pꢀ.8(ꢀ2()5.,2ꢀ)-+ꢀ.,ꢀ*(.ꢀ.41(ꢀ P,210')*ꢁ
*/ A!0 * A!
`
ꢀ7ꢀP,2ꢀ.8(ꢀL2()e.82,038ꢀ5026(*CꢀAꢀ5)2(P0'ꢀ+(*524>.4,-ꢀ,Pꢀ.8(ꢀ
<>(241(-.ꢀ4*ꢀ+(*524L(+ꢀ4-ꢀ.8(ꢀS0>>'(1(-.)2:ꢀ?).)ꢀ*(5.4,-=ꢀ4-ꢀ
A!ꢀ!"#$%&'("#ꢀ)*"+ꢀ,-.ꢀ
ꢀ1ꢀ2//
(
*/
A!
*
8,2.=ꢀ.8(ꢀ>2,.,5,'ꢀ4*ꢀ)*ꢀP,'',Z*Cꢀ!8(ꢀ*)1>'(*ꢀQ[7ꢀ13RꢀZ(2(ꢀ
,)+(+ꢀ4-ꢀ)ꢀ]M.0L(ꢀ2()5.,2ꢀZ8458ꢀ(<4.ꢀ4*ꢀ5,--(5.(+ꢀ.,ꢀ)ꢀG)**ꢀ
S>(5.2,1(.(2ꢀ4-ꢀ,2+(2ꢀ.,ꢀ)-)':I(ꢀ4-ꢀ2()'ꢀ.41(ꢀ.8(ꢀ5,1>,*4.4,-ꢀ
Pꢀ.8(ꢀ3)*(*ꢀ(<4.4-3ꢀ.8(ꢀ2()5.,2Cꢀ!Z,ꢀ5:5'(*ꢀZ(2(ꢀ5,-+05.(+=ꢀ4-ꢀ
*
8&"4
'
3
&"45!6ꢀ7(%+4ꢀ)*"+ꢀ,-.ꢀ
ꢀ1ꢀ2//
*/
A!
,
*
9A!
.
8(ꢀP42*.ꢀ5:5'(ꢀ.8(ꢀ#@ꢀL2()e.82,038ꢀ5026(ꢀ4*ꢀ+('):(+ꢀZ4.8ꢀ 9%+%!6($(67ꢀ":ꢀ9A!ꢀ) A!ꢀ*"+ꢀ,ꢀ;<'('-.ꢀ
(*>(5.ꢀ .,ꢀ .`7ꢀ +0(ꢀ .,ꢀ 422(6(2*4L'(ꢀ )-+ꢀ 2(6(2*4L'(ꢀ #@ꢀ
ꢀ1ꢀ2//
*/
A!0 * A!
2
5
8(14*,2>.4,-Cꢀ@-5(ꢀ#@ꢀ*43-)'ꢀ2()58(*ꢀ)ꢀ*.()+:ꢀ6)'0(ꢀQD7ꢀ14-CRꢀ
8(ꢀP((+ꢀ*Z4.58(*ꢀL)5eꢀ.,ꢀ,-':ꢀA2Cꢀ@-5(ꢀ#@ꢀ4*ꢀP0'':ꢀ2(1,6(+ꢀ
P2,1ꢀ.8(ꢀP',ZꢀQ-,ꢀ#@ꢀ*43-)'ꢀ4*ꢀ+(.(5.(+Rꢀ)ꢀ*(5,-+ꢀ5:5'(ꢀZ)*ꢀ
*9A!
9
%+%!6($(67ꢀ":ꢀ9A!ꢀ)=A!ꢀ*"+ꢀ,ꢀ;<'('-.ꢀ
ꢀ1ꢀ2//
.
*/
=A!0 *=A!
,-(Cꢀ!8(ꢀ*(5,-+ꢀ#@ꢀL2()e.82,038ꢀ5026(ꢀ4*ꢀ+('):(+ꢀ,-':ꢀ Z8(2(ꢀ17GA5ꢀ)-+ꢀ17TA5ꢀ2(P(2*ꢀ.,ꢀ.8(ꢀ1,'(ꢀO0)-.4.4(*ꢀ4-4.4)'':ꢀ
+
L(5)0*(ꢀ,Pꢀ.8(ꢀ2(6(2*4L'(ꢀ#@ꢀ58(14*,2>.4,-ꢀQ*((ꢀ)-ꢀ(<)1>'(ꢀ4-ꢀ ',)+(+ꢀ4-.,ꢀ.8(ꢀ2()5.,2=ꢀ)-+ꢀ1GA5=ꢀ1TA5=ꢀ1SA5ꢀ)-+ꢀ1>2,+ꢀ2(P(2ꢀ.,ꢀ
T43CꢀS?MBRCꢀ!8(ꢀ+4PP(2(-5(ꢀL(.Z((-ꢀ.8(*(ꢀ.Z,ꢀL2()e.82,038ꢀ .8(ꢀ-01L(2ꢀ,Pꢀ1,'(*ꢀ,Pꢀ.8(ꢀGA5=ꢀTA5=ꢀSA5ꢀ)-+=ꢀ4-ꢀ3(-(2)'=ꢀ,Pꢀ
5
026(*ꢀ4*ꢀ.8(ꢀ422(6(2*4L'(ꢀ#@ꢀ58(14*,2>.4,-Cꢀ!8(ꢀ-01L(2ꢀ,Pꢀ )-:ꢀ>2,+05.ꢀ,Pꢀ.8(ꢀ2()5.4,-=ꢀ2(*>(5.46(':=ꢀ4-ꢀ.8(ꢀ14<.02(ꢀ)P.(2ꢀ
.,1*ꢀ,Pꢀ&+ꢀ).ꢀ.8(ꢀ*02P)5(ꢀ,Pꢀ.8(ꢀ&+ꢀ>)2.45'(*ꢀQ&+*02RꢀZ)*ꢀ 2()5.4,-Cꢀ !8(ꢀ U&$#ꢀ 582,1).,32)>845ꢀ P)5.,2ꢀ ,Pꢀ .8(ꢀ ,23)-45ꢀ
)'50').(+ꢀ)**014-3ꢀ)ꢀ#@F&+*02ꢀ`ꢀBCꢀ!8(ꢀ+4*>(2*4,-ꢀ,Pꢀ&+ꢀZ)*ꢀ >2,+05.*ꢀZ)*ꢀ5)'50').(+ꢀL:ꢀ)-)':I4-3ꢀ*,'0.4,-*ꢀZ4.8ꢀe-,Z-ꢀ
*02F&+.,.)'ꢀ )-+ꢀ .8(ꢀ )6(2)3(ꢀ >)2.45'(ꢀ *4I(ꢀ Z)*ꢀ (*.41).(+ꢀ 5,-5(-.2).4,-*ꢀ,Pꢀ.8(ꢀ+4PP(2(-.ꢀ,23)-45ꢀ>2,+05.*C
P,'',Z4-3ꢀ.8(ꢀ(O0).4,-ꢀ+Q-1Rꢀ`ꢀBCB;F+4*>(2*4,-ꢀDiC
)
5
&
+
4
&-+,-'&'*ꢀ6&30ꢀ:,Y03ꢀ.03ꢀ0Y(0%,60-+*
!8(ꢀ5).)':*.ꢀQ7C[ꢀ3RꢀZ)*ꢀ',)+(+ꢀ4-ꢀ)ꢀtuꢀ*.)4-'(**ꢀ*.(('ꢀ.0L4-3ꢀ)-+ꢀ
,'+ꢀP421':ꢀL(.Z((-ꢀ*4'45)ꢀL(+*ꢀ)-+ꢀO0)2.IꢀZ,,'Cꢀ!8(ꢀ2()5.,2ꢀ
!
"!#$"%&ꢀ!&"%6%"$ꢀ+D4+'%0+(")
8
O +<5ꢀ6&30ꢀ0Y(0%,60-+*
<>(241(-.*ꢀZ(2(ꢀ)'Z):*ꢀ5,-+05.(+ꢀ0-+(2ꢀY
.0L4-3ꢀZ)*ꢀ/)5e(.(+ꢀL:ꢀ)-ꢀ)'014-01ꢀL',5eꢀ.8).ꢀZ)*ꢀ8().(+ꢀL:ꢀ
%
;
ꢀ).1,*>8(2(Cꢀ )-ꢀ('(5.245ꢀP02-)5(Cꢀ!8(ꢀ5).)':*.ꢀQ>)2.45'(ꢀ*4I(ꢀZ)*ꢀ*1)''(2ꢀ.8)-ꢀ
S.)4-'(**ꢀ*.(('ꢀ2()5.,2*ꢀ'4-(+ꢀZ4.8ꢀ)ꢀ!(P',-ꢀ6(**('ꢀZ(2(ꢀ0*(+ꢀ ;77ꢀ!1RꢀZ)*ꢀ',)+(+ꢀ).ꢀ.8(ꢀL,..,1ꢀ>)2.ꢀ,Pꢀ.8(ꢀ2()5.,2ꢀ*,ꢀ.8(ꢀ
Z8(-ꢀ 4-4.4)'ꢀ Y
ꢀ >2(**02(ꢀ Z)*ꢀ )L,6(ꢀ ).1,*>8(245ꢀ >2(**02(ꢀ '4O04+ꢀ 5,-.)5.*ꢀ O045e':ꢀ .8(ꢀ 5).)':*.ꢀ L(+ꢀ )-+ꢀ >2(6(-.*ꢀ .8(ꢀ
Z8(2()*ꢀA5(ꢀ3')**ꢀ2()5.,2*ꢀQB[ꢀ1$RꢀZ(2(ꢀ0*(+ꢀZ8(-ꢀ4-4.4)'ꢀY
ꢀ P,21).4,-ꢀ,Pꢀ0-+(*42)L'(ꢀL:M>2,+05.*ꢀQP01)245ꢀ)-+ꢀ1)'45ꢀ)54+RCꢀ
2(**02(ꢀZ)*ꢀ).1,*>8(245ꢀ>2(**02(CꢀW8(-ꢀ8().(+ꢀ.,ꢀ2()5.4,-ꢀ !,ꢀ1()*02(ꢀ.8(ꢀ.(1>(2).02(ꢀ,Pꢀ.8(ꢀ5).)':*.=ꢀ)ꢀ.8(21,5,0>'(ꢀ
(1>(2).02(ꢀ .8(ꢀ >2(**02(ꢀ 24*(*ꢀ L(5)0*(ꢀ P,2145ꢀ )54+ꢀ Z)*ꢀ4-*(2.(+ꢀL(.Z((-ꢀ.8(ꢀ)'014-01ꢀ/)5e(.ꢀ)-+ꢀ.8(ꢀ2()5.,2=ꢀ
(5,1>,*(*ꢀ.,ꢀ#@ ꢀ)-+ꢀU
Cꢀ"-ꢀ>2)5.45(ꢀ.8(ꢀ(<>(241(-.*ꢀZ(2(ꢀ 5(-.(2(+ꢀ).ꢀ.8(ꢀ>,*4.4,-ꢀZ8(2(ꢀ.8(ꢀ5).)':*.ꢀL(+ꢀZ)*Cꢀ!8(ꢀ
;
;
>
.
+
;
;
5
5
,-+05.(+ꢀ)*ꢀP,'',Z*Cꢀ!8(ꢀ2(O042(+ꢀ)1,0-.*ꢀ,Pꢀ>)**46).(+ꢀ >2(**02(ꢀZ)*ꢀ1)4-.)4-(+ꢀL:ꢀ)ꢀL)5e>2(**02(ꢀ2(30').,2ꢀ*(.ꢀ).ꢀB7ꢀ
).)':*.=ꢀ1)'(45ꢀ)54+=ꢀZ).(2ꢀ)-+ꢀP,2145ꢀ)54+ꢀZ(2(ꢀ',)+(+ꢀ4-.,ꢀ.8(ꢀ L)2Cꢀ&2(**02(ꢀ+2,>ꢀ,Pꢀ5).)':*.ꢀL(+ꢀZ)*ꢀ-(3'434L'(ꢀ)*ꢀ+(.(214-(+ꢀ
2
()5.,2ꢀ)-+ꢀ.,.)'4-3ꢀ[ꢀ3ꢀ,Pꢀ*,'0.4,-Cꢀ]-'(**ꢀ5'()2':ꢀ*.).(+=ꢀ.8(ꢀ L:ꢀ>2(**02(ꢀ3)03(+ꢀ',5).(+ꢀ0>ꢀ)-+ꢀ+,Z-*.2()1ꢀ.8(ꢀ5).)':*.ꢀ
!
84*ꢀ/,02-)'ꢀ4*ꢀoꢀ!8(ꢀ ,:)'ꢀS,54(.:ꢀ,Pꢀ#8(14*.2:ꢀ;7<<
HVꢀX 60C=ꢀ;7BD=ꢀꢁꢁ=ꢀBMDꢀnꢀB
&
'()*(ꢀ+,ꢀ-,.ꢀ)+/0*.ꢀ1)234-*

&
'()*( Gꢀ +r ,e ꢀe- n, C. ꢀ h) +e /m0 *i s. tꢀ 1r y)234-*
Page 4 of 14
View Article Online
DOI: 10.1039/C9GC04221K
A:;9 <=
>.2'(!#ꢀ?!0+
; ;
L(+CꢀA*ꢀ#@ ꢀ)-+ꢀU ꢀ5)-ꢀL(ꢀ2('()*(+ꢀL(5)0*(ꢀ,Pꢀ.8(ꢀ5).)':.45ꢀ Z(2(ꢀ 41>,2.)-.ꢀ P().02(*ꢀ .,ꢀ O0)'4.).46(':ꢀ +4*50**ꢀ .8(ꢀ
+
(5,1>,*4.4,-ꢀ,PꢀP,2145ꢀ)54+=ꢀ-,ꢀ)++4.4,-)'ꢀ3)*ꢀZ)*ꢀ0*(+ꢀ.,ꢀ >(2P,21)-5(ꢀ,Pꢀ.8(ꢀ5).)':*.*CꢀA-,.8(2ꢀ2('(6)-.ꢀ>2,>(2.:ꢀ4*ꢀ.8(ꢀ
e((>ꢀ.8(ꢀ>2(**02(=ꢀ)'.8,038ꢀ+024-3ꢀ.8(ꢀ*.)2.4-3M0>=ꢀ2()5.,2ꢀZ)*ꢀ SA5ꢀ*('(5.464.:=ꢀL,.8ꢀ4-ꢀGA5ꢀ)-+ꢀTA5ꢀL)*4*Cꢀ!8(ꢀ')..(2ꢀ2(P(2*ꢀ.,ꢀ
2(**024I(+ꢀL:ꢀ0*4-3ꢀ)ꢀP',Zꢀ,PꢀY ꢀ.8).ꢀ)'*,ꢀP'0*8(*ꢀ.8(ꢀ2()5.,2ꢀ .8(ꢀUꢀ).,1*ꢀ,PꢀP,2145ꢀ)54+ꢀ.8).ꢀ(-+ꢀ0>ꢀ4-ꢀ.8(ꢀSA5ꢀ1,'(50'(ꢀ
4-(*Cꢀ@-5(ꢀ).ꢀB7ꢀL)2ꢀ)-+ꢀ).ꢀ.8(ꢀ2()5.4,-ꢀ.(1>(2).02(=ꢀ.8(ꢀY ꢀ 2(').46(ꢀ.,ꢀ.8(ꢀ.,.)'ꢀTA5ꢀ.8).ꢀ4*ꢀ5,-6(2.(+Cꢀ
P',ZꢀZ)*ꢀ*.,>>(+ꢀ)-+ꢀ)-ꢀ)O0(,0*ꢀ*,'0.4,-ꢀ,PꢀP,2145ꢀ)54+ꢀ)-+ꢀ ".ꢀ4*ꢀ5'()2ꢀ.8).ꢀ&+F#ꢀ4*ꢀ.8(ꢀ1,*.ꢀ)5.46(ꢀ)-+ꢀ*('(5.46(ꢀ)1,-3ꢀ,Pꢀ
>
;
'
;
1
)'(45ꢀ)54+ꢀZ)*ꢀ>01>(+ꢀL:ꢀ)ꢀJ4'*,-ꢀ>01>ꢀ).ꢀ)ꢀ346(-ꢀP',Zꢀ2).(ꢀ .8(ꢀ+4PP(2(-.ꢀ5).)':*.ꢀ.(*.(+ꢁꢀ4.ꢀ*8,Z(+ꢀ.8(ꢀ8438(*.ꢀ)5.464.:ꢀL,.8ꢀ
Q.
