Gaseous Ions and
Chemical Mass Spectrometry
Diethard K. Böhme
Ion Chemistry Laboratory
Department of Chemistry
Centre for Research in Mass Spectrometry
Centre for Research in Earth & Space Science
York University, Toronto, Canada
CIC Medal Lecture
Winnipeg, 2007
Gaseous Ions
_____________________________________________________
NH2
N
C+,
Fe+,
Si+,
Ionospheric,
Biological
Ions
Ions
Found
in
Atomic
Cations
Carbonaceous
Ions
Cometary
andn+
Solution
+
+
+
+
n+
+3 , C
C
,C
70 +
+6H6K,+ C60 , C
Er+, C2Nb
Rh
Yb
Ions
-, Interstellar
-, C H O
-, +(CH
-+
Co
Cu
OH
CH
O
)
CO
+
+
3 Fe 2coronene
5
3 3
Fe benzene,
+
Mg+
NH2
N
H3+
HO
N
N
CH2
S
O
H
H
NH
NH 2
N
O
P
OCH2
-
NN
O
O
H
H
H
CH2 O
H
H
HO
HP
O
N
O
OCH2 H
-
H
O
O
N
OH
N
O
H
H
P
OCH2
N
H H
P
O
OCH2
O
NN
HH
O
-
O
P
CH3
H
P
OCH2
O
H
OCH2H
O
-
+
H3C S
O
NH
H
O
H
S
O
N
OCH2
O
N
N
CH3
HN
OCH2
-
O
O
O
N
NH2
H
H
H
H H
P
OCH2
O
P
O
H
H
O
H
H
O
P
-
OCH2
O
O S
O
O
-
-
H
O
H
OCH2
O
CH3
O
O
H
S
N
ON O S O
H
N
Cu
NN
N
-
P
OCH2
H
H
O
O
O
NH
-
S
O
N
N
O O
Cu
O
N
S
O
ONa
N
N
N
N
OH
- S
O
O2+
S O
O
S
H
OH
H
H
ONa
N
H
O
O
OCH2
NH
O
H
H
OH
H
O
N
NH2
H
NH
NH2
O
NH2
S
N
O
S
N
H H CH3 H H O
N
N
NH
O
HO
N
N
H O
H2NH
N2
H
HN
O
N
HO
CH3
CH3
CH
3
H H
H
N
O
H
NH
OH
HO
O
O
OH
HO
O
OH
O
HO
O
O
N
OO
OH
N
S
N
H
O
N
N
O
H
O
NH2
NH
N
O
N
O
N
P
CH3
+
H3C S
O
HN
H
-
N
H
H
N
H
P
O
H
O
N
H
O
N
H
O
H
H
O-
O
O
H
O
O
CH3
HN
H
NH2
N
O
H
H
HH
OHH
OCH2
N
O
-
NH2
O
H
N
O
O
NH
N
H
O
O
O
NH2
O
P
O
H
-
CH3 H H O
N
N
O
N
O HO
N
H
H2N
H
HN
O
N
HO
CH3
CH3
CH
3
H H
H
N
O
H
NH
OH
HO
O
O
OH
HO
O
OH
O
O
O
HH
HO
N
H
H
S
N
O
H
H
O
CH3
H
O
O
OH P
-
NH2
O HN
O
O
CH3
O
HN
HH
O
O
NH2
H
H
O
O
H
H
H
H
NH2
N
O
O
NH2
N
O
H
H
NH
N
NH
N
O
O
-
H
NH2
2+
NH
OCH2
O
O
-
O
N
H
H
O
P
-
O
NH2
H
O
O
N CH3
HN
O
H
H
N
O
H
N
H
NH2
N
N
N
O
O
CH5+
Zn
N2H+
O2+, N2+
+
Ca
+
+ Zn
Ho
+
+
+
+
+
+
Ru
HCO+
C ,, Fe
, SiC(CH
, Mg
+ -,
Pb
Cr
C
H
,
C
H
CH
C
H
)
,
t-BuC
H
+
+
+
Cd
6
5
6
5
2
6
5
3
2
6
5
Si benzene,
Si naphthalene
+
Sr
3+siderophore
+
Sc
H3O+, HCNH+
Fe
+
+
+
+
W
H3+, CH
, N2+H , HCO
+ - (H
+5 Ti
DyO
HC3NH+
H3OV++ (H2O)Se
,
OH
O)
,
CH
(CH
Re
Lun+,
3
n
2
n
3+OH)
Te
+ +, HC NH+, SiC H+, SiC H +
NH2OH+
HCNH
+
Ir
102+8
3
+ 2+,4Sr
Hg
++
+ 2+, Ba
+H NCH CH COOH
Ge
Sb
C
H
O
(C
H
OH)
,
Ca
,
H
O
Zr
3
+
2
5
2
5
n
3
2
2
Ar
+, +C H +, C H+, C H +
+ +Tm
+HFe
CH
,
C
, C4H3+ +
+
+
Ga
3
2
2
2
3
3
3
3
O2
Pr Tb
Mg+++ Hf+ + Bi
+
+
+
+
+
OH-, CH3O, HCN , +HC3N ,+C60 , C60 , C60X
+ C3N Cs
Ag
Pt
+
As
H3O
Tl+
+
+
Si NH OH+, +H NCH CH Mo
La+
OH- (H2O)n
COOH
2bleomycin
+
+2 +)5-2
