1
SUPPORTING INFORMATION
S
ynthesis
and
Electronic
P
roperties
of Nitrogen
-
Rich Nanographenes
Gavin P. Heim, Masanari Hirahara, Vidhya Dev, and Theodor Agapie*
Division of Chemistry and Chemical
Engineering, California Institute of Technology,
1200 E California Blvd MC
127
-
72,
Pasadena, California 91125, United States
Table of Contents
General Considerations
2
Synthetic Procedures
2
Synthesis of
5
-
bromo
-
2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidine (1a)
3
Figure S1.
1
H NMR of
5
-
bromo
-
2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidine (1a)
4
Figure S2.
13
C NMR of
5
-
bromo
-
2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidine (1a)
4
Synthesis of
1,2
-
bis(2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidin
-
5
-
yl)ethyne
(
2
a)
5
Figure S3.
1
H NMR of
1,2
-
bis(2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidin
-
5
-
yl)ethyne
(
2
a)
6
Figure S4.
13
C NMR of
1,2
-
bis(2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidin
-
5
-
yl)ethyne
(
2
a)
6
Synthesis of
1,2,3,4,5,6
-
hexakis(2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidin
-
5
-
yl)benzene
(3a).
7
Figure S5.
1
H NMR of
1,2,3,4,5,6
-
hexakis(2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidin
-
5
-
yl)benzene
(3a)
8
Figure S6.
13
C NMR of
1,2,3,4,5,6
-
hexakis(2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidin
-
5
-
yl)benzene
(3a)
8
General strategy for monitoring the ring closure of 3a and 3b
9
Synthesis
of
H
P
C
-
N
12
(Ar
tBu
)
6
9
Figure S7.
1
H NMR of
H
P
C
-
N
12
(Ar
tBu
)
6
10
Figure S8.
13
C NMR of
H
P
C
-
N
12
(Ar
tBu
)
6
10
Additional Electrochemistry/Spectroscopy Data
11
Figure S9.
Cyclic voltammogram of
H
P
C
-
N
12
(Ar
tBu
)
6
11
Figure S10.
Absorption and emission
spectr
a
of
H
P
C
-
N
12
(Ar
tBu
)
6
with ZnCl
2
12
Figure S11.
Absorption and emission
spectr
a
of
H
P
C
-
N
12
(Ar
tBu
)
6
with TfOH
13
Figure S12.
E
mission
spectr
a
of
H
P
C
-
N
12
(Ar
tBu
)
6
with CuBr
2
14
Figure S13.
Absorption
spectr
a
of
H
P
C
-
N
12
(Ar
tBu
)
6
with CuBr
2
14
Figure S14.
MALDI
-
TOF of ZnCl
2
added to
HPC
-
N
12
(Ar
tBu
)
6
in CHCl
3
15
Figure S15.
MALDI
-
TOF of
CuBr
2
added to
HPC
-
N
12
(Ar
tBu
)
6
in
THF
15
Table S1.
Comparing redox features in HBC variants
16
Density Functional Theory Calculations
17
Figure S16.
Geometry
-
optimized structures of
H
P
C
-
N
12
Ph
6
17
Figure S17.
Geometry
-
optimized structures of
HBC
-
Ph
6
17
Figure S18.
HOMO, HOMO
-
1, LUMO, and LUMO+1 of
H
P
C
-
N
12
Ph
6
18
Figure S19.
HOMO
-
6 and HOMO
-
2 for
H
P
C
-
N
12
Ph
6
. Isovalues set to 0.02
19
Figure S20.
HOMO, HOMO
-
1, LUMO, and LUMO+1 of
HBC
-
Ph
6
20
Figure S21.
HOMO
-
2 for
HBC
-
Ph
6
. Isovalue set to 0.02
21
Table S
2
.
HOMO
-
LUMO energy differences (B3LYP/6
-
311G(d,p))
22
Table S3.
Cartesian coordinates obtained for the optimized geometry of
H
P
C
-
N
12
22
Table
S
4
.
Cartesian coordinates obtained for the optimized geometry of
H
P
C
-
N
12
Ph
6
23
Table S
5
.
Cartesian coordinates obtained for the optimized geometry of
HBC
-
Ph
6
25
Table S
6
.
Cartesian coordinates obtained for the optimized geometry of
HBC
-
Ph
6
(90º)
27
Table S
7
.