7
ꢀ,Pꢀ.8(ꢀ(<>(241(-.RCꢀS)1>'(*ꢀZ(2(ꢀZ4.8+2)Z-ꢀP2,1ꢀ)ꢀ8438M 4-ꢀGA5ꢀ)-+ꢀTA5ꢀ5,-6(2*4,-ꢀQEEꢀ^ꢀ)-+ꢀ;Xꢀ^=ꢀ2(*>(5.46(':Rꢀ)-+ꢀ
>
2(**02(ꢀ2(*(26,42ꢀ',5).(+ꢀ0>*.2()1ꢀ.8(ꢀL)5e>2(**02(ꢀ2(30').,2ꢀ .8(ꢀ8438(*.ꢀ:4('+ꢀ,PꢀSA5ꢀQEiꢀ^RCꢀ".ꢀ4*ꢀ)'*,ꢀZ,2.8ꢀ*.2(**4-3ꢀ.8).ꢀSA5ꢀ
8).ꢀ)'',Z*ꢀ.8(ꢀ3)*F'4O04+ꢀ*(>)2).4,-ꢀ)-+ꢀ*.,2(ꢀ.8(ꢀ'4O04+*Cꢀ!8(ꢀ
4O04+ꢀ*)1>'(*ꢀZ(2(ꢀ)55010').(+ꢀP,2ꢀ)ꢀ346(-ꢀ>(24,+ꢀ,Pꢀ.41(ꢀ)-+ꢀ !)L'(ꢀBCꢀ#).)':.45ꢀ>2,>(2.4(*ꢀ,Pꢀ+4PP(2(-.ꢀ5)2L,-ꢀ*0>>,2.(+ꢀ
8(-ꢀ 5,''(5.(+ꢀ L:ꢀ +2)4-4-3ꢀ .8(ꢀ 2(*(26,42Cꢀ S)1>'4-3ꢀ )2(ꢀ -,L'(ꢀ1(.)'ꢀ5).)':*.*Cꢀ ()5.4,-ꢀ5,-+4.4,-*ꢁꢀ[ꢀ3ꢀ,Pꢀ2()5.4,-ꢀ
,-+05.(+ꢀL:ꢀP0'':ꢀ(1>.:4-3ꢀ.8(ꢀ'4O04+ꢀ2(*(26,42ꢀZ4.8ꢀ.8(ꢀ8('>ꢀ 14<.02(=ꢀ[ꢀZ.C^ꢀGA5=ꢀBꢀZ.Cꢀ^ꢀ,Pꢀ5).)':*.=ꢀ1,'ꢀTA5FGA5ꢀ`ꢀX=ꢀ
.
'
.
5
,
Pꢀ.8(ꢀ,Z-ꢀ2()5.,2ꢀ>2(**02(Cꢀ!84*ꢀ2(*0'.*ꢀ4-ꢀ)ꢀ>2(**02(ꢀ+2,>ꢀ4-ꢀ BB7ꢀ\#=ꢀ4-4.4)'ꢀY
8(ꢀ2()5.,2ꢀ,PꢀP(Zꢀ.(-.8*ꢀ,PꢀL)2ꢀ.8).ꢀ)2(ꢀ2)>4+':ꢀ5,1>(-*).(+ꢀ
L:ꢀ>2(**024I4-3ꢀ.8(ꢀ0>*.2()1ꢀ'4-(*ꢀZ4.8ꢀY ꢀL:ꢀ1()-*ꢀ,Pꢀ)ꢀ'()eꢀ
)'6(Cꢀ!8(ꢀZ8,'(ꢀ*)1>'4-3ꢀ)-+ꢀ>2(**024I4-3ꢀ,>(2).4,-ꢀ2(O042(*ꢀ
;
ꢀ>2(**02(ꢀ`ꢀBꢀL)2=ꢀ)-+ꢀ.41(ꢀ,Pꢀ2()5.4,-ꢀXꢀ8C
.
G+#8GA&
ꢀ
G+#8GA&
ꢀ
;
JKLꢀ
JKLꢀ
H
IA&ꢀ HMA&ꢀ NGA&ꢀ NI!#A&ꢀ NM20A&ꢀ
6
!
"!#$)"
J7!)+-ꢀ J7!)+-ꢀ
(ꢀ .(ꢀMA&L
JKL JKL JKL JKL
JKL
,Pꢀ '(**ꢀ .8)-ꢀ )ꢀ 14-0.(=ꢀ Z8458ꢀ 4*ꢀ )ꢀ .2)-*4(-.ꢀ -(3'434L'(ꢀ 4-ꢀ
.
5
,1>)24*,-ꢀZ4.8ꢀ.8(ꢀ>(24,+ꢀL(.Z((-ꢀ*)1>'4-3ꢀQ.(-*ꢀ,Pꢀ8,02*RCꢀ
IA&L
D
!
8(ꢀ6,'01(ꢀ+,Z-*.2()1ꢀ.8(ꢀ2()5.,2ꢀ4*ꢀ)2,0-+ꢀB7ꢀ51 =ꢀ*,ꢀP',Zꢀ
P'0*8(*ꢀ.8(ꢀ+,Z-*.2()1ꢀ'4-(*ꢀ4-ꢀ)ꢀ5,0>'(ꢀ,Pꢀ8,02*Cꢀ!Z,ꢀ8,02*ꢀ4-ꢀ
+6)-5(ꢀ,Pꢀ*)1>'4-3=ꢀ.8(ꢀ2(*(26,42ꢀZ)*ꢀ(1>.4(+ꢀ.,ꢀ5,''(5.ꢀ)ꢀ
O-P
2P
EE ;X Ei
E; i ;X
Ea B[ ;X
B
;
B
B
X
D
Eb
;i
;[
;i
BB
B77
B77
X7
)
:
Ba
;X
Ba
Ba
2
(>2(*(-.).46(ꢀ*)1>'(CꢀA5.0)'ꢀ'4O04+ꢀP',Zꢀ2).(ꢀ5,4-54+(+ꢀZ4.8ꢀ
8(ꢀ*(.ꢀP',Zꢀ2).(ꢀZ4.84-ꢀvꢀ;^CꢀAꢀe-,Z-ꢀ)1,0-.ꢀ,Pꢀ.8(ꢀ'4O04+ꢀ
.
A2P
O"P
*)1>'(ꢀZ)*ꢀ)'4O0,.(+ꢀ)-+ꢀ)-)':I(+ꢀL:ꢀU&$#ꢀP,'',Z4-3ꢀ.8(ꢀ*)1(ꢀ
>
2,5(+02(ꢀ+(*524L(+ꢀP,2ꢀL).58ꢀ,>(2).4,-CꢀGA5ꢀ5,-6(2*4,-ꢀ)-+ꢀ
2,+05.ꢀ :4('+*ꢀ Z(2(ꢀ 5)'50').(+ꢀ )55,2+4-3ꢀ .,ꢀ .8(ꢀ P,'',Z4-3ꢀ
iB
X Bi
B77
ab
>
:
,P
ib
;
b
P,210')*ꢁ
dꢁꢀ5,-6(2*4,-=ꢀwꢁꢀ:4('+=ꢀS('Cꢁꢀ*('(5.464.:ꢀ
!/
A!0 ! A!
A!ꢀ!"#$%&'("#ꢀ)*"+,-.ꢀ
ꢀ1ꢀ2//
*('(5.464.:ꢀ4-ꢀGA5ꢀ)-+ꢀTA5ꢀ1,'ꢀL)*4*ꢀ)2(ꢀ)'*,ꢀ.8(ꢀ8438(*.ꢀQEiꢀ^ꢀ
-+ꢀB77ꢀ^=ꢀ2(*>(5.46(':RCꢀ@.8(2ꢀ+4)54+*ꢀ'4e(ꢀ1)'45ꢀ)54+ꢀQG)'A5Rꢀ
!/
A!
)
!
8&"4
)-+ꢀP01)245ꢀ)54+ꢀQT01A5RꢀZ(2(ꢀ)'*,ꢀP,21(+ꢀ2(*>(5.46(':ꢀL:ꢀ
8:+2).4,-ꢀ ,Pꢀ .8(ꢀ +,0L'(ꢀ L,-+ꢀ )-+ꢀ 4*,1(24I).4,-ꢀ ,Pꢀ GA5=ꢀ
3
&"45!6ꢀ7(%+4ꢀ)*"+,-.ꢀ
ꢀ1ꢀ2//
!/
A!
2
(*>(5.46(':=ꢀL0.ꢀ4-ꢀ14-,2ꢀ)1,0-.*Cꢀ
Z8(2(ꢀ<A>ꢁ<ꢀ2(P(2*ꢀ.,ꢀ.8(ꢀ1,'(c3 ꢀ,Pꢀ)'4O0,.ꢀP(+ꢀ4-.,ꢀ.8(ꢀ2()5.,2=ꢀ !8(ꢀ2(*.ꢀ,Pꢀ.8(ꢀ1(.)'*ꢀ>2(*(-.ꢀ)ꢀ1058ꢀ',Z(2ꢀ:4('+ꢀ,PꢀSA=ꢀ64*4L':ꢀ
-+ꢀ<>ꢁ5ꢀ)-+ꢀ<(%&3ꢀ2(P(2ꢀ.,ꢀ.8(ꢀ-01L(2ꢀ,Pꢀ1,'(c3 ꢀ,Pꢀ)'4O0,.ꢀ,Pꢀ ',Zꢀ4-ꢀ.8(ꢀ5)*(ꢀ,Pꢀ&.ꢀ)-+ꢀ 8Cꢀ!8(ꢀ1)4-ꢀ2()*,-ꢀ*((1*ꢀ.,ꢀL(ꢀ.8(ꢀ
MB
MB
)
GA5ꢀ )-+ꢀ >2,+05.*=ꢀ 2(*>(5.46(':=ꢀ 4-ꢀ .8(ꢀ 2()5.4,-ꢀ 14<.02(ꢀ Z,2*(ꢀ5)>)54.:ꢀ,Pꢀ.8(*(ꢀ1(.)'*ꢀ.,ꢀ.2)-*P(2ꢀ.8(ꢀ8:+2,3(-ꢀP2,1ꢀ
B7
*
)1>'(+ꢀ).ꢀ)ꢀ346(-ꢀ.41(ꢀ Cꢀ!8(ꢀ5)2L,-ꢀL)')-5(ꢀZ)*ꢀ5)'50').(+ꢀ TA5ꢀ.,ꢀGA5ꢁꢀ.8(ꢀTA5ꢀ5,-6(2*4,-ꢀP,2ꢀ 0=ꢀA0=ꢀ&.ꢀ)-+ꢀ 8ꢀ4*ꢀ64*4L':ꢀ
,-ꢀGA5ꢀ1,'ꢀL)*4*ꢀ)-+ꢀP,2ꢀ.8(*(ꢀ(<>(241(-.*ꢀZ)*ꢀ)'Z):*ꢀB77ꢀ^ꢀ *1)''(2ꢀ.8)-ꢀ.8).ꢀ,Pꢀ&+Cꢀ"-ꢀ.8(ꢀ5)*(ꢀ,PꢀA0ꢀ.8(ꢀ5,-6(2*4,-ꢀ,Pꢀ
Qv[^RC
P,2145ꢀ)54+ꢀ4*ꢀO04.(ꢀ8438ꢀL0.ꢀ4.*ꢀ(PP(5.46(ꢀ5)>)54.:ꢀ4*ꢀ6(2:ꢀ',Zꢀ
Q,-':ꢀ )2,0-+ꢀ X7ꢀ ^ꢀ ,Pꢀ 5,-6(2.(+ꢀ TA5ꢀ 4*ꢀ 0*(+ꢀ 4-ꢀ .8(ꢀ
8:+2,3(-).4,-RCꢀG,2(,6(2=ꢀ4-ꢀ)''ꢀ.8(*(ꢀ1(.)'*ꢀ.8(2(ꢀ4*ꢀ)ꢀ')5eꢀ,Pꢀ
:
+)2#")ꢀ!(-ꢀF%)&2))%.(
5
)2L,-ꢀL)')-5(ꢀZ4.8ꢀ2(*>(5.ꢀ.,ꢀGA5Cꢀ!80*=ꢀ4-ꢀ.8(ꢀ5)*(ꢀ,Pꢀ 0ꢀ
G"2-$ꢀ.*ꢀ",+ꢀ&!"!#$"%&ꢀ4'.4+'"%+)ꢀ.*ꢀ-%**+'+("ꢀ&!"!#$)")ꢀ!(-ꢀ 5).)':*.ꢀ)2,0-+ꢀXXꢀ^ꢀ,Pꢀ.8(ꢀ5,-6(2.(+ꢀGA5ꢀZ)*ꢀ-,.ꢀ4+(-.4P4(+ꢀ
4"%0%C!"%.(ꢀ.*ꢀ",+ꢀ'+!&"%.(ꢀ4!'!0+"+')
L:ꢀU&$#CꢀAꢀZ84.(ꢀ>2(54>4.).(=ꢀ.8).ꢀ.02-(+ꢀ,0.ꢀ.,ꢀL(ꢀT01A5ꢀZ8(-ꢀ
4**,'6(+ꢀZ4.8ꢀY)@Uꢀ)-+ꢀ)-)':I(+=ꢀ(<>')4-*ꢀ.84*ꢀ')5eꢀ,Pꢀ5)2L,-ꢀ
L)')-5(ꢀQ*,'0L4'4.:ꢀ,PꢀT01A5ꢀ4-ꢀZ).(2ꢀ4*ꢀ)2,0-+ꢀiMaꢀ13c3MBꢀ,Pꢀ
)L'(ꢀBꢀ*011)24I(*ꢀ.8(ꢀ5).)':.45ꢀ>2,>(2.4(*ꢀ,Pꢀ*(6(2)'ꢀ5)2L,-M *,'0.4,-ꢀB7RCꢀ!8(2(P,2(=ꢀT01A5ꢀ:4('+*ꢀ10*.ꢀL(ꢀ8438(2ꢀ.8)-ꢀ.8).ꢀ
0>>,2.(+ꢀ5).)':*.*ꢀL)*(+ꢀ,-ꢀ+4PP(2(-.ꢀ-,L'(ꢀ1(.)'*ꢀQ&+=ꢀ 0=ꢀA0=ꢀ .)L0').(+Cꢀ"-ꢀ>2)5.45(ꢀ4PꢀGA5ꢀ4*ꢀ-,.ꢀ2)>4+':ꢀ8:+2,3(-).(+=ꢀ
.=ꢀ)-+ꢀ 8RCꢀ!8(*(ꢀ1(.)'*ꢀZ(2(ꢀ*('(5.(+ꢀL(5)0*(ꢀ.8(:ꢀ)2(ꢀ)5.46(ꢀ 4*,1(24I(*ꢀ0-+(2ꢀ.8(ꢀ2()5.4,-ꢀ5,-+4.4,-*ꢀ.,ꢀ*5)25(':ꢀ*,'0L'(ꢀ
-+ꢀ*('(5.46(ꢀ4-ꢀ.8(ꢀ+(5,1>,*4.4,-ꢀ,PꢀP,2145ꢀ)54+ꢀ4-.,ꢀ#@ ꢀ)-+ꢀ T01A5Cꢀ !84*ꢀ 4*ꢀ )ꢀ >2,L'(1ꢀ Z8(-ꢀ 5,-*4+(24-3ꢀ )ꢀ >2)5.45)'ꢀ
Cꢀ!8(ꢀ1(.)'ꢀ',)+4-3ꢀZ)*ꢀ4-ꢀ)''ꢀ5)*(*ꢀ)2,0-+ꢀ[ꢀZ.C^Cꢀ!84*ꢀP42*.ꢀ )>>'45).4,-ꢀ0-+(2ꢀ5,-.4-0,0*ꢀ,>(2).4,-ꢀ1,+(ꢀL(5)0*(ꢀT01A5ꢀ
.
+
ꢁ
<+,E0ꢀ60+ /*ꢀ,-ꢀ< %.&-ꢀ*'((&%+03ꢀ< + /2*+*
!
