Three in one: prototropy-free highly stable AADD-type self-complementary quadruple hydrogen-bonded molecular duplexes with a built-in fluorophore

Article abstract of DOI:10.1039/C6CC09478C

This communication reports an effective approach for addressing the prototropy-related problems in heterocycle-based AADD-type self-assembling systems by freezing their hydrogen-bonding codes, by utilizing intramolecular bifurcated hydrogen bonding interactions. Using this strategy, we have also developed a hydroquinone-conjugated AADD-type self-assembling system adorned with three valuable features such as prototropy-free dimerization yielding single duplexes, high duplex stability and a built-in fluorophore, which would augment its application potential. The rational approach used herein to arrest prototropic shift may also find application elsewhere, wherein proton shift-mediated structural changes become a detrimental factor.

Full text of DOI:10.1039/C6CC09478C

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Three in One: Prototropy-free Highly Stable AADD-type Self-
Complementary Quadruple Hydrogen-Bonded Molecular
Duplexes with Built-in Fluorophore†‡
Received 00th January 20xx,
Accepted 00th January 20xx
Sanjeev Kheria,a Suresh Rayavarapu,a Amol S. Kotmale,b and Gangadhar J. Sanjayan*a
DOI: 10.1039/x0xx00000x
www.rsc.org/
This communication reports an effective approach for addressing led to the development of different types of the hydrogen-
the prototropy-related problems in heterocycle-based AADD-type bonding motifs devoid of tautomerization which will be
self–assembling systems by freezing their hydrogen-bonding promising candidates for diverse applications.
codes, by utilizing intramolecular bifurcated hydrogen bonding
(a)
(b)
(c)
O
R
O
R
H
interactions. Using this strategy, we have also developed a
hydroquinone-conjugated AADD-type self-assembling system
adorned with three valuable features such as prototropy-free
dimerization yielding single duplex, high duplex stability and a
built-in fluorophore, which would augment its application
potential. The rational approach used herein to arrest prototropic
shift may also find application elsewhere, wherein proton shift-
mediated structural changes become a detrimental factor.
H
H
N
N
O
N
O
N
O
R
R
R
O
N
N
H
N
H
O
N
N
H
N
H
N
N
N
H
N
H
H
N
H
N
H
N
H
N
H
N
H
N
N
O
R
N
O
N
N
R
R
R
O
N
N
O
N
O
N
H
H
H
R
O
O
Kdim > 107 M-1
Kdim > 106 M-1
Kdim > 107 M-1
Triazine-based duplex
(insensitive to prototropy)7
Note: Prototropy arrested using
degenerate prototropy
Dezapterin duplex
(sensitive to prototropy) 5
Ureidopyrimidinone duplex
(sensitive to prototropy)3a
Quadruple hydrogen bonding systems have triggered wide
research interest in the design and developmemt of well-
defined supramolecular architectures1 due to their high
strength, specificity, directionality and reversibility. Various
heterocycle-based multiple hydrogen-bonding modules were
developed and have shown good application potential.2 These
systems, most often urea derivatives, are inspired by Nature’s
use of DNA base pairs such as purines and pyrimidines. In
particular, Meijer’s ureidopyrimidone3 (UPy) system, due to its
easy synthetic accessibility and high dimerization constant
(Kdim > 107 M-1), has found extensive application in various
fields such as supramolecular chemistry, material science, and
catalysis (Fig. 1a).4 A closely-related deazapterin-based self-
assembling system also shows high duplex stability (Fig. 1b).5
Fig 1. AADD-type self-assembling systems forming highly stable duplexes.
Recently, our group has reported a new class of triazine-
based highly stable AADD-type self-assembling systems devoid
of prototropy - without compromising duplex stability (Fig.
1c).7 These systems have high dimerization constant in apolar
solvent (Kdim > 107 M-1 in CDCl3).