Cartesian coordinates obtained for the optimized geometry of
HBC
-
Ph
6
(45º)
30
Crystallographic Information
33
Refinement Details
34
Table S
8
.
Crystal data and structure refinement for
H
P
C
-
N
12
(Ar
tBu
)
6
3
4
Table S
9
.
Comparison of select bond lengths
3
5
Figure S22.
Additional representations of
H
P
C
-
N
12
(Ar
tBu
)
6
crystal structure
3
6
References
3
7
Electronic
Supplementary
Material
(ESI)
for
Chemical
Communications.
This
journal
is
©
The
Royal
Society
of
Chemistry
2024
2
General
c
onsiderations
.
Unless otherwise specified, all operations involving air
-
or water
-
sensitive
reagents were carried out in an MBraun drybox under a nitrogen atmosphere or using standard Schlenk and
vacuum line techniques. Glassware was oven
-
dried at 140 ºC for 2 h prior to
use on the Schlenk line or in
the MBraun drybox. Tetrahydrofuran (THF), diethyl ether, toluene, pentane, and hexanes for air
-
and
moisture
-
sensitive reactions were dried by the method of Grubbs.
1
Dry
N,N
-
dimethylformamide (DMF)
was purchased from Millipore Sigma and cannula transferred to freshly
-
activated 3 Å molecular sieves and
stored in a Teflon
-
sealed Schlenk tube under N
2
atmosphere for 12 h prior to use.
Meta
-
xylene w
as
vacuum
transferred from sodium benzophenone ketyl. Deuterated solvents were purchased from Cambridge Isotope
Laboratories and
CDCl
3
was used as received.
All solvents, once dried and degassed, were stored under a
nitrogen
atmosphere
over
3
Å
molecular
sieves.
Iodo[b
is(dipheny
lphosphino)
-
9,9
-
dimethylxanthene]copper(I)
w
as
prepared following
a
previously reported procedure.
2
All other reagents
were used as received.
1
H, and
13
C{
1
H} spectra were recorded on Varian Mercury 300 MHz or Varian 400
MHz spectrometers at ambient temperatures, unless otherwise denoted.
1
H
and
13
C{
1
H} NMR spectra are
reported referenced internally to residual solvent peaks reported relative to tetramethylsilane. Gas
chromatography
-
mass spectrometry (GC
-
MS) were performed on an Agilent 6890A instrument using a
HP
-
5MS column (30 m length, 0.25 mm diame
ter, 0.50 μm film) and an Agilent 5973N mass
-
selective
EI
detector.
Absorption
spectra were recorded on a Varian Cary Bio 50 spectrophotometer.
Electrochemical measurements:
CVs were recorded with a Pine Instrument Company AFCBP1
biopotentiostat with the AfterMath software package. All measurements were performed in a three
electrode cell, which consisted of glassy carbon (working; ø = 3.0 mm), silver wire (counter) and bare
platinum wire (reference), in a
n
N
2
-
filled MBraun glovebox at RT. Dry tetrahydrofuran that contained ~100
mM [
n
Bu
4
N
][PF
6
] was used as the electrolyte solution. The ferrocene/ferroc
e
nium (Fc
H
/Fc
H
+
) redox wave
was used as an inte
rnal
standard for all measurements.
Preparation of pre
-
reduced magnetic stir bars:
Sodium mirror (10
-
20 mg) is prepared in a 20
-
mL
scintillation vial along with 200
-
300 mg of benzophenone dissolved in THF to form a purple solution,
which is then added to a
20
-
mL vial containing 10
-
20 Teflon
-
coated magnetic stir bars
and stirred for 12 h.
The solution is decanted, and the stir bars are rinsed
with THF
until the mother liquor is colorless, resulting
in black, pre
-
reduced magnetic stir bars
that are dried under vacuum for 1 h and are
to be used for reactions
involving Na
and
Na
K.
Absorption spectroscopy
:
UV
-
vis
spectra were recorded on a Varian Cary Bio 50 spectrophotometer
in a
1 mm cuvette. Single equivalents of ZnCl
2
(103 mM in CHCl
3
) were added to 0.060 mM
HPC
-
N
12
(Ar
tBu
)
6
.
After addition of an equivalent, a spectrum was recorded.