*
&
)
;
U
;
*
.0+:ꢀZ)*ꢀ5,-+05.(+ꢀZ4.8ꢀ)ꢀ1,')2ꢀ2).4,ꢀ,PꢀTA5FGA5ꢀ`ꢀXCꢀ!8(ꢀ >2(54>4.).4,-ꢀ1):ꢀ2(*0'.ꢀ4-ꢀ.8(ꢀ>'0334-3ꢀ,Pꢀ.8(ꢀ2()5.,2Cꢀ"-ꢀ
)1>'(*ꢀZ(2(ꢀ',)+(+ꢀ4-.,ꢀ)-ꢀA5(ꢀ3')**ꢀ2()5.,2ꢀ)*ꢀ2(5(46(+ꢀ *011)2:=ꢀ.8(ꢀP,'',Z4-3ꢀ,2+(2ꢀ5)-ꢀL(ꢀ(*.)L'4*8(+ꢀL(.Z((-ꢀ.8(ꢀ
*
Z4.8,0.ꢀ)-:ꢀ>2(64,0*ꢀ2(+05.4,-ꢀ.2().1(-.Cꢀ!8(ꢀ5,-6(2*4,-ꢀ,Pꢀ 1(.)'*ꢀ4-ꢀ.(21*ꢀ,PꢀSA5ꢀ:4('+
L,.8ꢀGA5ꢀQdGA5Rꢀ)-+ꢀP,2145ꢀ)54+ꢀQdTA5Rꢀ)-+ꢀ.8(ꢀ:4('+ꢀ,PꢀSA5ꢀQwSA5Rꢀ ꢀ&+ꢀxxꢀ 0ꢀ"ꢀA0ꢀxꢀ&.ꢀxꢀ 8
EꢀnꢀHVꢀX 60C=ꢀ;7B;=ꢀꢁꢁ=ꢀBMD
!84*ꢀ/,02-)'ꢀ4*ꢀoꢀ!8(ꢀ ,:)'ꢀS,54(.:ꢀ,Pꢀ#8(14*.2:ꢀ;7<<
&
'()*(ꢀ+,ꢀ-,.ꢀ)+/0*.ꢀ1)234-*

Page 5 of 14
&'()*( Gꢀ +r ,e ꢀe- n, C. ꢀ h) +e /m0 *i s. tꢀ 1r y)234-*
View Article Online
DOI: 10.1039/C9GC04221K
>.2'(!#ꢀ?!0+
ꢀA:;9 <=
#
,-*(O0(-.':=ꢀ&+F#ꢀ5).)':*.ꢀZ)*ꢀ*('(5.(+ꢀP,2ꢀP02.8(2ꢀ*.0+4(*C
G)'A5Cꢀ#,-*(O0(-.':=ꢀ.,ꢀ0*(ꢀTA5FGA5ꢀ5',*(ꢀ.,ꢀBꢀ.8(ꢀ2()5.4,-ꢀ
,-+4.4,-*ꢀ10*.ꢀL(ꢀ58)-3(+ꢀ.,ꢀ4-52()*(ꢀ.8(ꢀ8:+2,3(-).4,-ꢀ2).(ꢀ
+'32ꢀ &:ꢀ +50ꢀ 0::0<+ꢀ &:ꢀ Zꢁ<=>ꢁ<ꢀ 6&/ꢀ % +,&8ꢀ (%0**'%0ꢀ -3ꢀ ,PꢀGA5ꢀ.,ꢀSA5=ꢀ)-+ꢀ14-414I(ꢀ.8(ꢀ8:+2).4,-ꢀ.,ꢀG)'A5ꢀ)-+=ꢀ
5
#
+
06(0% +'%0ꢀ&:ꢀ%0 <+,&-ꢀ&-ꢀ;3=4ꢀ< + /2*+
(*>(54)'':=ꢀ.8(ꢀ4*,1(24I).4,-ꢀ.,ꢀT01A5CꢀT01A5ꢀ4*ꢀ6(2:ꢀ4-*,'0L'(ꢀ
!)L'(ꢀ;ꢀ*011)24*(*ꢀ.8(ꢀ2(*0'.*ꢀ,L.)4-(+ꢀZ4.8ꢀ.8(ꢀ&+F#ꢀ5).)':*.ꢀ )-+ꢀ5)-ꢀ5)0*(ꢀ>'0334-3ꢀ4**0(*ꢀ4-ꢀ)ꢀ8:>,.8(.45)'ꢀ)>>'45).4,-ꢀ4-ꢀ
Z8(-ꢀ58)-34-3ꢀ.8(ꢀTA5FGA5ꢀ1,'ꢀ2).4,=ꢀ4-4.4)'ꢀ>2(**02(*ꢀ,PꢀY
-+ꢀ2()5.4,-ꢀ.(1>(2).02(*Cꢀ!8(ꢀ2(*.ꢀ,Pꢀ.8(ꢀ2()5.4,-ꢀ5,-+4.4,-*ꢀ Y(<.=ꢀ.8(ꢀ(PP(5.ꢀ,PꢀY
Z(2(ꢀ.8,*(ꢀ,Pꢀ!)L'(ꢀBꢀ(<>(241(-.*CꢀT42*.ꢀ.82((ꢀ2,Z*ꢀ2(P(2ꢀ.,ꢀ.8(ꢀ (<>',2(+Cꢀ%-.24(*ꢀD=ꢀX=ꢀ[ꢀ)-+ꢀiꢀ*011)24I(*ꢀ.8(ꢀ2(*0'.*ꢀ5,-+05.(+ꢀ
PP(5.ꢀ,Pꢀ.8(ꢀTA5FGA5ꢀ1,'ꢀ2).4,Cꢀ]*4-3ꢀ)ꢀTA5FGA5ꢀ2).4,ꢀ5',*(ꢀ.,ꢀ ).ꢀ).1,*>8(245ꢀ>2(**02(=ꢀB7=ꢀD7ꢀ)-+ꢀ[7ꢀL)2CꢀS.)4-'(**ꢀ*.(('ꢀL).58ꢀ
Bꢀ4*ꢀ.8(ꢀL(*.ꢀ,>.4,-ꢀL(5)0*(ꢀ,Pꢀ.8(ꢀ*)64-3ꢀ4-ꢀTA5Cꢀ!8(ꢀ2(*0'.*ꢀ 2()5.,2ꢀ Z)*ꢀ 0*(+ꢀ P,2ꢀ (<>(241(-.*ꢀ ).ꢀ 8438ꢀ >2(**02(Cꢀ !8(ꢀ
'()2':ꢀ*8,Z(+ꢀ.8).ꢀ.8(ꢀ5,-6(2*4,-ꢀ,PꢀGA5ꢀ)-+ꢀ.8(ꢀ:4('+ꢀ,PꢀSA5ꢀ TA5FGA5ꢀZ)*ꢀe(>.ꢀ`ꢀBꢀL(5)0*(ꢀ,02ꢀ4-.(-.4,-ꢀ4*ꢀ.,ꢀ0*(ꢀ.8(ꢀ
(52()*(ꢀ 0>,-ꢀ ',Z(24-3ꢀ .8(ꢀ TA5ꢀ 5,-5(-.2).4,-Cꢀ !80*=ꢀ *.,4584,1(.245ꢀ2).4,Cꢀ"-52()*4-3ꢀ.8(ꢀ>2(**02(ꢀ2(*0'.*ꢀ4-ꢀ)ꢀ*1)''ꢀ
,-6(2*4,-ꢀ,PꢀGA5ꢀZ)*ꢀEi=ꢀaXꢀ)-+ꢀbBꢀ^ꢀ)-+ꢀ.8(ꢀ:4('+ꢀ,PꢀSA5ꢀZ)*ꢀ L0.ꢀ64*4L'(ꢀ(PP(5.ꢀ,-ꢀ.8(ꢀTA5ꢀ5,-6(2*4,-ꢀ)-+ꢀ.8(ꢀSA5ꢀ:4('+=ꢀ.8(ꢀ
Ei=ꢀb7ꢀ)-+ꢀX7ꢀ^ꢀP,2ꢀTA5FGA5ꢀ2).4,ꢀ,PꢀX=ꢀ;ꢀ)-+ꢀB=ꢀ2(*>(5.46(':=ꢀ ')..(2ꢀZ(-.ꢀ.82,038ꢀ)ꢀ1)<4101ꢀ).ꢀB7ꢀL)2ꢀQXEꢀ)-+ꢀ*1,,.8':ꢀ
'()2':ꢀ4-+45).4-3ꢀ.8).ꢀ.8(ꢀ2()5.4,-ꢀ2).(ꢀ,Pꢀ.2)-*P,21).4,-ꢀ,Pꢀ +(52()*(*ꢀP,2ꢀ')23(2ꢀ>2(**02(=ꢀ).ꢀ[7ꢀL)2ꢀ.8(ꢀSA5ꢀ:4('+ꢀZ)*ꢀXXꢀ^Cꢀ
GA5ꢀ4-.,ꢀSA5ꢀ)'*,ꢀ+(52()*(*CꢀU,Z(6(2=ꢀ)ꢀ>,*4.46(ꢀ2(*0'.ꢀ4*ꢀ.8).ꢀ ".ꢀ4*ꢀ41>,2.)-.ꢀ.,ꢀ-,.45(ꢀ.8).ꢀ.8(ꢀSA5ꢀ*('(5.464.:ꢀ4-ꢀTA5ꢀL)*4*ꢀZ(2(ꢀ
8(ꢀ*('(5.464.:ꢀ,PꢀSA5ꢀ4-ꢀTA5ꢀL)*4*ꢀP,2ꢀ2).4,*ꢀ,PꢀBꢀ)-+ꢀ;=ꢀZ)*ꢀ)'*,ꢀ 6(2:ꢀ8438ꢀ4-ꢀ)''ꢀ5)*(*ꢀQ)L,6(ꢀb[ꢀ^RCꢀS011)24I4-3=ꢀ>2(**02(ꢀ8)*ꢀ)ꢀ
O04.(ꢀ8438ꢀQaEꢀ)-+ꢀB77Cꢀ^=ꢀ2(*>(5.46(':R=ꢀ4-+45).4-3ꢀ.8).ꢀ.8(ꢀU ꢀ '414.(+ꢀ(PP(5.ꢀL(:,-+ꢀY ꢀ>2(**02(ꢀ,PꢀB7ꢀL)2C
,-.)4-(+ꢀ4-ꢀ.8(ꢀ5,-6(2.(+ꢀTA5ꢀ)'*,ꢀ(-+*ꢀ0>ꢀ(**(-.4)'':ꢀ4-ꢀSA5Cꢀ !8(ꢀ(PP(5.ꢀ,Pꢀ.8(ꢀ2()5.4,-ꢀ.(1>(2).02(ꢀ4*ꢀ+4*50**(+ꢀ-(<.ꢀQ(-.24(*ꢀ
-ꢀ,.8(2ꢀZ,2+*=ꢀTA5ꢀ0.4'4I).4,-ꢀZ)*ꢀ6(2:ꢀ(PP(5.46(ꢀ2(3)2+'(**ꢀ.8(ꢀ Xꢀ)-+ꢀbMERCꢀA*ꢀ(<>(5.(+=ꢀ.8(ꢀ2()5.4,-ꢀ.(1>(2).02(ꢀ8)*ꢀ)ꢀ>,*4.46(ꢀ
TA5FGA5ꢀ2).4,C (PP(5.ꢀ,-ꢀ.8(ꢀ5,-6(2*4,-ꢀ,Pꢀ2()5.)-.*ꢀL(5)0*(ꢀ.8(ꢀ2()5.4,-ꢀ2).(*ꢀ
;
ꢀ 5,-.4-0,0*ꢀ1,+(ꢀQG)'A5ꢀ4*ꢀ1058ꢀ1,2(ꢀ*,'0L'(RCꢀ
)
;
ꢀ>2(**02(ꢀ)-+ꢀ2()5.4,-ꢀ.(1>(2).02(ꢀZ)*ꢀ
(
5
+
5
5
.
;
;
5
"
!)L'(ꢀ;Cꢀ%PP(5.ꢀ,Pꢀ1)4-ꢀ6)24)L'(*ꢀ,Pꢀ,>(2).4,-ꢀ,-ꢀ.8(ꢀ5).)':.45ꢀ>2,>(2.4(*ꢀ,Pꢀ5,11(254)'ꢀ&+F#ꢀ5).)':*.Cꢀ#,11,-ꢀ
2
()5.4,-ꢀ5,-+4.4,-*ꢁꢀ[ꢀ3ꢀ,Pꢀ2()5.4,-ꢀ14<.02(=ꢀ[ꢀZ.C^ꢀGA5=ꢀBꢀZ.Cꢀ^ꢀ,Pꢀ5).)':*.=ꢀ)-+ꢀ.41(ꢀ,Pꢀ2()5.4,-ꢀXꢀ8C
TA5FGA5
&
4-CꢀY
;
ꢀ
wSA5ꢀQ^R
QS('SA5R5
%<>
!ꢀQ\#R
dGA5ꢀQ^R dTA5ꢀQ^R
wG)'A5ꢀQ^R wT01A5ꢀQ^R
Q1,'ꢀ2).4,R
QL)2R)
Ei
QB77R
b7
B
;
D
X
[
i
b
a
E
X
;
B
B
B
B
B
B
B
B
BB7
BB7
BB7
BB7
BB7
BB7
BD7
BX7
B[7
B[7
).1CL
EE
aX
bB
bD
b[
iE
EB
Eb
EE
B77
;X
D[
X[
i7
iB
[;
bE
ab
E7
Ea
B
B
D
).1C
).1C
B7
B;
BB
BB
BB
B;
B;
X
QB77R
X7
B
QaER
XE
B
Qa;R
Xb
D7
;
QbbR
XX
[7
B
Qa[R
ib
B7
D
Qa[R
ab
B7
i
QB77R
aD
B7
B7
7
X
QE;R
Eaꢀ
B7+
)ꢀ
B7
;
QB77R
"-4.4)'ꢀ>2(**02(ꢀ,PꢀY
;
C
Lꢀ).1Cꢁꢀ).1,*>8(245ꢀ>2(**02(
5ꢀS('(5.464.:ꢀ,PꢀSA5ꢀL)*(+ꢀ,-ꢀTA5
+ꢀ
;
]*4-3ꢀ*,+401ꢀP,21).(ꢀ)*ꢀU ꢀ*,025(CꢀS)1(ꢀ5,-+4.4,-*ꢀ)*ꢀ(-.2:ꢀE=ꢀ(<5(>.ꢀ;ꢀ8ꢀ,Pꢀ2()5.4,-ꢀ.41(
"
.ꢀ4*ꢀ)'*,ꢀZ,2.8ꢀ-,.454-3ꢀ.8).ꢀ.8(ꢀ:4('+ꢀ,PꢀT01A5ꢀ)'*,ꢀ4-52()*(*ꢀ L(5,1(ꢀ P)*.(2Cꢀ !80*=ꢀ .8(ꢀ :4('+ꢀ ,Pꢀ SA5ꢀ 4-52()*(*ꢀ Z4.8ꢀ
>,-ꢀ+(52()*4-3ꢀ.8(ꢀ2).4,ꢀQP2,1ꢀDꢀP,2ꢀ)ꢀ2).4,ꢀ,PꢀXꢀ.,ꢀBBꢀP,2ꢀ',Z(2ꢀ .(1>(2).02(ꢀ)-+ꢀ2()58(+ꢀ6)'0(*ꢀZ(''ꢀ)L,6(ꢀa7ꢀ^ꢀP,2ꢀBX7ꢀ)-+ꢀ
).4,*RCꢀS,ꢀ4.ꢀ*((1*ꢀ.8).ꢀZ8(-ꢀZ,2e4-3ꢀZ4.8ꢀ',ZꢀTA5FGA5ꢀ2).4,=ꢀ B[7ꢀ\#Cꢀ"-.(2(*.4-3':=ꢀ.8(ꢀ:4('+ꢀ,PꢀT01A5ꢀ+(52()*(*ꢀ)'*,ꢀZ4.8ꢀ
0
2
GA5ꢀ4*ꢀ-,.ꢀ2)>4+':ꢀ8:+2,3(-).(+ꢀ.,ꢀSA5ꢀ)-+ꢀ4*ꢀ4*,1(24I(+ꢀ.,ꢀ .(1>(2).02(Cꢀ U,Z(6(2=ꢀ .8(ꢀ 4-52()*(ꢀ ,Pꢀ .8(ꢀ 2()5.4,-ꢀ
T01A5Cꢀ!8(ꢀ*)1(ꢀ5)-ꢀ)'*,ꢀ,5502*=ꢀ4-ꢀ)ꢀ'(**ꢀ(<.(-*4,-=ꢀZ4.8ꢀ
!
84*ꢀ/,02-)'ꢀ4*ꢀoꢀ!8(ꢀ ,:)'ꢀS,54(.:ꢀ,Pꢀ#8(14*.2:ꢀ;7<<
HVꢀX 60C=ꢀ;7BD=ꢀꢁꢁ=ꢀBMDꢀnꢀQ
&
'()*(ꢀ+,ꢀ-,.ꢀ)+/0*.ꢀ1)234-*

Green Chemistry
Page 6 of 14
View Article Online
DOI: 10.1039/C9GC04221K

Page 7 of 14
Green Chemistry
View Article Online
DOI: 10.1039/C9GC04221K

Green Chemistry
Page 8 of 14
View Article Online
DOI: 10.1039/C9GC04221K

Page 9 of 14
Green Chemistry
View Article Online
DOI: 10.1039/C9GC04221K

&
'()*( Gꢀ +r ,e ꢀe- n, C. ꢀ h) +e /m0 *i s. tꢀ 1r y)234-*
Page 10 of 14
View Article Online
;!7#+ꢀQ8ꢀ ()5.4,-ꢀ2).(ꢀ,Pꢀ5,-6(2*4,-ꢀ,PꢀTA5ꢀ4-ꢀ.8(ꢀ)L -5(ꢀ,
DOI: 10.1039/ C* (9 GC04 2P ꢀ2 1K
GA5
A:;9 <=
GA5ꢀQ2TA5Rꢀ6*Cꢀ.8(ꢀ2).(ꢀ,Pꢀ5,-6(2*4,-ꢀ,PꢀTA5ꢀQ2T A> .
5
2'(
P,21).4,-ꢀ ,Pꢀ SAꢀ Q2SA5 Rꢀ Z8(-ꢀ GA5ꢀ 4*ꢀ >2(*(-.ꢀ Q2).(*ꢀ
! ?!0+
Rꢀ )# ꢀ- +ꢀ,Pꢀ
GA5
(
<>2(**(+ꢀ)*ꢀ11,'c35).MBc14-MBR
,
!'!&"+'%C!"%.(ꢀ.*ꢀ",+ꢀ*'+),ꢀ!(-ꢀ2)+-ꢀO-P ꢀ&!"!#$)")8
4-ꢀ.8(ꢀ)L*(-5(ꢀ,Pꢀ
GA5)
4
-ꢀ.8(ꢀ>2(*(-5(ꢀ,PꢀGA5L
!
8(ꢀ&+ꢀ5,-.(-.ꢀQ&+ꢀZ.Cꢀ^Rꢀ,Pꢀ.8(ꢀP2(*8ꢀ)-+ꢀ0*(+ꢀ5).)':*.ꢀ
Q+,Z-',)+(+ꢀP2,1ꢀ.8(ꢀ2()5.,2ꢀ)P.(2ꢀ.8(ꢀ(<>(241(-.*ꢀ,PꢀT4302(ꢀ
bRꢀZ)*ꢀXCEbꢀvꢀ7CX[ꢀ)-+ꢀXCbXꢀvꢀ7CX;=ꢀ2(*>(5.46(':Cꢀg,.8ꢀ6)'0(*ꢀ)2(ꢀ
2TA5
2TA5GA5
2SA5GA5
U#@@
U
BC7iꢀvꢀ7C7B
7CEBꢀvꢀ7C7;
7C[bꢀvꢀ7C7B
7CDaꢀvꢀ7C7B
7C[Eꢀvꢀ7C7B
7CDaꢀvꢀ7C7;
;!7#+ꢀE8ꢀ?4*>(2*4,-ꢀ)-+ꢀ&+ꢀ>)2.45'(ꢀ*4I(ꢀ4-ꢀP2(*8ꢀ)-+ꢀ0*(+ꢀ
?#@@U
5
).)':*.ꢀ1()*02(+ꢀL:ꢀ#@ꢀ58(14*,2>.4,-ꢀ)-+ꢀ!%G
)ꢀ
,
Y,ꢀGA5ꢀZ)*ꢀ4-5,2>,2).(+ꢀP,2ꢀ.8(ꢀ+(.(214-).4,-ꢀ,Pꢀ.8(ꢀ2).(ꢀ
Pꢀ+42(5.ꢀ+(5,1>,*4.4,-ꢀ,PꢀTA5
Lꢀ ()5.4,-ꢀ5,-+4.4,-*ꢁꢀ[ꢀ3ꢀ,Pꢀ2()5.4,-ꢀ14<.02(=ꢀ[ꢀZ.C^ꢀGA5=ꢀ
#@ꢀ58(14*,2>.4,-
!%Gꢀ*.0+4(*
?