Pd++3(AGTCTG-5H
2+
Ta+
Gd
Ni
CH3O (CH3OH)n
+
-,+O -, OH-, OH- (H O)
Mn
Ba
O
+
+
+
2
H3O (H2O)n
Ce
Au 2Rb+n
Os+
+
+
+
C2 , C3 , CN
+
Y+ H3O++, HSm
3O +(H2O)n
+
+
+
Sn
2+
Zn penicillin
C3H3 , SiC10H8
Nd
+
Zn In
+
CH3CNH
Sr(C60)4+
FeC6H6+
Eu+
O
CH2
H
O O
H
H
HO
N
O
H
NH
O
NH2
_________________________________________________________________
“Ions are jolly little buggars, you can almost see them“
Ernest Rutherford
Looking for Ions in a Flowing Nitrogen Discharge Plasma
______________________________________________________
First quadrupole mass spectra
(in Canada)
_____________________________________________________
Mass Spectrometric Sampling Probe for Discharge Plasmas
D.K. Böhme, J.M. Goodings. Rev. Sci. Instr. 37 (1966) 362.
Ion Sampling Considerations for a Discharge Plasma of Nitrogen
D.K. Böhme, J.M. Goodings. J. Appl. Phys. 37 (1966) 4261.
Ion Chemistry in a Flowing Helium Plasma
______________________________________________________
O2+
O+
Slope = - k z/v
t = z/v
[B] >> [A+]
k
A+ + B  products
- d[A+]/dt = k [A+][B]
pseudo
1st order
kinetics
-v
d[A+]/dz
=k
[A+][B]
In He at 0.35 Torr, 296 K
(O2 + e  O+, O2+ + 2e)
O+ + H2  OH+ + H
[A+]z = [A+]z=0 exp(-k[B]z/v)
OH+ + H2  H2O+ + H
H2O+ + H2  H3O+ + H
_______________________________________________________________________________________________________________________________________________
Fehsenfeld, F. C.; Schmeltekopf, A. L.; Ferguson, E. E. “Thermal-energy ion-neutral reaction rates.
VII. Some hydrogen-atom abstraction reactions.” J. Chem. Phys. 46 (1967) 2802-8.
Getting at the Heart of Chemistry
_____________________________________________________
Plasma Ions Upstream:
e + H2O  OH- + H
e + H2O  H2O+ + 2e
H2O+ + H2O  H3O+ + OH
OH-(H2O)n + H2O + He  OH-(H2O)n+1- + He
H3O+ (H2O)n + H2O + He  H3O+ (H2O)n + He
In the complete absence of bulk solvent !
SN 2 :
Acid-Base :
OH
+ CH3Cl  Cl- + CH3OH
OH
+ CH3OH  CH3-O + H2O
H3O+ + CH3OH  CH3OH2+ + H2O
As a function of step-wise molecular solvation !
OH
(H2O)n + CH3Cl  Cl- (H2O)n + CH3OH
OH
(H2O)n + CH3OH  CH3-O (H2O)n + H2O
H3O+ (H2O)n + CH3OH  CH3OH2+(H2O)n + H2O
Transition from the Gas Phase to Solution
_____________________________________________________________
T = 298 K
OH- + CH3Cl  Cl- + CH3OH
k = 1.5 x 10-9 cm3 molecule-1 s-1!! [cf: 10-26 in H2O]
__________________________________________________________________________________________
Gas-phase reactions of anions with halogenated methanes at 297 ± 2K.