Emission
spectroscopy
:
Corrected room temperature emission spectra were collected in the Beckman
Institute Laser Resource Center using a modified Jobin Yvon Spec Fluorolog
-
3 instrument. Samples were
excited with a xenon arc lamp, employing a monochromator for wavelength selectio
n, and emission was
detected at 90° using two Ocean Optics EQDPro CCD spectrometers spanning 300
–
930 nm
.
Single
equivalents of
metal salt or trifluoromethane sulfonic acid
(103 mM) were added to 0.060 mM
HPC
-
N
12
(Ar
tBu
)
6
. After additi
on of an equivalent, a spectrum was recorded.
The entrance and exit slits were 5
nm, and voltage was set to 400 V.
MALDI
-
TOF:
Mass spectra were recorded on a Bruker Autoflex MALDI TOF/TOF. Dithranol (0.091
mM in CHCl
3
) was employed as the matrix. 3 μL of the dithranol solution were combined with 1 μL of
0.060 mM
HPC
-
N
12
(Ar
tBu
)
6
+
metal salt mixture.
This mixture was drop casted onto a MALDI plate and
allowed to dry under ambient conditions.
3
Synthe
tic Procedures
5
-
B
romo
-
2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidine (1
).
Adapted from a previously
-
reported procedure:
3
In
an N
2
-
purged glove box,
a Schlenk
flask fitted with a screw
-
in Teflon stopper was charged with a solution
of 3,5
-
di
-
tert
-
butylbromobenzene (20 g, 75 mmol) in THF (250 mL). The flask was sealed
,
brought outside
of the box and cooled to
–
78 °C with a dry ice/acetone bath. A pentane solution of tert
-
butyllithium (80
mL, 2.0 M, 160 mmol) was added dropwise via cannula. The reaction was allowed to warm to room
temperature and stirred for 1 h forming
a yellow solution. The reaction was then brought
back
into an N
2
-
purged glovebox and ZnCl
2
(7.2 g
, 53 mmol) was added slowly to the reaction resulting in the loss of the
yellow coloration
and formation of a white precipitate
. The mixture was allowed to stir at room temperature
for 30 min. 5
-
bromo
-
2
-
iodopyrimidine (22.3 g, 78 mmol) was added to the mixture. The flask was then
placed in
a
cold well
previously cooled with liquid nitrogen.
Pd(PPh
3
)
4
(1.3 g, 1.0 mmol) was added slowly,
the flask sealed, and brought outside of the box. The vessel was fitted with an oven
-
dried reflux condenser
and warmed to 7
0 °C for 12 h. After cooling to room temperature, water (
10
0 mL) was added to quench
the reaction, and the mixture concentrated in vacuo to about 100 mL. The resulting suspension was taken
up in CH
2
Cl
2
(200 mL) and washed with 5 x 100 mL of water. The organic layer was washed with brine (2
x 100 mL), dried over MgSO
4
, and filtered. Removal of the volatiles under a reduced pressure afforded an
orange solid, which was charged with 200 mL of hexanes and heated to reflux. The mixture was filtered,
and the filtr
ate was concentrated under a reduced pressure, allowing a white solid to crash out, which was
filtered and washed with cold hexanes. The off
-
white solid
(
15
.2
g
,
5
7.5
% yield)
is
analytically pure
1a.
1
H
NMR
(400 MHz, CDCl
3
):
d
= 8.84 (s, 2H, Ar
H
), 8.31 (app d, 2H, Ar
H
), 7.62 (t, 1H, Ar
H
), 1.43 (s, 18H,
C(C
H
3
)
3
)
.
13
C{
1
H} NMR (101 MHz, CDCl
3
)
d
=
163.75 (aryl
-
C
), 157.84 (aryl
-
C
), 151.40 (aryl
-
C
), 135.93
(aryl
-
C
), 125.6 (aryl
-
C
), 122.65 (aryl
-
C
), 118.05
(aryl
-
C
), 35.18
(
C
(CH
3
)
3
)
, 31.64
(
C
(
C
H
3
)
3
)
. HRMS
(FAB+) m/z Calcd. for
[M + H
+
]
C
18
H
13
BrN
2
347.1123, found 347.1122.
4
Figure S1.
1
H NMR spectrum (400 MHz, CDCl
3
) of
5
-
bromo
-
2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidine
(1
)
.
Figure S2.
1
3
C{
1
H}
NMR spectrum (101 MHz, CDCl
3
) of
5
-
bromo
-
2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidine
(1
)
.