4*>(2*4,-)ꢀ
Q^R
S4I(ꢀ
Q-1R
?4*>(2*4,-ꢀ
Q^R
S4I(Lꢀ
Q-1R
7
C[ꢀZ.C^ꢀ,Pꢀ5).)':*.=ꢀ1,'ꢀTA5FGA5ꢀ`ꢀB=ꢀB[7ꢀ\#=ꢀ4-4.4)'ꢀY
2(**02(ꢀ`ꢀB7ꢀL)2=ꢀ.41(ꢀ,Pꢀ2()5.4,-ꢀBꢀ8
;
ꢀ
>
;
C;ꢀvꢀ
CB
DCiꢀvꢀ
CD
DCD[vꢀ
7C7[
P2(*8
[BCiꢀvꢀ;CD
DBCBꢀvꢀ;Ca
DDCXvꢀ7C[
BaCbvꢀ7CX
7
iC77vꢀ
7CB;
=
D4+'%0+("!#ꢀ+6%-+(&+)ꢀ.*ꢀ ;Xꢀ0+&,!(%)0
-ꢀ>24-54>'(=ꢀ.Z,ꢀ2,0.(*ꢀ5)-ꢀL(ꢀ>2,>,*(+ꢀZ8(-ꢀTA5ꢀ4*ꢀ0*(+ꢀ)*ꢀ
8(ꢀ2(+05.4,-ꢀ)3(-.ꢀP,2ꢀ.8(ꢀ8:+2,3(-).4,-ꢀ2()5.4,-CꢀAꢀP42*.ꢀ
>.4,-ꢀ4*ꢀ.8).ꢀ.8(ꢀ2()5.4,-ꢀ>2,5((+*ꢀ.82,038ꢀ)ꢀ5,-5(2.(+ꢀ#!Uꢀ
(58)-4*1ꢀ4-ꢀZ8458ꢀUꢀ).,1*ꢀ4-ꢀ.8(ꢀP,2145ꢀ)54+ꢀ)2(ꢀ+42(5.':ꢀ
2)-*P(22(+ꢀ.,ꢀ.8(ꢀ+,0L'(ꢀL,-+ꢀ,PꢀGA5CꢀA-,.8(2ꢀ,>.4,-ꢀ4*ꢀ.8).ꢀ
P,2145ꢀ)54+ꢀ+(5,1>,*(*ꢀ,6(2ꢀ.8(ꢀ*02P)5(ꢀ,Pꢀ.8(ꢀ5).)':*.ꢀ:4('+4-3ꢀ
)*ꢀ#@ ꢀ)-+ꢀ.8(ꢀU).,1*ꢀQ(4.8(2ꢀ)*ꢀ3)*ꢀU ꢀ,2ꢀ)*ꢀ)+*,2L(+ꢀ,-ꢀ.8(ꢀ
+ꢀ*02P)5(Rꢀ-((+(+ꢀP,2ꢀ.8(ꢀGA5ꢀ8:+2,3(-).4,-C
W8(-ꢀ.8(ꢀ8:+2,3(-).4,-ꢀZ)*ꢀ5,-+05.(+ꢀ0*4-3ꢀ3)*ꢀU
0*(+
7
"
)ꢀ+
4*>(2*4,-ꢀ)-+ꢀ>)2.45'(ꢀ*4I(ꢀQ+4)1(.(2ꢀ4-ꢀ-1Rꢀ4-ꢀ&+ꢀ)2(ꢀ
.
2
(').(+ꢀL:ꢀ(O0).4,-ꢀ*4I(ꢀ+ꢀ`ꢀBCB;F+4*>(2*4,-ꢀDiC
,
Lꢀ>)2.45'(ꢀ*4I(ꢀ(*.41).(+ꢀL:ꢀ!%GꢀZ)*ꢀ5)'50').(+ꢀ)*ꢀ.8(ꢀ1()-ꢀ
1
D
4 4
F#-+
;Rꢀ,L.)4-(+ꢀP2,1ꢀ.8(ꢀ*02P)5(ꢀ
*
02P)5(ꢀ+4)1(.(2ꢀQ#-
4
+
4
.
4 4 4
4*.24L0.4,-ꢀ,Pꢀ>)2.45'(*ꢀQ-+ Rꢀ CꢀS((ꢀ%S"ꢀ*(5.4,-ꢀP,2ꢀ
;ꢀ6*Cꢀ+
Di
+
2
(>2(*(-.).46(ꢀ>45.02(*ꢀ)-+ꢀP02.8(2ꢀ+(.)4'*ꢀ,Pꢀ!%Gꢀ*.0+4(*C
3
;
ꢀ
;
&
*
414')2ꢀZ4.84-ꢀ.8(ꢀ(<>(241(-.)'ꢀ(22,2Cꢀ!8(ꢀ&+ꢀ5,-5(-.2).4,-ꢀ,Pꢀ
;
ꢀ).ꢀ)ꢀ
2(**02(ꢀ(O0)'ꢀ.,ꢀ.8(ꢀ>2(**02(ꢀ.8).ꢀZ,0'+ꢀL(ꢀ3(-(2).(+ꢀL:ꢀ.8(ꢀ
(5,1>,*4.4,-ꢀ,Pꢀ.8(ꢀP,2145ꢀ)54+ꢀ4.ꢀZ)*ꢀP,0-+ꢀ.8).ꢀ.8(ꢀU M3)*ꢀ
.
8(ꢀ)O0(,0*ꢀ*,'0.4,-*ꢀ*)1>'(+ꢀ+024-3ꢀ.8(ꢀ*.0+:ꢀ,PꢀT4302(ꢀS?Miꢀ
>
+
Z)*ꢀ4-ꢀ)''ꢀ5)*(*ꢀL(',Zꢀ7C7;ꢀ13F$=ꢀ.8(ꢀ+(.(5.4,-ꢀ'414.ꢀ,Pꢀ.8(ꢀ
(58-4O0(CꢀA**014-3ꢀ.8).ꢀ.8(ꢀ&+ꢀ5,-5(-.2).4,-ꢀ4-ꢀ.8(ꢀ*)1>'(*ꢀ
;
.
2
()5.4,-ꢀ2).(ꢀ4*ꢀ*',Z(2ꢀ.8)-ꢀ.8).ꢀ0*4-3ꢀP,2145ꢀ)54+ꢀQ*((ꢀT43CꢀS?Miꢀ
-+ꢀ+4*50**4,-ꢀ.8(2(4-RCꢀ!84*ꢀ2(*0'.ꢀ*033(*.*ꢀ.8).ꢀ.8(ꢀ2()5.4,-ꢀ
,(*ꢀ -,.ꢀ 5,1>'(.(':ꢀ >2,5((+ꢀ 64)ꢀ U ꢀ 2('()*(+ꢀ P2,1ꢀ .8(ꢀ
(5,1>,*4.4,-ꢀ,PꢀP,2145ꢀ)54+Cꢀ!84*ꢀ(<>(241(-.ꢀ4*ꢀ-,.ꢀ5,-5'0*46(Cꢀ
Z)*ꢀ7C7;ꢀ13F$=ꢀ'(**ꢀ.8)-ꢀ7CDiꢀ^ꢀ,Pꢀ.8(ꢀ.,.)'ꢀ&+ꢀ4-4.4)'':ꢀ',)+(+ꢀ
)
4
-ꢀ.8(ꢀP2(*8ꢀ5).)':*.ꢀZ,0'+ꢀ8)6(ꢀL((-ꢀ'()58(+ꢀ+024-3ꢀ.8(ꢀDb7ꢀ8ꢀ
+
+
;
,
-ꢀ*.2()1Cꢀ!80*=ꢀ&+ꢀ'()584-3ꢀ5)-ꢀL(ꢀ5,-*4+(2(+ꢀ422('(6)-.C
!8(ꢀ+4*>(2*4,-ꢀ)-+ꢀ.8(ꢀ)6(2)3(ꢀ+4)1(.(2ꢀ,Pꢀ.8(ꢀ&+ꢀ>)2.45'(*ꢀ4-ꢀ
G,2(ꢀ5,1>(''4-3ꢀ(64+(-5(*ꢀP,2ꢀ0-6(4'4-3ꢀ.8(ꢀ1(58)-4*1ꢀ)2(ꢀ
.
8(ꢀP2(*8ꢀ)-+ꢀ0*(+ꢀ&+F#ꢀ5).)':*.*ꢀ)2(ꢀ*011)24I(+ꢀ4-ꢀ!)L'(ꢀXCꢀ
+
(+05(+ꢀP2,1ꢀ4*,.,>45ꢀ(<>(241(-.*C
)L'(ꢀ[ꢀ*011)24I(*ꢀ.8(ꢀ4*,.,>45ꢀe4-(.45ꢀ(<>(241(-.*Cꢀ!8(ꢀ2).(*ꢀ
Pꢀ5,-6(2*4,-ꢀ,PꢀTAꢀQ2TA5Rꢀ4-ꢀ.8(ꢀ)L*(-5(ꢀ,PꢀGA5=ꢀ0*4-3ꢀP,2145ꢀ
54+ꢀQU#@@URꢀ)-+ꢀ+(0.(2).(+ꢀP,2145ꢀ)54+ꢀ4-ꢀ.8(ꢀP,21:'ꢀ>,*4.4,-ꢀ
Q?#@@URꢀ)2(ꢀ4-5'0+(+Cꢀ!84*ꢀ2()5.4,-ꢀ2(>2(*(-.*ꢀ.8(ꢀ+42(5.ꢀ
!
8(ꢀ0*(+ꢀ&+F#ꢀ*)1>'(ꢀ5,22(*>,-+*ꢀ.,ꢀ.8).ꢀ,PꢀT43CꢀbCꢀ!)L'(ꢀXꢀ
!
3
46(*ꢀ.8(ꢀ4-P,21).4,-ꢀ,L.)4-(+ꢀP2,1ꢀ.Z,ꢀ+4PP(2(-.ꢀ.(58-4O0(*ꢁꢀ
,
#
@ꢀ 58(14*,2>.4,-ꢀ )-+ꢀ !%Gꢀ *.0+4(*ꢀ Q*((ꢀ T43Cꢀ S?M[ꢀ P,2ꢀ
)
2
(>2(*(-.).46(ꢀ!%Gꢀ>45.02(*RCꢀg,.8ꢀ.(58-4O0(*ꢀ5,-P421ꢀ.8).ꢀ.8(ꢀ
&
+ꢀ>)2.45'(*ꢀ0-+(2.)e(ꢀ)ꢀ*4-.(24-3ꢀ+024-3ꢀ.8(ꢀ5).)':*.ꢀ0.4'4I).4,-Cꢀ
@ꢀ58(14*,2>.4,-ꢀ*8,Z*ꢀ.8).ꢀ.8(ꢀ)6(2)3(ꢀ>)2.45'(ꢀ*4I(ꢀ4-52()*(*ꢀ
+
(5,1>,*4.4,-ꢀ,PꢀTA5=ꢀ4-.,ꢀ3)*ꢀ#@
; ;
ꢀ)-+ꢀUꢀ).,1*ꢀQ,2ꢀ3)*ꢀU RCꢀ
#
!
8(*(ꢀ2).(*ꢀ)2(ꢀ5,1>)2(+ꢀZ4.8ꢀ.8(ꢀTA5ꢀ5,-6(2*4,-ꢀ4-ꢀ.8(ꢀ
GA5
P2,1ꢀ;C;ꢀ.,ꢀDCiꢀ-1ꢀ)-+ꢀ!%GꢀP2,1ꢀDCD[ꢀ.,ꢀiC77=ꢀZ8(2()*ꢀ.8(ꢀ
>
2(*(-5(ꢀ,PꢀGAꢀQ2TA5 Rꢀ)-+ꢀZ4.8ꢀ.8(ꢀ2).(ꢀ,PꢀP,21).4,-ꢀ,PꢀSA5ꢀ
GA5
+
4*>(2*4,-ꢀ(*.41).(+ꢀP2,1ꢀ#@ꢀ58(14*,2>.4,-ꢀ58)-3(*ꢀP2,1ꢀ[BCiꢀ
Q2SA5 RCꢀ
.
,ꢀDBCBꢀ^ꢀ)-+ꢀ.8).ꢀ,Pꢀ!%Gꢀ*.0+4(*ꢀP2,1ꢀDDCXꢀ.,ꢀBaCbꢀ^Cꢀ"-ꢀ
GA5
T42*.=ꢀZ(ꢀ5,1>)2(ꢀ2SA5 ꢀ0*4-3ꢀ(4.8(2ꢀP,2145ꢀ)54+ꢀQU#@@URꢀ,2ꢀ
3
(-(2)'=ꢀ>)2.45'(ꢀ*4I(*ꢀ(*.41).(+ꢀL:ꢀ!%Gꢀ*.0+4(*ꢀ)2(ꢀ)'Z):*ꢀ
+
(0.(2).(+ꢀ?#@@UꢀQ')*.ꢀ5,'01-ꢀ,Pꢀ.8(ꢀ!)L'(ꢀ[RCꢀ!8(ꢀ2).(ꢀ
GA5
')23(2ꢀ.8)-ꢀ.8).ꢀ,L.)4-(+ꢀP2,1ꢀ#@ꢀ58(14*,2>.4,-ꢀL(5)0*(ꢀ,Pꢀ
2
SA5 ꢀZ4.8ꢀU#@@Uꢀ4*ꢀP)*.(2ꢀ.8)-ꢀ.8).ꢀZ4.8ꢀ?#@@UꢀQ7C[Eꢀ6*Cꢀ
MB
.
8(ꢀ+4PP450'.:ꢀ.,ꢀ)55,0-.ꢀP,2ꢀ>)2.45'(*ꢀZ4.8ꢀ*4I(*ꢀ4-ꢀ.8(ꢀ2)-3(ꢀ,PꢀBꢀ
MB
7
CDaꢀ11,'ꢀSA5c35). c14- =ꢀ2(*>(5.46(':RCꢀ!8(ꢀ2).4,ꢀL(.Z((-ꢀ
-
1ꢀ)-+ꢀ*1)''(2Cꢀg(*4+(*=ꢀ*,1(ꢀ,Pꢀ')23(2ꢀ>)2.45'(*ꢀZ(2(ꢀ.8(ꢀ
.
8(*(ꢀ2).(*ꢀ4*ꢀBC[[ꢀvꢀ7C7bꢀ(64+(-54-3ꢀ.8).ꢀ.8(2(ꢀ4*ꢀ)ꢀe4-(.45ꢀ
*,.,>(ꢀ(PP(5.ꢀ4-ꢀ.8(ꢀP,21).4,-ꢀ,PꢀSA5Cꢀ!8(ꢀ*)1(ꢀ(PP(5.ꢀ4*ꢀP,0-+ꢀ
2(*0'.ꢀ,Pꢀ.8(ꢀ)33',1(2).4,-ꢀ,Pꢀ*(6(2)'ꢀ&+ꢀ>)2.45'(*ꢀ)-+ꢀ5)-ꢀ
4
-)+6(2.(-.':ꢀ L(ꢀ )55,0-.(+ꢀ )*ꢀ ,-':ꢀ ,-(ꢀ >)2.45'(Cꢀ @-ꢀ .8(ꢀ
4
GA5
Z8(-ꢀ5,1>)24-3ꢀ2TA5 ꢀ0*4-3ꢀU#@@Uꢀ)-+ꢀ?#@@UꢀQ7C[bꢀ6*Cꢀ
5
,-.2)2:ꢀ#@ꢀ58(14*,2>.4,-ꢀ5)-ꢀ+4PP(2(-.4).(ꢀ.8(*(ꢀ4-+464+0)'ꢀ
MB
MB
7
CDaꢀ11,'ꢀTA5c35). c14- RCꢀ"-ꢀ5,-.2)*.=ꢀ.8(ꢀ2).4,ꢀL(.Z((-ꢀ.8(ꢀ
).(*ꢀ,Pꢀ+42(5.ꢀ+(5,1>,*4.4,-ꢀQ2TA5ꢀRꢀ,PꢀU#@@Uꢀ)-+ꢀ?#@@Uꢀ4*ꢀ
BCBiꢀvꢀ7C7;ꢀQBC7iꢀ+464+(+ꢀL:ꢀ7CEBRCꢀ!84*ꢀ2).4,ꢀ4*ꢀ',Z(2ꢀ.8)-ꢀ.8(ꢀ
>
)2.45'(*ꢀL(5)0*(ꢀ4.ꢀ.4.2).(*ꢀ)'1,*.ꢀ)''ꢀ.8(ꢀ*02P)5(ꢀ).,1*ꢀ(<5(>.ꢀ
2
.
.