K. Tanaka, G.I. Mackay, J.D. Payzant, D.K. Bohme. Can. J. Chem. 54, 1643-59 (1976).
Bridging the gap between the gas phase and solution: transition in the kinetics of nucleophilic
displacement reactions.
D.K. Bohme, G.I. Mackay. J. Am. Chem. Soc. 103, 978-9 (1981).
Transition from the Gas Phase to Solution (cont’d)
_____________________________________________________
OH- + CH3OH  CH3O- + H2O, k = 1.5 x 10-9 cm3 molecule-1 s-1
2962 K
K = 2.2 x 107, Go = - 9.9 kcal mol-1
_______________________________________________________________
Standard acidity scale. The pKa of alcohols in the gas phase.
D.K. Bohme, E. Lee-Ruff, L.B. Young. J. Am. Chem. Soc. 93, 4608-9 (1971).
Acidity order of selected Broensted acids in the gas phase of 300K.
D.K. Bohme, E. Lee-Ruff, L.B. Young. J. Am. Chem. Soc. 94, 5153-9 (1972).
Bridging the gap between the gas phase and solution: transition in the relative acidity of
water and methanol at 296 ± 2 K. G.I. Mackay, D.K. Bohme. J. Am. Chem. Soc. 100, 327 (1978).
Proton-Transfer and Proton Affinities
__________________________________________________________
X- + YH  Y- + XH
XH+ + Y  YH+ + X
XH+ + Y  YH+ + X
________________________________________________________________________________________
Determination of proton affinities from the kinetics of proton transfer reactions. VII. The
proton affinities of O2, H2, Kr, O, N2, Xe, CO2, CH4, N2O, and CO. D.K. Bohme, G.I. Mackay,
H.I. Schiff. J. Chem. Phys. 73, 4976-86 (1980).
Selected-Ion Flow Tube (SIFT) Tandem Mass Spectrometry
______________________________________________________
Electron
Impact
M
Sifting Ions:
One Major Reactant Ion
(no Electrons)
C4H2+ + C4H2  C8H4+
 C6H2+ +
C2H2
____________________________________________________________________________________________
+
+
Studies of reactions involving C2Hx+ ions with hydrogen cyanide using a C
modified
selected
ion
flow
tube.
6H2 + C
4H2  C
10H
4
G.I. Mackay, G.D. Vlachos, D.K. Bohme, H.I. Schiff. Int. J. Mass Spectrom. & Ion Physics, 36, 259 (1980).
Ion-molecule reactions with carbon chain molecules: reactions with diacetylene and the diacetylene cation.
S. Dheandhanoo, L. Forte, A. Fox, D.K. Bohme. Can. J. Chem. 64, 641-8 (1986)
Ionic Origins of Carbenes in Space
______________________________________________________
Carbenes occur widely in the Universe
:CH2, :C=C:, :C=S, :C=O, :C =NH, :C=C=C:, l,c-:C3H2, :C3O
Their origin may involve ionizing radiation.
e + propylene  C3H+
Only H2C4: has not yet been observed in space.
________________________________________________________________
Ionic Origins of Carbenes in Space. D.K. Bohme. Nature 319, 473-4 (1986)
Synthesis of Exotic Carbon Rings
______________________________________________________
mCID
Circumstellar
Envelopes
Titan’s Atmosphere
Mg(HC3N)n-1+ + HC3N  Mg(HC3N)n+ + h, n  0
Mg(HC3N)n+ + e  (HC3N)n + Mg
Mg+
NC
NC
CN
CN
NC
+e
NC
CN
CN
+ Mg
Tetracyanocyclooctatetraene
(Tetracyanosemibullvalene)
_______________________________________________________________
Extraordinary Cluster Formation and Intramolecular Ligand-Ligand Interactions in Cyanoactylene Mediated by Mg+·:
Implications for the Atmospheric Chemistry of Titan and for Circumstellar Chemistry.
Rebecca Milburn, Alan C. Hopkinson, Diethard K. Bohme, J. Am. Chem. Soc. 127 (2005)13070-78.