For the development of self-complementary systems featuring
high Kdim, but without prototropy-related issues, herein we
propose an effective strategy to address the prototropy issues
associated with heterocycle-based AADD-type quadruple
hydrogen-bonding modules by freezing their H-bonding codes,
by exclusively using intramolecular bifurcated hydrogen
bonding interactions (Fig. 2, vide supra). It was envisaged that
the “enol prototropy”, usually associated with heterocycle-
based quadruple hydrogen-bonding systems, will not occur in
the designed systems, primarily because of the H-bonding
“locking” mechanism, which would effectively prevent the
crucial proton shift leading to the enol form. As a proof-of-
It is noteworthy that heterocycle-based AADD-type self-
assembling systems are associated with prototropy-related
issues and as a result, the protamers (keto and enol forms)
generate different structures – both in solution- and solid-
state.3a Continuous research in this area by various groups6 has
principle, we have developed 1, wherein the methoxy group
acts as a H-bonding acceptor, in conjunction with the urea
carbonyl group (another H-bonding acceptor), to arrest the
labile pyrimidine ring N-H (H-bonding donor) from shifting its
position. Thus, proton shift is effectively arrested leading to
the formation of a single set of molecular duplex. Using the
same principle, quinoline derivative
2 was also developed,
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wherein the quinoline ring nitrogen participates in bifurcated type H-bonding code, possibly because the free phenol would
H-bonding. The hydroquinone derivative is a close analog of stabilize the pyrimidine ring in its aromatized form, owing to
, except that it is adorned with fluorescent properties. protonation of the pyrimidine nitrogen. However, this
opportunity does not exist in its oxidized form
3
1
4
.
O
A
H
A
H
A
H
D
A
D
A
O
H
O
H
N
H
D
A
N
O
N
O
N
O
R
R
R
O
N
3
N
H
N
O
N
1
N
H
N
O
N
2
N
H
N
H
H
H
A
A
D
D
D
A
A
D
D
A
A
D
Ketoꢀform stabilized
Ketoꢀform stabilized
Ketoꢀform stabilized
Selfꢀ
Selfꢀ
Selfꢀ
Assembly
Assembly
Assembly
O
O
H
O
H
N
H
N
N
O
N
N
O
N
O
R
R
R
O
N
N
H
N
H
O
N
N
H
N
H
O
N
N
H
N
H
A A D D
D A A
A A D D
D D A A
H
N
H
N
H
N
H
N
H
N
H
N
D
N
O
N
O
N
O
R
R
R
O
O
O
N
H
O
H
O
H
N
O
1—1
2—2
3—3
K
dim > 107 Mꢀ1 in CDCl3
Modified ureidopyrimidinone-based duplexs, insensitive to prototropy (This work)
Note: Prototropy issue arrested using intramolecular bifurcated H-bonding
Fig 2. Design strategy to arrest prototropy using bifurcated hydrogen-bonding.
The urea intermediate
process (Scheme 1). The dichloro amino pyrimidine
by reacting 2-amino-4,6-dihydroxypyrimidine with POCl3 and
Et3N under reflux condition, was converted to its isocyanate 79
by treatment with oxalyl chloride, in refluxing benzene. The
highly reactive and unstable isocyanate was treated with 2-
ethylhexylamine at room temperature to afford the urea
intermediate , which could be coupled with various boronic
acids under standard Suzuki coupling conditions to furnish
12a . Direct conversion of 12a to , by hydrolysis of chloro
8
was synthesized by a three-step
Scheme 1 Synthesis of compounds 1, 2 and 3. Reagents and conditions: (i) POCl3,
6, obtained
Et3N, CH3CN, reflux, 1h; (ii) a) (COCl)2, C6H6, reflux, 2h, b) 2-ethylhexylamine,
C6H6, RT, 18h; (iii) Pd(PPh3)4, Na2CO3, DME/H2O (3:1), 110oC, 12h; (iv) K2CO3,
CH3OH, reflux, 6h; (v) HBr/AcOH, reflux, 1h.
5
,
7
8
-c
-c
1-3
substituent did not yield a tangible result. Therefore, we
adopted an alternative two-step strategy in which the chloro
of 12a
HBr/acetic acid condition, resulting in good yields of
We also had an interest to synthesize a potential redox-active
quinone analog (Scheme 1), starting from by
-c was methoxylated followed by demethylation under
1-3.