8,*(ꢀP(Zꢀ4-ꢀ.8(ꢀ5,-.)5.4-3ꢀ2(34,-ꢀ,Pꢀ.8(ꢀ4-+464+0)'ꢀ>)2.45'(*ꢀ,Pꢀ
8(ꢀ)33',1(2).(Cꢀ"-ꢀ)-:ꢀ5)*(ꢀL,.8ꢀ.(58-4O0(*ꢀ8)6(ꢀ,L*(26(+ꢀ)ꢀ
GA5
GA5
2
).4,ꢀP,2ꢀ2TA5 ꢀ)-+ꢀ2SA5 ꢀQBC[[ꢀ6*CꢀBCBiRCꢀ!8(*(ꢀ2(*0'.*ꢀ
-+45).(=ꢀ P42*.=ꢀ .8).ꢀ P,2145ꢀ )54+ꢀ 4*ꢀ 4-6,'6(+ꢀ 4-ꢀ .8(ꢀ 2).(ꢀ
(.(214-4-3ꢀ*.(>ꢀ,Pꢀ.8(ꢀSA5ꢀP,21).4,-=ꢀ1,2(ꢀ*>(54P45)'':=ꢀP,21:'ꢀ
Uꢀ4*ꢀ4-6,'6(+CꢀS(5,-+=ꢀ.8).ꢀ.8(ꢀ+42(5.ꢀ+(5,1>,*4.4,-ꢀ,PꢀP,2145ꢀ
54+ꢀ.,ꢀUꢀ).,1*ꢀ4*ꢀ-,.ꢀ4-6,'6(+ꢀ4-ꢀ.8(ꢀ2).(ꢀ+(.(214-4-3ꢀ*.(>ꢀ,Pꢀ
BCiMBCaꢀP,'+ꢀ4-52()*(ꢀ,Pꢀ.8(ꢀ>)2.45'(*ꢀ*4I(ꢀ)-+ꢀ)ꢀ7CiꢀP,'+ꢀ2(+05.4,-ꢀ
4
4-ꢀ.8(ꢀ+4*>(2*4,-ꢀ,Pꢀ.8(ꢀ>)2.45'(*C
+
)
.
8(ꢀ8:+2,3(-).4,-ꢀ2()5.4,-=ꢀ,.8(2Z4*(ꢀ.8(ꢀ*)1(ꢀ4*,.,>45ꢀ(PP(5.ꢀ
SꢁꢀnꢀHVꢀX 60C=ꢀ;7B;=ꢀꢁꢁ=ꢀBMD
!84*ꢀ/,02-)'ꢀ4*ꢀoꢀ!8(ꢀ ,:)'ꢀS,54(.:ꢀ,Pꢀ#8(14*.2:ꢀ;7<<
&
'()*(ꢀ+,ꢀ-,.ꢀ)+/0*.ꢀ1)234-*

Page 11 of 14
&'()*( Gꢀ +r ,e ꢀe- n, C. ꢀ h) +e /m0 *i s. tꢀ 1r y)234-*
View Article Online
DOI: 10.1039/C9GC04221K
>.2'(!#ꢀ?!0+
ꢀA:;9 <=
5
GA5
Z,0'+ꢀ8)6(ꢀL((-ꢀ,L*(26(+ꢀP,2ꢀ2TA5ꢀ)-+ꢀ2TA5 Cꢀ#,-*(O0(-.':=ꢀ 8:+2,3(-).4,-ꢀ,Pꢀ#`#ꢀ)-+ꢀ#`@ꢀL,-+*ꢀ4-ꢀ'4O04+ꢀ>8)*(ꢀ,-ꢀ&+ꢀ
8(ꢀ2).(ꢀ+(.(214-4-3ꢀ*.(>ꢀ8)*ꢀ.,ꢀ4-6,'6(ꢀ.8(ꢀ5,-5(2.(+ꢀ)-+ꢀ 5).)':*.*ꢀ8)6(ꢀ)'2()+:ꢀL((-ꢀ+(1,-*.2).(+ꢀXBC
42(5.ꢀ.2)-*P(2(-5(ꢀ,PꢀUꢀ).,1*ꢀP2,1ꢀTA5ꢀ.,ꢀ1)'(45ꢀ)54+C
A++4.4,-)'ꢀ *0>>,2.ꢀ .,ꢀ .8(*(ꢀ 5,-5'0*4,-*ꢀ 5,1(*ꢀ P2,1ꢀ .8(ꢀ Aꢀ4'+#%0%(!'$ꢀ!))+))0+("ꢀ.*ꢀ",+ꢀ+(6%'.(0+("!#ꢀ%04!&"5ꢀ X;ꢀ
,1>)24*,-ꢀ L(.Z((-ꢀ .8(ꢀ 2(*0'.*ꢀ P2,1ꢀ .8(ꢀ *)1(ꢀ 2,ZCꢀ *'.0ꢀ*.'0%&ꢀ!&%-ꢀ6)8ꢀX ꢀ/!)ꢀ,$-'./+(!"%.(
-.(2(*.4-3':=ꢀZ8(-ꢀ5,1>)24-3ꢀ.8(ꢀ2).(*ꢀZ4.84-ꢀ.8(ꢀ*)1(ꢀP42*.ꢀ !8(ꢀ #!Uꢀ )>>2,)58ꢀ 4-6,'6(*ꢀ *,1(ꢀ P().02(*ꢀ .8).ꢀ 5,0'+ꢀ
.
+
5
@
"
2
2
,Zꢀ,Pꢀ(<>(241(-.*ꢀQ(<>(241(-.*ꢀ0*4-3ꢀU#@@URꢀZ(ꢀP,0-+ꢀ.8).ꢀ *43-4P45)-.':ꢀ41>2,6(ꢀ.8(ꢀ*0*.)4-)L4'4.:ꢀ,Pꢀ.8(ꢀSA5ꢀ>2,+05.4,-ꢀ)*ꢀ
GA5
TA5ꢀ4*ꢀ)'1,*.ꢀ.Z,ꢀ.41(*ꢀP)*.(2ꢀ.8)-ꢀ2TA5 ꢀQBC7iꢀ6*Cꢀ7C[bꢀ11,'ꢀ 5,1>)2(+ꢀ.,ꢀ.8(ꢀ5,-6(-.4,-)'ꢀ>(.2,58(145)'ꢀZ):Cꢀ"-ꢀ>)2.450')2=ꢀ
MB
MB
GA5
MB
MB
TA5c35). c14- Rꢀ)-+ꢀ2SA5 ꢀQ7C[Eꢀvꢀ7C7Bꢀ11,'ꢀSA5c35). c14- RCꢀ 0*4-3ꢀTA5ꢀ)*ꢀ)ꢀ2(+05.4,-ꢀ)3(-.ꢀ)6,4+*ꢀ*.,24-3ꢀ)-+ꢀ8)-+'4-3ꢀU
8(ꢀ*)1(ꢀ,5502*ꢀZ8(-ꢀ5,1>)24-3ꢀ.8(ꢀ2).(*ꢀ,Pꢀ.8(ꢀ*(5,-+ꢀ2,Zꢀ 8438ꢀ>2(**02(=ꢀ)-+ꢀ.80*ꢀ.84*ꢀ>2,L)L':ꢀ5,-*.4.0.(*ꢀ,-(ꢀ,Pꢀ.8(ꢀ
Z8(-ꢀ.8(ꢀ2()5.4,-ꢀ4*ꢀ5,-+05.(+ꢀZ4.8ꢀ?#@@UꢀQ7CEBꢀvꢀ7C7;ꢀ6*Cꢀ 1,*.ꢀ >2,14*4-3ꢀ )+6)-.)3(*ꢀ .,ꢀ )584(6(ꢀ )ꢀ 32((-(2ꢀ >2,5(**Cꢀ
;
ꢀ).ꢀ
!
GA5ꢀ
7
CDaꢀvꢀ7C7BRCꢀ".ꢀ4*ꢀ)'*,ꢀZ,2.8ꢀ-,.454-3ꢀ.8).ꢀ2TA5 4*ꢀ*414')2ꢀ.,ꢀ U,Z(6(2=ꢀ)-ꢀ(6)'0).4,-ꢀ,Pꢀ.8(ꢀ(-642,-1(-.)'ꢀ41>)5.*ꢀ5)0*(+ꢀ
GA5
2
SA5 =ꢀZ8).ꢀ1()-*ꢀ.8).ꢀTA5ꢀ+(5,1>,*4.4,-ꢀ)-+ꢀSA5ꢀP,21).4,-ꢀ L:ꢀ.8(*(ꢀ.Z,ꢀ)'.(2-).46(*ꢀQ0*4-3ꢀTA5ꢀ,2ꢀ8438M>2(**02(ꢀU
;
Rꢀ4*ꢀ
2(ꢀ4-.41).(':ꢀ5,0>'(+ꢀ)-+ꢀ.8).ꢀZ8(-ꢀGA5ꢀ4*ꢀ>2(*(-.ꢀ.8(ꢀ2).(ꢀ 1)-+).,2:ꢀ .,ꢀ )584(6(ꢀ )ꢀ 5',*(2ꢀ 0-+(2*.)-+4-3ꢀ ,Pꢀ .8(ꢀ
PꢀP,2145ꢀ)54+ꢀ5,-*01>.4,-ꢀ4*ꢀ'414.(+ꢀL:ꢀ.8(ꢀP,21).4,-ꢀ,PꢀSA5=ꢀ 41>2,6(1(-.*ꢀ4-ꢀ.8(ꢀ*0*.)4-)L4'4.:ꢀ,PꢀSA5ꢀ>2,+05.4,-ꢀ.8).ꢀ1):ꢀ
-ꢀ,.8(2ꢀZ,2+*=ꢀTA5ꢀ4*ꢀ,-':ꢀ5,-6(2.(+ꢀ,-5(ꢀSA5ꢀ4*ꢀP,21(+Cꢀ!8(*(ꢀ L(ꢀ)55,1>'4*8(+ꢀL:ꢀ41>'(1(-.4-3ꢀ)ꢀ#!Uꢀ.2)-*P,21).4,-ꢀ>).8Cꢀ
(*0'.*ꢀ)2(ꢀ4-ꢀ)32((1(-.ꢀZ4.8ꢀ)ꢀ2).(ꢀ+(.(214-4-3ꢀ*.(>ꢀ4-6,'64-3ꢀ $4P(ꢀ #:5'(ꢀ A**(**1(-.ꢀ Q$#ARꢀ 4*ꢀ )ꢀ Z(''Me-,Z-=ꢀ Z4+(':ꢀ 0*(+ꢀ
ꢀ#!Uꢀ1(58)-4*1C 1(.8,+,',3:ꢀ P,2ꢀ O0)-.4P:4-3ꢀ .8(ꢀ (-642,-1(-.)'ꢀ 41>)5.*ꢀ
S>(-5(2ꢀ).ꢀ)'C ꢀ8)6(ꢀ)'*,ꢀ5,-5'0+(+ꢀ.8).ꢀ.8(ꢀ8:+2,3(-).4,-ꢀ,Pꢀ )*524L(+ꢀ.,ꢀ4-+0*.24)'ꢀ*:*.(1*=ꢀ4-5'0+4-3ꢀ.8(ꢀ*.(>*ꢀL(:,-+ꢀ.8(ꢀ
M#ꢀ0-*).02).(+ꢀL,-+*ꢀ0*4-3ꢀTA5ꢀ)*ꢀ2(+05.4,-ꢀ)3(-.ꢀ)-+ꢀ&+F#ꢀ P)5.,2:ꢀ3).(=ꢀ.8).ꢀ4*=ꢀ0-+(2*.)-+4-3ꢀ.8(ꢀP0''ꢀ'4P(ꢀ5:5'(ꢀ,Pꢀ)ꢀ
)
,
4
2
)
X7
#
X;
)
*ꢀ5).)':*.ꢀ,>(2).(*ꢀ64)ꢀ)ꢀ#!Uꢀ1(58)-4*1Cꢀ"-ꢀ.8(42ꢀ5)*(ꢀ)-ꢀ >2,+05.ꢀ,2ꢀ>2,5(** Cꢀ#,1>'(.4-3ꢀ)-ꢀ$#Aꢀ*.0+:ꢀ4*ꢀ)ꢀ5,1>'(<ꢀ.)*eꢀ
'e:-(ꢀQ1(.8:'ꢀ>8(-:'>2,>4,').(RꢀZ)*ꢀ8:+2,3(-).(+ꢀ.,ꢀ.8(ꢀ L(5)0*(ꢀ,Pꢀ.8(ꢀ32().ꢀ)1,0-.ꢀ,Pꢀ4-P,21).4,-ꢀ.8).ꢀ10*.ꢀL(ꢀ
)
5
,22(*>,-+4-3ꢀ 54*M)'e(-(ꢀ 0*4-3ꢀ .241(.8:')14-(ꢀ )*ꢀ *,'6(-.Cꢀ 5,''(5.(+Cꢀ Aꢀ P42*.ꢀ )>>2,)58ꢀ 5)-ꢀ L(ꢀ )++2(**(+ꢀ L:ꢀ )>>':4-3ꢀ
X7
g(*4+(*=ꢀS>(-5(2ꢀ(.ꢀ)'Cꢀ ꢀ)'*,ꢀ+(1,-*.2).(+ꢀ.8).ꢀ.8(ꢀ8:+2,3(-ꢀ *41>'4P45).4,-*ꢀ)-+ꢀ0*4-3ꢀ$#Aꢀ+).)L)*(*Cꢀ"-ꢀ.84*ꢀ5)*(=ꢀZ(ꢀ>2(*(-.ꢀ
2)-*P(2ꢀ,5502*ꢀ64)ꢀ.Z,ꢀ>)'')+401M+4P,21).(ꢀ*>(54(*ꢀP2,1ꢀ.Z,ꢀ )ꢀ*41>'4P4(+ꢀ5,1>)2).46(ꢀ)**(**1(-.ꢀ,Pꢀ.8(ꢀ>2,+05.4,-ꢀ,PꢀBꢀe3ꢀ
4PP(2(-.ꢀTA5ꢀ1,'(50'(*ꢁꢀ.8(ꢀ.Z,ꢀP,21:'ꢀ8:+2,3(-*ꢀP2,1ꢀ.8(ꢀ ,PꢀSA5ꢀL:ꢀ5,-6(-.4,-)'ꢀ8:+2,3(-).4,-ꢀ)-+ꢀ5).)':.45ꢀ.2)-*P(2ꢀ
Z,ꢀ+4P,21).(ꢀ*>(54(*ꢀ5,-5(2.(+':ꢀ8:+2,3(-).(ꢀ.8(ꢀ+,0L'(ꢀ 8:+2,3(-).4,-ꢀ0*4-3ꢀTA5ꢀ)*ꢀ)ꢀ2(+05.4,-ꢀ)3(-.=ꢀ2(*>(5.46(':Cꢀ
.
+
.