Ions and Life
_______________________________________________________
NH2CH2COOH
M+ NH2CH2CH2COOH
H
M
e-
NH2CH2COOH+
NH2CH2CH2COOH+
NH3CH2COOH+
NH3CH2CH2COOH+
CH3COOH
-H2O CH3CH2COOH
h/A+
NH2OH+
Interstellar gas
Interstellar ice
h
NH3(s) + H2O(s)
CH3COOH
CH3CH2COOH -H2O
RH+
NH2OH2+
NH2OH
h, heat
NH2OH
h
NO + 3H
_______________________________________________________________________________
Gas-phase syntheses for interstellar carboxylic and amino acids.
Blagojevic et al., Mon. Not. R. Astron. Soc. 339 (2003) L7-L11.
Chemical Ionization of Fullerenes
_____________________________________________
Penning Ionization
He (3S1, 1S1) + C60  He(1S0) + C60+• + e
“Electron Transfer/ Electron Detachment”
He+ + C60  C602+ + He + e
“Double-Electron Transfer/ Electron Detachment”
Ar2+ + C60  C60•3+ + Ar + e
_______________________________________________________________________________
Fullerene Cation and Dication Production by Novel Thermal-Energy Reactions of
He+, Ne+, and Ar+ with C60. G. Javahery, S. Petrie, J. Wang and D.K. Bohme. Chem.
Phys. Lett., 195, 7-10 (1992).
Electron-Transfer Reactions with Buckminsterfullerene, C60, in the Gas Phase.
D.K. Bohme, Int. Reviews in Physical Chemistry, 13, 163-185 (1994).
Playing Chemistry with Buckyballs
____________________________________________________
C60+•
C602+
_____________________________________________________________________________________________________
Derivatization of the Fullerene Dications C602+ and C702+ by Ion-Molecule Reactions in the Gas Phase.
S. Petrie, G. Javahery, J. Wang and D.K. Bohme. J. Am. Chem. Soc., 114, 9177-9181 (1992).
Gas-Phase Reactions of the Buckminsterfullerene Cations C60.+, C602+ and C60.3+ with Water, Alcohols and
Ethers. R. Javahery, S. Petrie, H. Wincel, J. Wang and D.K. Bohme. J. Am. Chem. Soc., 115, 6295-6301 (1993).
Charge ………!
___________________________________________________________
C603+•
______________________________________________________________________
Gas-Phase Reactions of Fullerene Monocations, Dications and Trications with Nitriles.
G. Javahery, S. Petrie, J. Wang, H. Wincel and D.K. Bohme. J. Am. Chem. Soc., 115, 9701-9707 (1993).
Chemistry as a Function of Charge State
_________________________________________________________________
Chemistry is increasingly pre-empted by physics (e transfer)
with increasing charge state.
_______________________________________________________________________
Fullerene Ions in the Gas Phase: Chemistry as a Function of Charge State.
D.K. Bohme, Can. J. Chem. 77, 1453-1464 (1999).
Gas-Phase Surface Chemistry
____________________________________________________
The Influence of Curvature (Strain)
(C surface)+ + c-C5H6  addition
Metal-Cation Ligation
on Curved Carbonaceous Surfaces
+
H
Fe
H
+
Fe
+
Fe
H
H
H
H
H
+
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Fe
H
H
H
H
+
Fe H
H
H
H
H
H
_____________________________________________________________________________________________________________________
The Influence of Surface Strain on the Chemical Reactivity of Fullerene Ions: Addition Reactions with
Cyclopentadiene and 1,3-Hexadiene.. Becker, L.T. Scott and D.K. Bohme, Int. J. Mass Spectrom. Ion Processes
167/168, 519 (1997).
Enhanced Reactivity of Fullerene Cations Possessing Adjacent Pentagons. S. Petrie and D.K. Bohme.
Nature, 365, 426. (1993).
The ICP/SIFT/QqQ instrument
_____________________________________________________
Argon Plasma
T
u
rb
o
P
u
m
p
P
l
a
s
m
a
S
o
u
rc
e
H
e
u
i
l
m
I
n
e
lt
R
e
a
g
e
n
t
I
n
e
lt
B
o
l
w
e
r
T
ri
p
e
l
Q
u
a
d
ru
p
o
e
l
5500 K
P = 1 atm
D
u
f
i
s
o
i
n
P
u
m
p
T
u
rb
o
P
u
m
p
T
u
rb
o
P
u
m
p
Aqueous solution
of the atomic salt
is injected via a
nebulizer into
the Ar plasma
__________________________________________________________________________________________________________
An Inductively-Coupled Plasma / Selected-Ion Flow Tube Mass Spectrometer Study of the Chemical Resolution of Isobaric
Interferences. G.K. Koyanagi, V.I. Baranov, S. Tanner and D.K. Bohme, J. Anal. At. Spectr. 15, 1207-1210 (2000).