4
3,
demethylation followed by oxidation or hypervalent iodine-
mediated oxidative de-aromatization.10 However, all our
efforts in this direction failed, since intractable mixture of
products were obtained. Therefore, we sought an alternate
Scheme 2 Attempted synthesis of 4. Reagents and conditions: (i) BnBr, K2CO3,
acetone, reflux, 24h; (ii) (CH3O)2CO, NaH, 75oC, 24h; (iii) guanidine carbonate,
C2H5OH, reflux, 20h; (iv) 2-ethylhexyl isocyanate, pyridine, 100oC, 10h; (v) Pd/C,
THF, H2, balloon, 24h.
strategy to synthesize
4, starting from 14 (Scheme 2).
Although self-assembling systems
analogs, exhibited fluorescence owing to the presence of the
hydroquinone moiety.8 Therefore,
was taken up as a
representative case for extensive structural studies. Further,
compounds and
showed similar 1H NMR chemical shift
values for their urea NHs, suggesting similar H-bonding
arrangements in the duplex. Full characterization data of is
provided (ESI, page S14-S16).
The duplex formation by
1 and 3 are close
Following literature procedures, 14 was bis-benzylated to yield
15, followed by its reaction with dimethyl carbonate to obtain
the active methylene compound 16, which reacted with
guanidine carbonate to furnish 17. The amino pyrimidine 17
could be efficiently converted to its benzyl protected urea
analog 18 by reacting with 2-ethylhexyl isocyanate.
Hydrogenation of 18 readily afforded its free hydroquinone
derivative 19. Quite unfortunately, all our extensive efforts to
3
3
1
3
1
‡
2
and
representative examples, by H NMR experiments. H and 13C
NMR spectra of and in CDCl3 clearly showed a single set of
3 were investigated, as
1
1
convert 19 to its oxidized form 4, failed, under a variety of
oxidation conditions (PIFA/CAN/Oxone/mCPBA, etc) owing to
2
3
the formation of intractable mixture of products. Compound
well-resolved signals suggesting the effectiveness of our design
19 may assume DADD-type H-bonding code and not AADD
-
strategy (Fig. 3, vide infra).
2 | J. Name., 2012, 00, 1-3
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were investigated by H NMR
The significant downfield shift of NHs of
2
(11.86, 10.00
The dimerization of
2
and
3
ppm) and
intermolecular hydrogen bonding interactions involving the When a CDCl3 solution of
urea NH protons. Furthermore, the far downfield shift of NH to 10 µM, no detectable changes were observed in the
signals of and at 15.14 and 13.97 ppm, respectively, clearly chemical shift values of all the NH protons. This showed that
suggested the strong involvement of intramolecular bifurcated dimerization of
3
(11.87, 10.03 ppm), were indicative of strong dilution experiments (ESI,
‡
Fig. S23 and S24 respectively).
2
and were diluted from 100 mM
3
2
3
2
and
3
persisted at a lower concentration in
H-bonding (involving two acceptors).
CDCl3 with high Kdim value.
(b)
(a)
NH1
NH2
NH3
NH1
NH2
NH3
14
13
12
11
10
9
8
7
ppm
16
15
14
13
12
11
10
9
8
7
ppm
(d)
(c)
160
140
120
100
80
60
40
20
160
140
120
100
80
60
40
20 ppm
ppm
Fig. 3. 1H excerpts [(a), (b) (500 MHz)] and 13C [(c), (d) (125 MHz) spectra of
2 and 3, respectively, in CDCl3 showing single set of well-resolved signals.
Conservatively assuming more than 95% dimer formation at analysis11 of the chemical shift gave the dimerization constant
the lowest concentration studied (10 µM), the Kdim of Kdim value of 5.08 x 10 M-1 for and 2.57 x 10 M-1 for
in 20%
2
3
compounds 2 and 3 were estimated to be at a lower limit of DMSO-d6/CDCl3, respectively.
1.9 x 107 M-1 in CDCl3.