L,-+Cꢀ!8(ꢀ)54+ꢀ>2,.,-ꢀZ)*ꢀ-,.ꢀ4-6,'6(+ꢀ4-ꢀ.8(ꢀ8:+2,3(-).4,-Cꢀ T4302(ꢀS?Mbꢀ*8,Z*ꢀ.8(ꢀL,0-+)24(*ꢀ,Pꢀ.8(ꢀ(6)'0).(+ꢀ*:*.(1*Cꢀ"-ꢀ
S>(-5(2ꢀ).ꢀ)'Cꢀ5,-+05.(+ꢀ.8(42ꢀ(<>(241(-.*ꢀZ4.8ꢀ)ꢀTA5FGA5ꢀ1,'ꢀ ,02ꢀ)>>2,<41).4,-=ꢀ.8(*(ꢀ(<5'0*46(':ꢀ4-5'0+(ꢀ.8(ꢀ>2,+05.4,-ꢀ,Pꢀ
2
).4,ꢀ,PꢀB7Cꢀ&+M+4P,21).(ꢀ*>(54(*ꢀ5)--,.ꢀL(ꢀ4-6,'6(+ꢀ4-ꢀ,02ꢀ5)*(=ꢀ .8(ꢀ2(+05.4,-ꢀ)3(-.*ꢀQU ꢀ,2ꢀTA5Rꢀ)-+ꢀ.8(42ꢀ5,-+4.4,-4-3ꢀ.,ꢀ2()58ꢀ
;
,
8
,
.8(2Z4*(ꢀ.8(ꢀ:4('+ꢀ,PꢀSA5ꢀZ,0'+ꢀ8)6(ꢀL((-ꢀ1)<4101ꢀ[7ꢀ^ꢁꢀZ(ꢀ .8(ꢀ 2()5.4,-ꢀ >2(**02(Cꢀ W(ꢀ )**01(ꢀ .8).ꢀ L,.8ꢀ 8)6(ꢀ L((-ꢀ
)6(ꢀ0*(+ꢀ)ꢀ*.,4584,1(.245ꢀTA5FGA5ꢀ2).4,ꢀ)-+ꢀ5,-*(O0(-.':ꢀ ,L.)4-(+ꢀ P2,1ꢀ P,**4'ꢀ P((+*.,5e*Cꢀ !84*ꢀ )>>2,)58ꢀ 4*ꢀ -((+(+ꢀ
-':ꢀ,-(ꢀP,2145ꢀ1,'(50'(ꢀ5)-ꢀL(ꢀ4-6,'6(+ꢀ4-ꢀ.8(ꢀ8:+2,3(-).4,-Cꢀ L(5)0*(ꢀ,Pꢀ.8(ꢀ32().ꢀ+4PP(2(-5(*ꢀ2(O042(+ꢀ.,ꢀ+246(ꢀL,.8ꢀ.:>(*ꢀ,Pꢀ
"
-ꢀ,02ꢀ5)*(ꢀ.8(ꢀ*(5,-+ꢀ8:+2,3(-ꢀ.,ꢀ8:+2,3(-).(ꢀ.8(ꢀ+,0L'(ꢀ 2(+05.4,-*=ꢀ1)4-':ꢀP,50*(+ꢀ,-ꢀ.8(ꢀ>2(**02(ꢀ5,-+4.4,-*=ꢀO04.(ꢀ
L,-+ꢀ4*ꢀ-,.ꢀ)ꢀP,21:'ꢀUꢀP2,1ꢀ)ꢀ*(5,-+ꢀTACꢀ".ꢀ10*.ꢀ5,1(ꢀP2,1ꢀ 8438ꢀ4-ꢀ.8(ꢀ5)*(ꢀ,Pꢀ5,-6(-.4,-)'ꢀ8:+2,3(-).4,-CꢀA**01>.4,-*ꢀ
-,.8(2ꢀ*,025(C P,2ꢀ+).)ꢀ5,''(5.4,-ꢀ)-+ꢀP,2ꢀ$#Aꢀ5)'50').4,-*ꢀ1(.8,+,',3:ꢀ8)6(ꢀ
)
AꢀP42*.ꢀ>,**4L4'4.:ꢀ4*ꢀ.8(ꢀ)54+ꢀ>2,.,-*CꢀU,Z(6(2=ꢀ.8(ꢀ2(*0'.*ꢀ,PꢀT43Cꢀ L((-ꢀ+(.)4'(+ꢀ4-ꢀ.8(ꢀ*0>>'(1(-.)2:ꢀ+).)Cꢀ
Xꢀ+(*524L4-3ꢀ.8(ꢀ(PP(5.ꢀ,Pꢀ-(0.2)'4*4-3ꢀ.8(ꢀ>2,.,-*ꢀ,PꢀTA5ꢀ)-+ꢀ T4302(ꢀaꢀ*8,Z*ꢀ.8(ꢀ2(').46(ꢀ5,-.24L0.4,-ꢀ,Pꢀ.8(ꢀ(6)'0).(+ꢀ
GA5ꢀ*8,Z(+ꢀ.8).ꢀ.8(ꢀ8:+2,3(-).4,-ꢀ4*ꢀ6(2:ꢀP)*.ꢀ,-5(ꢀ)''ꢀ.8(ꢀ *:*.(1*ꢀ.,ꢀ.8(ꢀ+4PP(2(-.ꢀ(-642,-1(-.)'ꢀ41>)5.*ꢀ5).(3,24(*Cꢀ!8(ꢀ
>
#
,
,
2,.,-*ꢀ ,Pꢀ P,2145ꢀ )54+ꢀ )-+ꢀ 1)'(45ꢀ )54+ꢀ )2(ꢀ -(0.2)'4I(+Cꢀ 5).)':.45ꢀ8:+2,3(-ꢀ.2)-*P(2ꢀ>).8Z):ꢀ0*4-3ꢀTA5ꢀ)*ꢀ8:+2,3(-ꢀ
,-*(O0(-.':=ꢀ4-ꢀQ5',*(ꢀ.,Rꢀ-(0.2)'ꢀ5,-+4.4,-*ꢀ.8(ꢀ>)2.454>).4,-ꢀ +,-,2ꢀ '()+*ꢀ .,ꢀ ',Z(2ꢀ 41>)5.*=ꢀ 5,1>)2(+ꢀ .,ꢀ 5,-6(-.4,-)'ꢀ
z
PꢀU ꢀ4-ꢀ.8(ꢀ8:+2,3(-).4,-ꢀ5)-ꢀL(ꢀ20'(+ꢀ,0.Cꢀ!84*ꢀ'(P.ꢀU
;
@ꢀ)*ꢀ.8(ꢀ 8:+2,3(-).4,-=ꢀ 4-ꢀ 5).(3,24(*ꢀ *058ꢀ )*ꢀ 5'41).(ꢀ 58)-3(ꢀ Q##R=ꢀ
z
-':ꢀ>,**4L'(ꢀ*,025(ꢀ8:+2,3(-Cꢀ!8(ꢀ>2(*(-5(ꢀ,PꢀU ꢀ4-ꢀ.8(ꢀ 801)-ꢀ.,<454.:ꢀQU!R=ꢀZ).(2ꢀ0*(ꢀ)-+ꢀ5010').46(ꢀ(-(23:ꢀ+(1)-+ꢀ
(+401ꢀQ>)2.4)'ꢀ,2ꢀ-,ꢀ-(0.2)'4*).4,-ꢀ,Pꢀ.8(ꢀ)54+*Rꢀ5'()2':ꢀ*',Z(+ꢀ Q#%?RCꢀ?4PP(2(-5(*ꢀ4-ꢀ+).)ꢀ5,22(*>,-+4-3ꢀ.,ꢀ5'41).(ꢀ58)-3(ꢀQ##Rꢀ
,Z-ꢀ.8(ꢀ2()5.4,-ꢀ2).(ꢀ.8).ꢀ1()-*ꢀ.8).ꢀ4Pꢀ>2,.,-*ꢀ)2(ꢀ4-6,'6(+ꢀ )-+ꢀ5010').46(ꢀ(-(23:ꢀ+(1)-+ꢀQ#%?Rꢀ)2(ꢀ(*>(54)'':ꢀ2(1)2e)L'(ꢀ
-ꢀ.8(ꢀ8:+2,3(-).4,-=ꢀ.8(:ꢀ2(*0'.ꢀ4-ꢀ)-ꢀ4-84L4.4,-ꢀ,Pꢀ.8(ꢀP)*.(2ꢀ 4-+45).4-3ꢀ.8).ꢀ#!Uꢀ4-6,'6(*ꢀ)ꢀ*)64-3ꢀ,Pꢀ)2,0-+ꢀ[7ꢀ^ꢀ,Pꢀ.8(ꢀ
1
+
4
1
1
(58)-4*1ꢀ4-6,'64-3ꢀU
;
@CꢀQS58(1(ꢀS?MBꢀ*011)24I(+ꢀ.8(ꢀ#!Uꢀ (-642,-1(-.)'ꢀ41>)5.*ꢀ5)0*(+ꢀL:ꢀ5,-6(-.4,-)'ꢀ8:+2,3(-).4,-Cꢀ
(58)-4*1ꢀ >2,>,*(+RCꢀ A5.0)'':=ꢀ Z8(-ꢀ Z(ꢀ 5,-+05.(+ꢀ .8(ꢀ !84*ꢀP)5.ꢀ4*ꢀ1)4-':ꢀ2(').(+ꢀ.,ꢀ.Z,ꢀP)5.,2*CꢀT42*.=ꢀ.8(ꢀ>2,+05.4,-ꢀ
2
()5.4,-ꢀZ4.8ꢀ)>2,.45ꢀ*,'6(-.*ꢀQ?GS@ꢀ,2ꢀ)5(.,-4.24'(Rꢀ0-+(2ꢀ.8(ꢀ ,Pꢀ8:+2,3(-ꢀL:ꢀ*.()1ꢀ2(P,214-3ꢀ,Pꢀ-).02)'ꢀ3)*ꢀQ.8(ꢀ1,*.ꢀ
,-+4.4,-*ꢀ,PꢀT43CꢀB=ꢀ.8(ꢀSA5ꢀ:4('+ꢀ)P.(2ꢀBꢀ8ꢀ,Pꢀ2()5.4,-ꢀZ)*ꢀ 5,11,-ꢀ 4-+0*.24)'ꢀ >2,5(**Rꢀ 41>'4(*ꢀ ')23(ꢀ 5)2L,-ꢀ +4,<4+(ꢀ
(3'434L'(ꢀQL(',Zꢀ;ꢀ^=ꢀ.8(ꢀ2(*0'.*ꢀ)2(ꢀ-,.ꢀ.)L0').(+R=ꢀZ8(2()*ꢀ4-ꢀ (14**4,-*ꢀ>(2ꢀe3ꢀ,PꢀU;XDC
,-.2)*.ꢀ)ꢀSA5ꢀ:4('+ꢀ,Pꢀ[7ꢀ^ꢀ4*ꢀ,L.)4-(+ꢀ4-ꢀZ).(2ꢀQ*((ꢀT43ꢀBRCꢀ!84*ꢀ
P)5.ꢀ346(*ꢀ)++4.4,-)'ꢀ*0>>,2.ꢀ.,ꢀ.8(ꢀ8:>,.8(*4*ꢀ.8).ꢀZ).(2ꢀ4*ꢀ
5
-
5
+
42(5.':ꢀ4-6,'6(+ꢀ4-ꢀ.8(ꢀ+,-).4,-ꢀ,Pꢀ.8(ꢀ*(5,-+ꢀUꢀ-((+(+ꢀP,2ꢀ.8(ꢀ
z
8:+2,3(-).4,-ꢀ)-+ꢀ.8).ꢀ.8(ꢀ>2(*(-5(ꢀ,PꢀU ꢀ4*ꢀ)5.0)'':ꢀ4-84L4.4-3ꢀ
.
8(ꢀ2()5.4,-CꢀW4.84-ꢀ.84*ꢀ5,-.(<.=ꢀ6(2:ꢀ2(5(-.':ꢀ.8(ꢀ41>,2.)-.ꢀ
,'(ꢀ)-+ꢀ.8(ꢀ+42(5.ꢀ>)2.454>).4,-ꢀ,Pꢀ.8(ꢀU @ꢀ4-ꢀ.8(ꢀ1(58)-4*1ꢀ,Pꢀ
2
;
!
84*ꢀ/,02-)'ꢀ4*ꢀoꢀ!8(ꢀ ,:)'ꢀS,54(.:ꢀ,Pꢀ#8(14*.2:ꢀ;7<<
HVꢀX 60C=ꢀ;7BD=ꢀꢁꢁ=ꢀBMDꢀnꢀSS
&
'()*(ꢀ+,ꢀ-,.ꢀ)+/0*.ꢀ1)234-*

&
'()*( Gꢀ +r ,e ꢀe- n, C. ꢀ h) +e /m0 *i s. tꢀ 1r y)234-*
Page 12 of 14
View Article Online
DOI: 10.1039/C9GC04221K
A:;9 <=
>.2'(!#ꢀ?!0+
ꢀ
*8,Z-=ꢀ.8(ꢀ0*(ꢀ,Pꢀ('(5.2454.:ꢀ4*ꢀ.8(ꢀe(:ꢀ5,-.24L0.,2ꢀ.,ꢀ801)-ꢀ
,<454.:ꢀQU!Rꢀ)-+ꢀP2(*8Z).(2ꢀ(0.2,>845).4,-ꢀQT%Rꢀ5).(3,24(*ꢀ)-+ꢀ
.ꢀ4*ꢀ2(*>,-*4L'(ꢀP,2ꢀ8)'Pꢀ,Pꢀ,.8(2ꢀ(-642,-1(-.)'ꢀ4-+45).,2*=ꢀ*058ꢀ
.
4
)
*ꢀ.(22(*.24)'ꢀ)54+4P45).4,-ꢀQ!ARꢀ)-+ꢀL'0(ꢀZ).(2ꢀ5,-*01>.4,-C
3)2+4-3ꢀ .(22(*.24)'ꢀ )54+4P45).4,-ꢀ Q!ARꢀ )-+ꢀ P2(*8Z).(2ꢀ
0.2,>845).4,-ꢀ QT%R=ꢀ .8(*(ꢀ )2(ꢀ .8(ꢀ Z()e(*.ꢀ (-642,-1(-.)'ꢀ
,4-.*ꢀ)**,54).(+ꢀ.,ꢀ.8(ꢀ0*(ꢀ,PꢀTA5ꢀ)*ꢀ8:+2,3(-ꢀ+,-,2Cꢀ!84*ꢀ4*ꢀ
*524L(+ꢀ.,ꢀ.8(ꢀ>2,+05.4,-ꢀ,PꢀTA5ꢀP2,1ꢀ1(.8:'ꢀP,21).(=ꢀ)ꢀ
(
(
>
)
>2,5(**ꢀ.8).ꢀ4-6,'6(*ꢀ8438(2ꢀ(14**4,-*ꢀ,Pꢀ-4.2,3(-ꢀ,<4+(*ꢀ)-+ꢀ
>8,*>8).(*ꢀ.8)-ꢀ.8,*(ꢀ5,22(*>,-+4-3ꢀ.,ꢀ.8(ꢀ*.()1ꢀ2(P,214-3ꢀ
>2,5(**ꢀP,2ꢀ8:+2,3(-ꢀ1)-0P)5.02(C
?
(*>4.(ꢀ .8(ꢀ *41>'4P4(+ꢀ )**(**1(-.ꢀ ,Pꢀ .8(ꢀ (-642,-1(-.)'ꢀ
(2P,21)-5(ꢀ,Pꢀ.8(ꢀSA5ꢀ>2,+05.4,-ꢀL:ꢀP,2145ꢀ)54+ꢀ#!U=ꢀ.8(ꢀ
(*0'.*ꢀ1)e(ꢀ(64+(-.ꢀ.8(ꢀ(-642,-1(-.)'ꢀL(-(P4.*ꢀ)**,54).(+ꢀ
Z4.8ꢀ .84*ꢀ .(58-,',3:ꢀ )*ꢀ 5,1>)2(+ꢀ .,ꢀ 5,-6(-.4,-)'ꢀ
:+2,3(-).4,-ꢀ,PꢀGA5Cꢀ$#Aꢀ4-+45).(*ꢀ)ꢀ5'()2ꢀ2(+05.4,-ꢀ4-ꢀ.8(ꢀ
1>)5.*ꢀ )**,54).(+ꢀ .,ꢀ 5'41).(ꢀ 58)-3(ꢀ )-+ꢀ -,-M2(-(Z)L'(ꢀ
(*,025(*ꢀ+(>'(.4,-ꢀL:ꢀ0*4-3ꢀ.84*ꢀ-(Zꢀ)>>2,)58C
5(-.':=ꢀ$#Aꢀ,Pꢀ.8(ꢀ>2,+05.4,-ꢀ,PꢀL4,1)**M+(246(+ꢀTA5ꢀ8)*ꢀ
L((-ꢀ 5,-+05.(+ꢀ 4-ꢀ 5,1>)24*,-ꢀ Z4.8ꢀ .8(ꢀ 5,-6(-.4,-)'ꢀ
>
2
8
4
M%/2'+ꢀ T8ꢀ (').46(ꢀ 5,-.24L0.4,-ꢀ .,ꢀ +4PP(2(-.ꢀ (-642,-1(-.)'ꢀ
2
41>)5.ꢀ5).(3,24(*ꢀ,PꢀTA5ꢀ>2,+05.4,-ꢀP2,1ꢀGA5ꢀL:ꢀ5,-6(-.4,-)'ꢀ
(
8:+2,3(-).4,-ꢀQL'0(ꢀL)2*Rꢀ)-+ꢀ5).)':.45ꢀ8:+2,3(-ꢀ.2)-*P(2ꢀP2,1ꢀ
TA5ꢀQ32((-ꢀL)2*RCꢀ##ꢁꢀ#'41).(ꢀ58)-3(fꢀ ?ꢁꢀ (*,025(ꢀ+(>'(.4,-=ꢀ
TWꢁꢀT2(*8ꢀZ).(2ꢀ+(1)-+fꢀU!ꢁꢀ!,.)'ꢀ801)-ꢀ.,<454.:fꢀ&@Tꢁꢀ
Xi
>
(.2,58(145)'ꢀ 2,0.( Cꢀ !84*ꢀ )-)':*4*ꢀ 8)*ꢀ *8,Z(+ꢀ .8).=ꢀ
(>(-+4-3ꢀ,-ꢀ.8(ꢀ.:>(ꢀ,PꢀL4,1)**=ꢀ2(-(Z)L'(ꢀTA5ꢀ1):ꢀ>2(*(-.ꢀ
+
&
8,.,58(145)'ꢀ ,I,-(ꢀ P,21).4,-fꢀ #%?ꢁꢀ #010').46(ꢀ (-(23:ꢀ
(1)-+C
P02.8(2ꢀ41>2,6(1(-.*ꢀ4-ꢀ*,1(ꢀ,Pꢀ.8(ꢀ(-642,-1(-.)'ꢀ41>)5.ꢀ
).(3,24(*ꢀ'4e(ꢀ##=ꢀU!ꢀ)-+ꢀZ).(2ꢀ0*(ꢀQ*((ꢀS?ꢀ*(5.4,-ꢀP,2ꢀ)ꢀ1,2(ꢀ
(.)4'(+ꢀ+4*50**4,-RCꢀ#,-*(O0(-.':=ꢀ.8(*(ꢀ41>2,6(1(-.*ꢀZ4''ꢀ
L(-(P4.ꢀ'4e(Z4*(ꢀ.8(ꢀ#!Uꢀ,PꢀGA5ꢀ.,ꢀSA5ꢀ.8).ꢀ0*(*ꢀL4,1)**ꢀ
+
5
+
Aꢀ*43-4P45)-.ꢀ>)2.ꢀ,Pꢀ.84*ꢀ4*ꢀ4-8(2(-.ꢀ.,ꢀ.8(ꢀ>2,5(**ꢀ*4-5(ꢀ#@
,M>2,+05.ꢀ,Pꢀ.8(ꢀ2()5.4,-ꢀ*58(1(ꢀQ#U ꢀzꢀ;ꢀU @ꢀ{ꢀ#@ ꢀzꢀXꢀU
80*=ꢀ/0*.ꢀ.8(ꢀ*.,4584,1(.2:ꢀ4-ꢀ.8(ꢀ>2,+05.4,-ꢀ,Pꢀ8:+2,3(-ꢀ
;
ꢀ4*ꢀ)ꢀ
5
X
;
;
;
RCꢀ
+(246(+ꢀTA5C
!
ꢀꢀ
4-6,'6(*ꢀ)ꢀ+42(5.ꢀ(14**4,-ꢀ,Pꢀ[C[ꢀe3ꢀ,Pꢀ#@
;
ꢀ>(2ꢀe3ꢀ,PꢀU
;
CꢀA++4-3ꢀ
.