Periodic Table of Atomic Salt Solutions
Reactions of atomic cations: Nb+ with N2O
______________________________________________________
103
Nb+ NbO2+
NbO2+·(N2O)2
NbNO+·(N2O)2
Ion Signal
102
NbO2 ·(N2O)3
+
+
NbO2 ·N2O
+
NbNO
Primary Oxidation and Nitration
Nb+ + N2O  NbO+ + N2
 NbN+ + NO
Further Oxidation
NbO+ + N2O  NbO2+ + N2
NbN+ + N2O  NbNO+ + N2
Clustering with N2O
NbO+
101
NbNO+·N2O
NbNO+·(N2O)3
NbN+
NbO2+ + N2O  NbO2(N2O)+
NbO2(N2O)+ +N2O NbO2(N2O)2+
NbO2(N2O)2+ +N2O NbO2(N2O)3+
NbNO+ + N2O  NbNO(N2O)+
NbNO(N2O)+ +N2ONbNO(N2O)2+
0.0
1.0
2.0
3.0
4.0
NbNO(N2O)2+
N2O flow/(1017 molecules s-1)
+N2ONbNO(N2O)3+
________________________________________________________________
V.V. Lavrov et al., J. Phys. Chem. A 106 (2002) 4581.
100
Surfing the Periodic Table with N2O
______________________________________________________
M+ + N2O
 MO+ + N2
 MN+ + NO
 M+(N2O)
________________________________________________________________
V.V. Lavrov et al., J. Phys. Chem. A 106 (2002) 4581.
Barriers to Electron Promotion
____________________________________________________
Ln+ + N2O  LnO+ + N2
10-10
20
40
10-11
60
80
10-12
100
4f n5d06s1  4f n-15d16s1
k/(cm3 molecules-1 s-1)
0
Promotion Energy/(kcal mol-1)
10-9
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
_____________________________________________________
G.K. Koyanagi, D.K. Bohme. J. Phys. Chem. A 105, 8964 (2001).
Arrhenius would be interested!
____________________________________________________
kexp= kc e-PE/RT
Web data base
61 atomic cations x 15 molecules = 915 reactions !!
http://www.chem.yorku.ca/profs/bohme/research/research.html
Chemical Resolution in Elemental Analysis
____________________________________________________
The 87Rb+ (s0) / 87Sr+ (s1) Isobaric Interference
Rb+ (s0) + SF6  NR
k  1x10-13 cm3 s-1
Sr+ (s1) + SF6  SrF+ + SF5 97%
 SrSF5+ + F
3%
k = 5.7x10-10 cm3 s-1
Discontinuities in Reactivity: Opportunities for Chemical
Resolution
____________________________________________________
M+ + SF6
 MFn+ + SF6-n
 M+(SF6 )
 SFn+ + MF6-n
____________________________________________________
C. Ping and D.K. Bohme, J. Phys.Chem. A, in preparation.
Atomic Ions: the Ultimate Sites for Catalysis
_____________________________________________
Catalytic Reduction of NxOy by CO
Catalytic
reduction
of NxO
y by CO
(O-atom
Transport
Mediated
by M+)
NO2
(2) NO
N2O
N2
M+
MO+
M+
MO+
M+
MO+
CO2
CO
CO2
CO
CO2
Observed
Observed with:
with:
Fe+, Ge+
Fe+, Ge+
+
Sr
Sr+
+, Os+, Ir+
Ba
+
+
Ba , Os , Ir+
Eu+, Yb+Eu+, Yb+
CO
____________________________________________________
____________________________________________________
Blagojevic et et
al.,Angew.
Chem.Chem.
Int. Ed. 2003,
42, 2003,
4923-4927
Blagojevic
al., Angew.
Int. Ed.