3
0
3
5
4
0
4
5
5
0
5
5
6
0
6
5
7
0
7
5
8
0
8
5
9
0
9
5
1
0
0
1
0
5
1
1
0
1
1
5
1
2
0
1
2
5
1
3
0
1
3
5
1
4
0
1
4
5
1
5
0
1
5
5
1
6
0
1
6
5
f
1
(
p
p
m
)
3
1
.
6
4
3
5
.
1
8
7
7
.
1
6
C
D
C
l
3
1
1
8
.
0
5
1
2
2
.
6
5
1
2
5
.
6
0
1
3
5
.
9
3
1
5
1
.
4
0
1
5
7
.
8
4
1
6
3
.
7
5
5
1,2
-
bis(2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidin
-
5
-
yl)ethyne (2
).
Adapted from a previously
-
reported
procedure:
4
A 1
-
L, oven
-
dried Schlenk flask was allowed to cool under vacuum on the Schlenk line. Under
a positive pressure of N
2
, the Schlenk flask was charged with
5
-
bromo
-
2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidine (
1a
) (12.8 g, 37 mmol), cesium carbonate (24.1 g, 74 mmol), and palladium (II)
acetate (165 mg , 0.73 mmol). DMF (250 mL) was added to the Schlenk flask via cannula. To this mixture
was added trimethylsilylacetylene (3.14 mL, 22 mmol) under positive N
2
pressure
. The reaction mixture
was
degassed
via
one
cycle
of
freeze
-
pump
-
thaw.
Iodo[
b
is(diphenylphosphino)
-
9,9
-
dimethylxanthene]copper(I) (566 mg, 0.73 mmol) was added under positive N
2
pressure
. The reaction
mixt
ure was subject
ed
to two more cycles of freeze
-
pump
-
thaw, and the mixture was heated to 60 ºC for
12 h. Volatiles were removed under a reduced pressure, and the crude solid was charged with CH
2
Cl
2
(300
mL) and filtered to remove excess cesium carbonate. The filtrate was concentrated under a reduced pressure
and purified via column chromatography with CH
2
Cl
2
as the eluent. The white solid
(5
.3
g,
25.6
%)
was
dried under vacuum for 12 h at room temperature prior to the next step.
1
H NMR (400 MHz, CDCl
3
)
d
=
8.95 (s, 4H, Ar
H
), 8.36 (app d, 4H, Ar
H
), 7.61 (t, 2H, Ar
H
), 1.42 (s, 36H, C(C
H
3
)
3
).
13
C{
1
H} NMR (101
MHz, CDCl
3
)
d
= 164.02 (aryl
-
C
), 159.13 (aryl
-
C
), 151.45 (aryl
-
C
), 136.22 (aryl
-
C
), 125.93 (aryl
-
C
),
123.02 (aryl
-
C
), 115.89 (aryl
-
C
), 90.03 (alkyne
-
CC
), 35.22 (
C
(CH
3
)
3
)
31.65 (C(
C
H
3
)
3
)
. HRMS (FAB+) m/z
Calcd. for
[M + H
+
]
C
38
H
47
N
4
559.3801, found 559.3813.
6
Figure S3.
1
H NMR spectrum (400 MHz, CDCl
3
) of
1,2
-
bis(2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidin
-
5
-
yl)ethyne
(2
)
.
Figure S4.
13
C{
1
H} NMR
spectrum (101 MHz, CDCl
3
) of
1,2
-
bis(2
-
(3,5
-
di
-
tert
-
butylphenyl)pyrimidin
-
5
-
yl)ethyne
(2
)
.
3
0
3
5
4
0
4
5
5
0
5
5
6
0
6
5
7
0
7
5
8
0
8
5
9
0
9
5
1
0
0
1
0
5
1
1
0
1
1
5
1
2
0
1
2
5
1
3
0
1
3
5
1
4
0
1
4
5
1
5
0
1
5
5
1
6
0
1
6
5
f
1
(
p
p
m
)
3
1
.
6
5
3
5
.
2
2
7
7
.
1
6
C
D
C
l
3
9
0
.
0
3
1
1
5
.
8
9
1
2
3
.
0
2
1
2
5
.
9
3
1
3
6
.
2
2
1
5
1
.
4
5
1
5
9
.
1
3
1
6
4
.
0
2