(&#2)%.()
.
8(ꢀ2(*.ꢀ,Pꢀ.8(ꢀ2(O042(+ꢀ*.(>*ꢀ4-52()*(*ꢀ.8(ꢀ#@ ꢀ(14**4,-*ꢀ.,ꢀ
;
XD=XX
M(Oꢀ>(2ꢀe3ꢀ,PꢀU
;
A1,-3ꢀ.8(ꢀ+4PP(2(-.ꢀ-,L'(ꢀ1(.)'ꢀ)-+ꢀ*0>>,2.ꢀ*.0+4(+=ꢀ&+F#ꢀ4*ꢀ
1
,2(ꢀ.8)-ꢀB7ꢀe3ꢀ#@
;
C
ꢀ@-ꢀ.8(ꢀ,.8(2ꢀ8)-+=ꢀ.8(ꢀ
.
8(ꢀ1,*.ꢀ(PP454(-.ꢀ)-+ꢀ2,L0*.ꢀ5).)':*.ꢀP,2ꢀ.8(ꢀ5).)':.45ꢀ.2)-*P(2ꢀ
>2,+05.4,-ꢀ,PꢀBꢀe3ꢀ,PꢀTA5ꢀL:ꢀ.8(ꢀ1(.8:'ꢀP,21).(ꢀ2,0.(ꢀQ.8(ꢀ1,*.ꢀ
X[
8:+2,3(-).4,-ꢀ,Pꢀ1)'(45ꢀ)54+ꢀ.,ꢀ*0554-45ꢀ)54+ꢀ0*4-3ꢀP,2145ꢀ)54+ꢀ
0
*0)'ꢀ,-(Rꢀ'()+*ꢀ.,ꢀDꢀe3ꢀ#@
-,21,0*ꢀ +4PP(2(-5(ꢀ 5,1>)2(+ꢀ .,ꢀ 8:+2,3(-ꢀ >2,+05.4,-M
(').(+ꢀ (14**4,-*Cꢀ ?(*>4.(ꢀ TA5ꢀ 5,-*01>.4,-ꢀ +024-3ꢀ GA5ꢀ
;
M(Oꢀ>(2ꢀe3ꢀ,PꢀTA5 =ꢀZ8458ꢀ4*ꢀ)-ꢀ
)
*ꢀU
(+401ꢀ)-+ꢀZ4.8ꢀ)ꢀ*.,4584,1(.245ꢀ)1,0-.ꢀ,PꢀP,2145ꢀ)54+C
-ꢀ)ꢀP4<(+ꢀL(+ꢀ2()5.,2ꢀ)-+ꢀ0-+(2ꢀ)ꢀ5,-.4-0,0*ꢀP',Zꢀ,PꢀGA5MTA5ꢀ
,'0.4,-*ꢀ-,ꢀ*43-ꢀ,Pꢀ+()5.46).4,-ꢀZ)*ꢀ,L*(26(+ꢀ(4.8(2ꢀ0*4-3ꢀ
;
ꢀ*,025(Cꢀ"-.(2(*.4-3':ꢀ.8(ꢀ2()5.4,-ꢀZ)*ꢀ5,-+05.(+ꢀ4-ꢀZ).(2ꢀ
(
1
2
2
"
(+05.4,-ꢀ)'*,ꢀ'()+*ꢀ.,ꢀ)ꢀ+42(5.ꢀ(14**4,-ꢀ,Pꢀ#@
;
ꢀQ7CDaꢀe3ꢀ,Pꢀ
*
;
#@ Fe3ꢀ SA5R=ꢀ .84*ꢀ O0)-.4.:ꢀ 4*ꢀ 1058ꢀ ',Z(2ꢀ .8)-ꢀ .8(ꢀ
-
(0.2)'4I(+ꢀ Q0>ꢀ .>ꢀ B7ꢀ Z.C^ꢀ ,Pꢀ (O046)'(-.ꢀ GA5Rꢀ ,2ꢀ -,-M
(0.2)'4I(+ꢀ1)'(45ꢀ)-+ꢀP,2145ꢀ)54+*ꢀQ0>ꢀ.,ꢀB[ꢀZ.C^ꢀ,PꢀGA5RCꢀ"-ꢀ
*.,4584,1(.245)'':ꢀ(14..(+ꢀL:ꢀ.8(ꢀ>2,+05.4,-ꢀ,Pꢀ.8(ꢀ2(O042(+ꢀ
-
8
[
+
:+2,3(-ꢀ.,ꢀ>2,+05(ꢀ)-ꢀ(O046)'(-.ꢀ)1,0-.ꢀ,PꢀSA5ꢁꢀ
C[ꢀe3ꢀ,Pꢀ#@ Fe3ꢀU;ꢀ<ꢀ7C;[Xꢀe3ꢀU ꢀ5,-*01(+ꢀQ*((ꢀ*0>>'(1(-.)2:ꢀ
).)Rꢀ`ꢀBCXꢀe3ꢀ,Pꢀ+42(5.ꢀ(14**4,-ꢀ,Pꢀ#@
.
8(ꢀ5)*(ꢀ,Pꢀ)54+ꢀ*,'0.4,-*=ꢀ.8(ꢀ5).)':*.ꢀZ)*ꢀZ,2e4-3ꢀP,2ꢀ5)CꢀbD7ꢀ
;
;
8C
;
C
MB MB
Aꢀ*>)5(ꢀ.41(ꢀ:4('+ꢀQS!wRꢀ,Pꢀ)L,6(ꢀBC;bꢀ3ꢀSA5c35). c8 ꢀZ)*ꢀ
;
A*ꢀP,2ꢀ.8(ꢀ#%?ꢀ5).(3,2:=ꢀ0*4-3ꢀTA5ꢀ4-*.()+ꢀ,PꢀU ꢀ*)6(*ꢀ>241)2:ꢀ
)
584(6(+ꢀZ4.8ꢀ+4*,+401ꢀ1)'().(ꢀ)-+ꢀ*,+401ꢀP,21).(ꢀ*,'0.4,-*ꢀ
(
-(23:ꢀ 5,-*01>.4,-Cꢀ !84*ꢀ 4*ꢀ 1)4-':ꢀ +0(ꢀ .,ꢀ .8(ꢀ +4PP(2(-.ꢀ
Z,2e4-3ꢀZ4.8ꢀ)ꢀB7ꢀZ.C^ꢀ,Pꢀ(O046)'(-.ꢀGA5=ꢀ).ꢀB[7ꢀ\#=ꢀB7ꢀL)2ꢀ,Pꢀ
MB
>2,5(**(*ꢀ)-+ꢀ2)Zꢀ1).(24)'*ꢀ0*(+ꢀP,2ꢀ.8(ꢀ1)-0P)5.02(ꢀ,PꢀL,.8ꢀ
Y
;
ꢀ)-+ꢀ)ꢀWUS_ꢀ`ꢀB;ꢀ8 ꢀQ5,-.)5.ꢀ.41(ꢀ`ꢀ[ꢀ14-RCꢀ"-ꢀ.8(ꢀ5)*(ꢀ,Pꢀ
2
(+054-3ꢀ)3(-.CꢀW8(2()*ꢀ.8(ꢀ1(.8:'ꢀP,21).(ꢀ2,0.(=ꢀL)*(+ꢀ,-ꢀ
0
*4-3ꢀB[ꢀZ.C^ꢀ,Pꢀ-,-M-(0.2)'4I(+ꢀGA5=ꢀ.8(ꢀS!wꢀZ)*ꢀBCabꢀ3ꢀ
MB MB
1
(.8)-,'ꢀ5)2L,-:').4,-=ꢀ5,-*01(*ꢀ)ꢀ>241)2:ꢀ(-(23:ꢀ+(1)-+ꢀ
SA5c35). c8 CꢀAꢀ.,.)'ꢀ,PꢀE[7ꢀ3ꢀSA5c35).MBꢀZ(2(ꢀ>2,+05(+ꢀ+024-3ꢀ.8(ꢀ
,PꢀbDꢀG9Fs3ꢀTA5=ꢀ*.()1ꢀ2(P,214-3ꢀ,Pꢀ-).02)'ꢀ3)*ꢀ2(O042(*ꢀ;7Eꢀ
'
,-3M.(21ꢀ (<>(241(-.*ꢀ Z4.8ꢀ -,-M-(0.2)'4*(+ꢀ GA5MTA5ꢀ
<>(241(-.*=ꢀ.8).ꢀ4-ꢀ.(21*ꢀ,Pꢀ&+ꢀ2(>2(*(-.*ꢀ1,2(ꢀ.8)-ꢀBE777ꢀ3ꢀ
SA5c3&+MBC
8(ꢀ 2()5.4,-ꢀ 2()'':ꢀ >2,5((+*ꢀ 64)ꢀ 5).)':.45ꢀ .2)-*P(2ꢀ
:+2,3(-).4,-ꢀ4-ꢀZ8458ꢀP,21:'ꢀUꢀ,PꢀP,2145ꢀ)54+ꢀ>2,64+(*ꢀ,-(ꢀ,Pꢀ
8(ꢀUꢀ-((+(+ꢀP,2ꢀ.8(ꢀ8:+2,3(-).4,-Cꢀ"-ꢀ5',*(ꢀ.,ꢀ-(0.2)'ꢀ>Uꢀ
,-+4.4,-*ꢀ.8(ꢀ2()5.4,-ꢀ4*ꢀP)*.(2ꢀ.8)-ꢀ4-ꢀ)54+45ꢀ>Uꢀ)-+ꢀZ).(2ꢀ
0>>'4(*ꢀ.8(ꢀ*(5,-+ꢀUꢀ-((+(+ꢀP,2ꢀ.8(ꢀ2()5.4,-Cꢀ"-ꢀ)54+45ꢀ>Uꢀ.8(ꢀ
-6,'6(1(-.ꢀ,Pꢀ)54+ꢀ>2,.,-*ꢀ5)--,.ꢀL(ꢀ20'(+ꢀ,0.ꢀZ4.8ꢀ.8(ꢀ+).)ꢀ
,ꢀP)2ꢀ)6)4')L'(=ꢀL0.ꢀ.8(ꢀ>2(*(-5(ꢀ,Pꢀ>2,.,-*ꢀ*',Z*ꢀ+,Z-ꢀ.8(ꢀ
()5.4,-ꢀ2).(C
G9ꢀ,Pꢀ>241)2:ꢀ(-(23:ꢀ>(2ꢀs3ꢀ,PꢀU
,ꢀ.8(ꢀ5,-*01>.4,-ꢀ,Pꢀ.84*ꢀP,**4'ꢀP0('ꢀ)*ꢀL,.8=ꢀ2()5.)-.ꢀ)-+ꢀ
().4-3ꢀ)3(-.C
-ꢀ.8(ꢀ5)*(ꢀ,Pꢀ801)-ꢀ.,<454.:ꢀQU!R=ꢀ4.ꢀ4*ꢀ2(1)2e)L'(ꢀ.8).ꢀ.8(ꢀ
;
=ꢀ)'1,*.ꢀ(<5'0*46(':ꢀ)**,54).(+ꢀ
(
.
8
!
"
8
41>)5.ꢀ>2,+05(+ꢀL:ꢀ.8(ꢀ5,-6(-.4,-)'ꢀ8:+2,3(-).4,-ꢀ4*ꢀ-,.ꢀ+0(ꢀ
.
.
,ꢀ.8(ꢀ>2,+05.4,-ꢀ,Pꢀ8:+2,3(-=ꢀL0.ꢀ1)4-':ꢀ.,ꢀ.8(ꢀ5,-*01>.4,-ꢀ
5
,
8
Pꢀ ('(5.2454.:ꢀ 2(O042(+ꢀ P,2ꢀ 3)*ꢀ 5,1>2(**4,-ꢀ 0>ꢀ .,ꢀ .8(ꢀ
*
:+2,3(-).4,-ꢀ >2(**02(ꢀ QXC7ꢀ G&)RCꢀ !)L'(ꢀ S?MXꢀ *8,Z*ꢀ .8(ꢀ
4
2
(').46(ꢀ5,-.24L0.4,-ꢀ,Pꢀ.8(ꢀ8:+2,3(-ꢀ1)-0P)5.02(ꢀ)-+ꢀ3)*ꢀ
*
5
,1>2(**4,-ꢀ*.(>*ꢀ.,ꢀ()58ꢀ(-642,-1(-.)'ꢀ41>)5.ꢀ5).(3,2:CꢀA*ꢀ
2
S@ꢀnꢀHVꢀX 60C=ꢀ;7B;=ꢀꢁꢁ=ꢀBMD
!84*ꢀ/,02-)'ꢀ4*ꢀoꢀ!8(ꢀ ,:)'ꢀS,54(.:ꢀ,Pꢀ#8(14*.2:ꢀ;7<<
&
'()*(ꢀ+,ꢀ-,.ꢀ)+/0*.ꢀ1)234-*

Page 13 of 14
&'()*( Gꢀ +r ,e ꢀe- n, C. ꢀ h) +e /m0 *i s. tꢀ 1r y)234-*
View Article Online
DOI: 10.1039/C9GC04221K
>.2'(!#ꢀ?!0+
ꢀA:;9 <=
Aꢀ>2('414-)2:ꢀ(-642,-1(-.)'ꢀ)**(**1(-.ꢀ4-+45).(*ꢀ.8).ꢀ.8(ꢀ BB
TA5ML)*(+ꢀ#!Uꢀ.(58-,',3:ꢀ2(*0'.*ꢀ4-ꢀ)ꢀ*43-4P45)-.ꢀ2(+05.4,-*ꢀ,Pꢀ
('(6)-.ꢀ(-642,-1(-.)'ꢀ4-+45).,2*ꢀQ*058ꢀ)*ꢀ5'41).(ꢀ58)-3(ꢀ)-+ꢀ
WCꢀV80=ꢀTCꢀ!),=ꢀSCꢀ#8(-=ꢀGCꢀ$4=ꢀwCꢀw)-3ꢀ)-+ꢀJCꢀ$6=ꢀꢁ4#ꢀ
'*+ ,-Vꢀ4506Vꢀ!-1V=ꢀ;7BE=ꢀV=ꢀ;EipD7[C
#
2
B;
BD
BX
B[
Bi
"CꢀA3422(=ꢀ"CꢀJ)-+)24)*=ꢀ&Cꢀ$CꢀA24)*ꢀ)-+ꢀGCꢀ$H>(IꢀJ2)-)+,*=ꢀ
O,&6 **ꢀ4&-E0%*VꢀO,&%0:,-0%2C
5
5
,-*01>.4,-ꢀ,PꢀP,**4'ꢀ2(*,025(*Rꢀ)*ꢀ5,1>)2(+ꢀ.,ꢀ.8,*(ꢀ,Pꢀ
,-6(-.4,-)'ꢀ8:+2,3(-).4,-ꢀ2,0.(=ꢀ.8).ꢀ5)-ꢀL(ꢀ(6(-ꢀ1,2(ꢀ
P)6,2)L'(ꢀ4PꢀL4,1)**M+(246(+ꢀTA5ꢀ4*ꢀ0*(+ꢀ4-*.()+ꢀ,Pꢀ5,-6(-.4,-)'ꢀ
SCꢀg')5eꢀ)-+ꢀTCꢀ$CꢀG0''(2=ꢀL%1Vꢀ;%&<0**ꢀG0*VꢀK0EV=ꢀ;7B7=ꢀSE=ꢀ
iiBpii[C
>
(.2,58(145)'ꢀTA5Cꢀ
,-P'45.*ꢀ,Pꢀ4-.(2(*.
#
!
8(2(ꢀ)2(ꢀ-,ꢀ5,-P'45.*ꢀ.,ꢀ+(5')2(C
qCꢀw0=ꢀSCꢀg')5eꢀ)-+ꢀUCꢀW(4=ꢀHVꢀ4506Vꢀ!-1VꢀK + =ꢀ;77E=ꢀQE=ꢀ
;
B;Dp;B;[C
A&_(.1#+-/+0+(")
9CꢀA'L(2.ꢀ)-+ꢀ&CꢀW)**(2*58(4+=ꢀ$%00-ꢀ4506V=ꢀ;7B[=ꢀSV=ꢀ
BiXp[BbBC
T4-)-54)'ꢀ *0>>,2.ꢀ P2,1ꢀ .8(ꢀ S>)-4*8ꢀ G4-4*.2:ꢀ ,Pꢀ (*()258=ꢀ
[
"
--,6).4,-ꢀ)-+ꢀ]-46(2*4.:ꢀQG"#"YYRꢀQ>2,/(5.*ꢀ#!q;7B[MiX;;iM
DMBM =ꢀ !";7BaM7EXEBaMgM#XB=ꢀ )-+ꢀ !";7BaM7EXEBaMgM#X;Rꢀ
-+ꢀP2,1ꢀ#S"#ꢀQ4M'4-eB7Xaꢀ>2,/(5.Rꢀ4*ꢀ32).(P0'':ꢀ)5e-,Z'(+3(+CꢀwCꢀ
+(-)*ꢀ4*ꢀ)'*,ꢀ.8)-e(+ꢀP,2ꢀ.8(ꢀ>2(>)2).4,-ꢀ,Pꢀ*,1(ꢀ,Pꢀ.8(ꢀ
).)':*.*ꢀ )-+ꢀ *,1(ꢀ ,Pꢀ .8(ꢀ 1()*02(1(-.*ꢀ ,Pꢀ .8(ꢀ 5).)':.45ꢀ Bb
5.464.:CꢀAC#CAC Cꢀ)'*,ꢀ.8)-e*ꢀ.8(ꢀ]-46(2*4.:ꢀ,Pꢀ!,'(+,ꢀP,2ꢀ8(2ꢀ
.)2.M0>ꢀ>)5e)3(C
#
9CꢀA'L(2.=ꢀ CꢀWÄ'P('=ꢀACꢀgÄ*1)--ꢀ)-+ꢀ&CꢀW)**(2*58(4+=ꢀ
-0%12ꢀ!-E,%&-Vꢀ#<,V=ꢀ;7B;=ꢀQ=ꢀbE[ipbEi;C
)
!