42, 4923-4927
Potential Energy Landscape for Catalysis
______________________________________________________
N2O + CO  N2 + CO2
TS
H /kcal mol-1
CO
N2O
6D Fe+
0.9
14.9
CO
47.2
TS
N2
CO
61.8
0.9
CO
22.9
30.6
64.1
CO
N2
N
O Fe+ + N2O  FeO+ + N2
C
N2
Fe
GAUSSIAN98 B3LYP/sdd/6-311+G*
86.7
TS
47.8
CO2
N2
6D Fe+
FeO+ + CO  Fe+ + CO2
__________________________________________________________________
V. Blagojevic, G. Orlova, D. K Bohme, J. Am. Chem. Soc. 127 (2005) 3545.
Packing Atomic Metal Cations with C60
_____________________________________________________
10
10
6
Sr
+
SrC60
+
5
Intensity
Sr(C60)2
10
4
10
3
10
2
10
1
10
0
+
Sr(C60)3
+
Sr(C60)4
0
500
1000
1500
2000
2500
+
3000
m/z
ICP/SIFT/QqQ mass spectrum
Proposed tetrahedral
structure for Sr(C60)4+
_______________________________________________________________________
G.K. Koyanagi, J. Xu and D. K. Bohme, unpublished
The ESI/qQ/SIFT/QqQ instrument
_____________________________________________________
A – skimmer, B – q0 reaction cell, C extended stubbies, D – extended q0 rod set
_________________________________________________________________________________________
A novel chemical reactor suited for studies of biophysical chemistry: construction and
evaluation of a selected ion flow tube utilizing an electrospray ion source and a triple
quadrupole detection system. G.K. Koyanagi et al. Int. J. Mass Spectrom. In press, 2007.
From Atomic Dications….
_____________________________________________________
Oxidation of Ca++ Initiated by Charge Separation.
Ca
++
+
Ca++ + O3  CaO+ + O2+
O2
+
CaO
CaO3
10
-1
Ion Signal/(s )
(k = 1.5 × 10-9 cm3 mol-1 s-1)
+
3
+
CaO2
CaO+ + O3  CaO2+ + O2
2
(k = 5 × 10-10 cm3 mol-1 s-1)
10
0
1
2
3
4
17
5
6
-1
O3 flow/(10 molecules s )
100 M CaAcetate in H2O/CH3OH (1/1)
7
CaO2+ + O3  CaO3+ + O2
(k = 6 × 10-10 cm3 mol-1 s-1)
…..to DNA
_______________________________________________________________________________
Protonation and Hydrobromination
of (AGTCTG-5H)5-
4
50 M in 20/80 CH3OH/H2O
10
NH2
N
N
N
O
H
3
H
H
O
H
H
N
O
O
P
NH
OCH2
N
-
H
+ HBr
NH2
N
O
O
H
H
7
3
6
4
n= 1 [(AGTCTG-4H)(HBr)n ]
2
10
5
n= 1 [(AGTCTG-2H)(HBr) n ]
1
10
2
(AGTCTG-5H)
(AGTCTG-4H)
O
H
H
(AGTCTG-3H)
CH3
O
5
n=1 [(AGTCTG-3H)(HBr)n ]
10
1
CH2
N
Ion Signal/(s )
HO
7
n= 1 [(AGTCTG-5H)(HBr)n ]
(AGTCTG-2H)
HN
5
4
3
2
0
O
P
OCH2
-
O
10
O
O
0.0
N
H
H H
kobs kobs/kc
N
O
P
0.8
HBr flow/(10
H
H
O
0.4
NH2
OCH2
O
3.2
N
O
-
O
H
H
O
H
H
O
H
O
P
-
OCH2
O
CH3
HN
O
O
2.6
H
-
OCH2
O
H
1.6
1
molecules s )
27%
[(AGTCTG − 5H)(HBr)n]5−
n = 1-7
HBr
4–
16%
[(AGTCTG − 4H)(HBr)n]4−
n = 1-6
HBr
O
N
H
O
73%
84%
H
H
P
0.78
N
H
O
0.68
5–
17
1.2
N
O
H
H
OH
H
H
1.9
NH
N
0.77
NH2
3–
20%
1.3
0.80
x10-9 cm3 s-1
80%
[(AGTCTG − 3H)(HBr)n]3−
n = 1-7
HBr
2–
100%
[(AGTCTG − 2H)(HBr)n]2−
n = 1-5
Acknowledgments
Greg Koyanagi
Stefan Feil
Janna Anichina
Voislav Blagojevic
Michael Jarvis
Andrea Dasic
Tuba Gozet
Sara Hashemi
Mike Duhig
Svitlana Shcherbyna