,
5
9Cꢀ (458(2.=ꢀgCꢀg20--(2=ꢀACꢀ9(**=ꢀ&CꢀW)**(2*58(4+ꢀ)-+ꢀ9Cꢀ
A'L(2.=ꢀ!-0%12ꢀ!-E,%&-Vꢀ#<,V=ꢀ;7B[=ꢀT=ꢀ;Ea[p;EE7C
)
*
Ba
SCꢀJCꢀW(..*.(4-=ꢀ?CꢀGCꢀA',-*,=ꢀwCꢀ#8,-3ꢀ)-+ꢀ9CꢀACꢀ?01(*45=ꢀ
!-0%12ꢀ!-E,%&-Vꢀ#<,V=ꢀ;7B;=ꢀQ=ꢀaBEEpa;7DC
:
+*+'+(&+)
BE
JCꢀ&)6)2(''4=ꢀ9Cꢀ_(')*O0(Iꢀ@58,)=ꢀACꢀ#)'+)2(''4=ꢀTCꢀ&0II,=ꢀTCꢀ
#
)6)-4ꢀ)-+ꢀ9Cꢀ$Cꢀ?0L,4*=ꢀ4506#'*4506=ꢀ;7B[=ꢀT=ꢀ;;[7p
B
"Cꢀg(58.8,'+=ꢀsCꢀg2(.I=ꢀSCꢀs)L)*54=ꢀ Cꢀs,>4.Ie:ꢀ)-+ꢀACꢀ
S>24-3(2=ꢀ4506Vꢀ!-1VꢀI0<5-&/V=ꢀ;77a=ꢀBE=ꢀiXbpi[XC
;
;[EC
;
;
;
;
7
B
;
D
ACꢀ#8).I4+414.24,0ꢀ)-+ꢀ9CꢀqCꢀg,-+=ꢀ$%00-ꢀ4506V=ꢀ;7B[=ꢀSV=ꢀ
XDibpXDbiC
;
D
X
#CꢀT01)3)''4=ꢀ4-ꢀ[,%\WL+560%ꢀ!-<2</&(03, ꢀ&:ꢀ4506,< /ꢀ
I0<5-&/&12=ꢀ9,8-ꢀW4'(:ꢀ|ꢀS,-*=ꢀ"-5C=ꢀ;77iC
JCꢀ$6=ꢀ#Cꢀ#8(-=ꢀgCꢀ$0=ꢀ9Cꢀ$4=ꢀwCꢀw)-3=ꢀ#Cꢀ#8(-=ꢀ!Cꢀ?(-3=ꢀwCꢀV80ꢀ
GCꢀg(**,-=ꢀ&CꢀJ)''(I,.ꢀ)-+ꢀ#Cꢀ&4-('=ꢀ4506VꢀG0EV=ꢀ;7BX=ꢀSSE=ꢀ
Ba;bpBab7C
)-+ꢀdCꢀU,0=ꢀG#4ꢀꢁ3EV=ꢀ;7Bi=ꢀR=ꢀB7B;bbpB7B;a;C
9Cꢀ$)-=ꢀ9Cꢀ$4-=ꢀVCꢀ#8(-ꢀ)-+ꢀJCꢀw4-=ꢀꢁ4#ꢀ4 + /V=ꢀ;7B[=ꢀQ=ꢀ;7D[p
7XBC
CꢀG)24*5)'=ꢀ&CꢀG)42('(*M!,22(*=ꢀGCꢀ@/(+)=ꢀ"CꢀS}+)L)ꢀ)-+ꢀGCꢀ
;
$H>(IꢀJ2)-)+,*=ꢀ!-0%12ꢀ!-E,%&-Vꢀ#<,V=ꢀ=ꢀ
?@"ꢁB7CB7DEF5[((7;iiieC
VCꢀ?0=ꢀ9CꢀG)=ꢀTCꢀW)-3=ꢀ9Cꢀ$40ꢀ)-+ꢀ9Cꢀd0=ꢀ$%00-ꢀ4506V=ꢀ;7BB=ꢀ
SB=ꢀ[[Xp[[bC
[
i
9CꢀGCꢀ&4-)I,=ꢀGCꢀ%Cꢀ?,14-(=ꢀ_Cꢀ&)260'(*50ꢀ)-+ꢀTCꢀ&(.20=ꢀ
4
+ /VꢀI&3 2=ꢀ;7B[=ꢀ@BZ=ꢀBbp;XC
;
;
X
[
dCꢀ$4ꢀ)-+ꢀwCꢀV8)-3=ꢀ$%00-ꢀ4506V=ꢀ;7Bi=ꢀST=ꢀiXDpiXbC
CꢀsCꢀS)<(-)=ꢀSCꢀS)2)-=ꢀ9Cꢀ"*)2ꢀ)-+ꢀ Cꢀs)0*84e=ꢀ4-ꢀ4'%%0-+ꢀ
K0E0/&(60-+*ꢀ,-ꢀO,&+0<5-&/&12ꢀ -3ꢀO,&0-1,-00%,-1]ꢀ
_Cꢀ$)*(2-)=ꢀACꢀU(2)*=ꢀYCꢀA',-*,MT)3Å-+(I=ꢀACꢀ#CꢀA'L)M 0L4,=ꢀ
CꢀG)24*5)'=ꢀGCꢀ$CꢀJ2)-)+,*ꢀ)-+ꢀGCꢀG(-34L)2=ꢀ4 + /VꢀI&3 2=ꢀ
;
%&3'<+,&-8ꢀ9*&/ +,&-ꢀ -3ꢀ;'%,:,< +,&-ꢀ&:ꢀ9-3'*+%, /ꢀ;%&3'<+*=ꢀ
;
7BX=ꢀ@BE=ꢀ;a[p;EXC
;
7Bi=ꢀ>>Cꢀi7Bpi;EC
;
;
;
;
i
b
a
E
YCꢀA',-*,MT)3Å-+(I=ꢀ"CꢀA3422(I)L)'M!(''(24)=ꢀ&Cꢀ$CꢀA24)*=ꢀ9Cꢀ$Cꢀ
JCꢀT4(22,=ꢀ CꢀG)24*5)'ꢀ)-+ꢀGCꢀ$CꢀJ2)-)+,*=ꢀG#4ꢀꢁ3EV=ꢀ=ꢀ
b
gCꢀ#Cꢀs'(4-=ꢀ9CꢀTCꢀ$CꢀS4'6)=ꢀ!Cꢀ$Cꢀ90-O0(42)=ꢀSCꢀ#Cꢀ )L(',=ꢀ&Cꢀ_Cꢀ
A220+)=ꢀ9Cꢀ$Cꢀ"(-5I)e=ꢀ&Cꢀ%CꢀG)-.(')..,=ꢀ9CꢀJCꢀ#Cꢀ&2)+('')=ꢀSCꢀ_Cꢀ
?@"ꢁB7CB7DEF5X2)BB[iD(C
9
0-4,2ꢀ)-+ꢀACꢀg,-,14=ꢀO,&:'0/*8ꢀO,&(%&3VꢀO,&%0:,-,-1=ꢀ;7Bb=ꢀ
SS=ꢀB7[BpB7iXC
ACꢀ#CꢀA'L)M 0L4,=ꢀ9Cꢀ$CꢀJCꢀT4(22,=ꢀ$Cꢀ$(H-M (4-)=ꢀ CꢀG)24*5)'=ꢀ9Cꢀ
ACꢀ?01(*45ꢀ)-+ꢀGCꢀ$H>(IꢀJ2)-)+,*=ꢀꢁ((/Vꢀ4 + /VꢀOꢀ!-E,%&-V=ꢀ
a
;7BDꢀg4,#,-S(>!~G)2e(.M>,.(-.4)'MP,2M*('(5.(+M>').P,21M
;
7Bb=ꢀ@ꢁ@=ꢀ;iEp;a7C
5
5
8(145)'*~2(>,2.B=ꢀ8..>ꢁFFZZZCL4,5,-*(>.C(0FZ>M
,-.(-.F0>',)+*Fg4,#,-S(>!~G)2e(.M>,.(-.4)'MP,2M
wCꢀ ,+(-)*=ꢀ9Cꢀ$CꢀJCꢀT4(22,=ꢀ CꢀG)24*5)'=ꢀGCꢀ (.0(2.,ꢀ)-+ꢀGCꢀ
H>(IꢀJ2)-)+,*=ꢀI&(Vꢀ4 + /V=ꢀ=ꢀ?@"ꢁB7CB77bF*BB;XXM7BEM
BBXEM;C
*('(5.(+M>').P,21M58(145)'*~2(>,2.BC>+PC
$
7
E
ACꢀ#)2'*,-=ꢀgCꢀ#,334,=ꢀsCꢀ$)0=ꢀ#CꢀG(25,3'4)-,ꢀ)-+ꢀ9CꢀG4''4*=ꢀ4-ꢀ
4506,< /*ꢀ -3ꢀZ'0/*ꢀ:%&6ꢀO,&WO *03ꢀO',/3,-1ꢀO/&<\*=ꢀ(+CꢀTCꢀ
wCꢀ ,+(-)*=ꢀ CꢀG)24*5)'=ꢀ9Cꢀ$CꢀJCꢀT4(22,=ꢀ?CꢀG)2.N-ꢀA',-*,=ꢀ9Cꢀ
ACꢀ?01(*45ꢀ)-+ꢀGCꢀ$H>(IꢀJ2)-)+,*=ꢀ$%00-ꢀ4506V=ꢀ;7Ba=ꢀ
#)6)-4fꢀSCꢀA'L,-(..4fꢀTCꢀg)*4'(fꢀACꢀJ)-+4-4=ꢀW4'(:M_#Uꢀ
_(2')3=ꢀ;7Bi=ꢀ>>CꢀBbDpBE7C
@
ꢁ=ꢀ;aX[p;a[iC
B7
#CꢀSCꢀ$H>(IMJ)2IH-ꢀ)-+ꢀACꢀ9Cꢀ9CꢀS.2)).8,P=ꢀO,&+0<5-&/Vꢀꢁ3EV=ꢀ
7BX=ꢀB@=ꢀabDpE7XC
D7
SCꢀS84=ꢀUCꢀJ0,ꢀ)-+ꢀJCꢀw4-=ꢀ4 + /Vꢀ4&66'-V=ꢀ;7BB=ꢀS@=ꢀbDBp
bDDC
;
!
84*ꢀ/,02-)'ꢀ4*ꢀoꢀ!8(ꢀ ,:)'ꢀS,54(.:ꢀ,Pꢀ#8(14*.2:ꢀ;7<<
HVꢀX 60C=ꢀ;7BD=ꢀꢁꢁ=ꢀBMDꢀnꢀSB
&
'()*(ꢀ+,ꢀ-,.ꢀ)+/0*.ꢀ1)234-*

&
'()*( Gꢀ +r ,e ꢀe- n, C. ꢀ h) +e /m0 *i s. tꢀ 1r y)234-*
Page 14 of 14
View Article Online
DOI: 10.1039/C9GC04221K
A:;9 <=
>.2'(!#ꢀ?!0+
DB
D;
DD
UCꢀJ0,ꢀ)-+ꢀJCꢀw4-=ꢀHVꢀ;52*Vꢀ4506Vꢀ4=ꢀ;7BB=ꢀSSQ=ꢀBb[Bip
Bb[;;C
9Cꢀ$)-=ꢀVCꢀ#8(-=ꢀ9Cꢀ$4-ꢀ)-+ꢀJCꢀw4-=ꢀ$%00-ꢀ4506V=ꢀ;7BX=ꢀSR=ꢀ
XD[BpXD[aC
wCꢀU0)-3=ꢀ#CꢀW0=ꢀWCꢀw0)-=ꢀwCꢀd4)=ꢀdCꢀ$40=ꢀUCꢀw)-3ꢀ)-+ꢀUCꢀ
W)-3=ꢀHVꢀ45,-0*0ꢀ4506Vꢀ#&<V=ꢀ;7Bb=ꢀRE=ꢀbaipbEXC
DX
D[
GCꢀ9CꢀJ4'e(:ꢀ)-+ꢀgCꢀd0=ꢀꢁ4#ꢀ4 + /V=ꢀ;7Bi=ꢀR=ꢀBX;7pBXDiC
!Cꢀ$40=ꢀwCꢀV(-3=ꢀUCꢀV8)-3=ꢀ!CꢀW(4=ꢀdCꢀW0ꢀ)-+ꢀYCꢀ$4=ꢀ
I0+% 503%&-ꢀQ0++V=ꢀ;7Bi=ꢀQV=ꢀXaX[pXaXEC
Di
JCꢀg(23(2(.ꢀ)-+ꢀ&CꢀJ)''(I,.=ꢀ4-ꢀM -3.&&\ꢀ&:ꢀM0+0%&10-0&'*ꢀ
4
+ /2*,*=ꢀ(+CꢀUCꢀsCꢀ)-+ꢀ9CꢀWCꢀJCꢀ%2.'=ꢀW4'(:M_#Uꢀ_(2')3=ꢀ
;
77a=ꢀ>>CꢀXDEpXibC
Db
Da
DE
qCꢀ$4=ꢀ?CꢀW)-3=ꢀwCꢀW0=ꢀWCꢀ$4=ꢀwCꢀV8)-3=ꢀ9Cꢀd4-3ꢀ)-+ꢀVCꢀS0=ꢀ#0(Vꢀ
'%,:VꢀI0<5-&/V=ꢀ;7B7=ꢀV@=ꢀ;EXpD77C
;
SCꢀ )/)3,>)'ꢀ)-+ꢀACꢀTCꢀS>).,')=ꢀꢁ((/Vꢀ4 + /Vꢀꢁꢀ$0-V=ꢀBEEb=ꢀ
SQ@=ꢀiEpaBC
SCꢀ )/)3,>)'ꢀ)-+ꢀACꢀTCꢀS>).,')=ꢀHVꢀL%1Vꢀ4506V=ꢀBEE[=ꢀRꢁ=ꢀ
BDXbpBD[[C
X7
XB
9Cꢀw0ꢀ)-+ꢀ9CꢀgCꢀS>(-5(2=ꢀ4506Vꢀ4&66'-=ꢀBEEa=ꢀBED[pBEDiC
VCꢀV8),=ꢀ Cꢀg)L)L24e=ꢀWCꢀd0(=ꢀwCꢀ$4=ꢀYCꢀGCꢀg2433*=ꢀ?CM!Cꢀ
Y30:(-=ꢀ]CꢀY30:(-=ꢀSCꢀ&Cꢀ#2,**'(:=ꢀSCꢀW)-3=ꢀgCꢀW)-3ꢀ)-+ꢀ?Cꢀ
%Cꢀ (*)*5,=ꢀX +Vꢀ4 + /V=ꢀ;7BE=ꢀQ=ꢀXDBpXDiC
X;
9CꢀG,2(-,=ꢀ#Cꢀ&)L',*ꢀ)-+ꢀ9CꢀG)203}-=ꢀ4-ꢀ"' -+,+ +,E0ꢀ
0+5&3*ꢀ:&%ꢀZ&&3ꢀ# :0+2ꢀ -3ꢀ"' /,+2ꢀ,-ꢀ+50ꢀ^010+ ./0ꢀ
-3'*+%2=ꢀ(+*CꢀTCꢀ&Ç2(IM ,+2N30(I=ꢀ&CꢀSe)-+)14*ꢀ)-+ꢀ_Cꢀ
)'+2)14+4*=ꢀS>24-3(2ꢀ"-.(2-).4,-)'ꢀ&0L'4*84-3=ꢀ#8)1=ꢀ;7Ba=ꢀ
>Cꢀ;[[p;EDC
>
9
_
>
XD
XX
9Cꢀ?0P,02=ꢀ?Cꢀ&CꢀS(22)-,=ꢀ9Cꢀ$CꢀJ}'6(I=ꢀ9CꢀG,2(-,ꢀ)-+ꢀ#Cꢀ
J)25N)=ꢀ9-+VꢀHVꢀM23%&10-ꢀ!-0%12=ꢀ;77E=ꢀBE=ꢀBDb7pBDbiC
YCꢀVCꢀG02)+,6ꢀ)-+ꢀ!CꢀYCꢀ_(I42,É'0=ꢀ9-+VꢀHVꢀM23%&10-ꢀ!-0%12=ꢀ
;
77[=ꢀBꢁ=ꢀ;;[p;DbC
X[
Xi
9CꢀS0..(2=ꢀ!<&,-E0-+ꢀG0(V=ꢀ;77b=ꢀꢁ=ꢀBpX7;C
UCꢀUCꢀs8,,=ꢀWCꢀ$Cꢀ%(ꢀ)-+ꢀ_Cꢀ"*,-4=ꢀ$%00-ꢀ4506V=ꢀ;7Bi=ꢀST=ꢀ
BEB;pBE;;C
SEꢀnꢀHVꢀX 60C=ꢀ;7B;=ꢀꢁꢁ=ꢀBMD
!84*ꢀ/,02-)'ꢀ4*ꢀoꢀ!8(ꢀ ,:)'ꢀS,54(.:ꢀ,Pꢀ#8(14*.2:ꢀ;7<<
&
'()*(ꢀ+,ꢀ-,.ꢀ)+/0*.ꢀ1)234-*