The dimerization of
Variable temperature 1H NMR studies (ranging from 223-
2
and
3
in various DMSO-d6/CDCl3 323K) further provided additional evidence for the stability of
mixtures were studied in order to further support self- molecular duplexes. Signals of NH2 (-1.00 ppb/K for
assembly by increasing the polarity of the solvent. The Kdim ppb/K for and -0.66 ppb/K for 18) and NH3 (-2.10 ppb/K for
values of and were determined quantitatively in the , -2.10 ppb/K for and -2.20 ppb/K for 18) showed
2, -0.60
3
2
·
2
3·
3
2
3
range from 5% to 20% DMSO-d6/CDCl3 (v/v) mixtures by 1H temperature coefficients suggestive of their strong
NMR dilution experiments. In 5% and 10% DMSO-d6/CDCl3 involvement in intermolecular hydrogen bonds when
mixtures, we observed negligible chemical shift changes of compared to NH1 which is involved in intramolecular S(6)-type
urea protons. Therefore, Kdim values were estimated to be at a hydrogen bonds (-0.20 ppb/K for
lower limit of 105 M-1 for
2, -1.40 ppb/K for 3 and -1.10
2
and 3 under this condition. These ppb/K for 18). These values also indicate the high stability of
findings proved that the duplexes are quite stable in mixture of the molecular duplexes (ESI,
solvents even though DMSO is a strongly competitive solvent
‡
Fig. S1, S3 and S5 respectively).
for hydrogen bonded complexes. Nonlinear regression
NH2
NH2
NH1
(a)
(b)
ppm
ppm
ppm
9.6
3.6
3.8
4.0
10.0
10.2
NH3
NH3
10.0
10.4
10.8
ppm
C20H
NH2/NH3
NH2/NH3
NH1/C20H
4.2
14.2 14.0 13.8
ppm
12.0 11.8
ppm
12.0
11.5
C9H
C5H
C2H
NH1
C5H
ppm
9.1
ppm
ppm
8.0
ppm
C5H/C21H
6.2
3.8
4.0
4.2
C21H
C7H
C2H
C8H
C20H
6.4
C9H/C7H
8.4
C5H/C8H
NH1/C2H
C2H/C20H
7.0
9.2
6.6
7.2 7.1 7.0
ppm
15.315.215.1
ppm
7.0
6.5
ppm
7.2
7.1
ppm
Fig. 4. Characteristic NOE excerpts of homodimer of 2 (a) and 3 (b) (CDCl3, 400 MHz, 298 K). Note: EH = 2-ethylhexyl
The self-assembling system
3 exhibited fluorescence, fluorescent, the duplex stability of 3·3 was also investigated by
owing to the presence of the hydroquinone moiety.8 Being fluorescence spectroscopic methods, in addition to NMR
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2
(a) Y. Hisamatsu, S. Banerjee, M. Avinash, T. Govindaraju and
C. Schmuck, Angew. Chem. Int. Ed., 2013, 52, 12550; (b) M.
Pichlmaier, R. F. Winter, M. Zabel, S. Zalis, J. Am. Chem. Soc.,
2009, 131, 4892; (c) A. M. Kushner, V. Gabuchian, E. G.
Johnson and Z. Guan, J. Am. Chem. Soc., 2007, 129, 14110;
(d) P. Y. W. Dankers, M. C. Harmsen, L. A. Brouwer, M. J. Van
Luyn and E. W. Meijer, Nat. Mater., 2005, 4, 568; (e) M.
Ikeda, T. Nobori, M. Schmutz and J.-M. Lehn, Chem. Eur. J.,
2005, 11, 662.
(a) F. H. Beijer, R. P. Sijbesma, H. Kooijman, A. L. Spek and E.
W. Meijer, J. Am. Chem. Soc., 1998, 120, 6761; (b) S. H. M.
Söntjens, R. P. Sijbesma, M. H. P. van Genderen and E. W.
Meijer, J. Am. Chem. Soc., 2000, 122, 7487.
(a) A. Micoli, M. Nieuwenhuizen, M. Koenigs, M. Quintana, R.
Sijbesma and M. Prato, Chem. Eur. J., 2015, 21, 14179; (b) S.
Wang, H. Guo, X. Wang, Q. Wang, J. Li and X. Wang,
Langmuir, 2014, 30, 12923; (c) J.-S. Chen, P.-W. Zhou, G.-Y.
Li, T.-S. Chu and G.-Z. He, J. Phys. Chem. B, 2013, 117, 5212;
(d) L. Shi, X. Wang, C. A. Sandoval, M. Li, Q. Qi, Z. Li and K.
Ding, Angew. Chem. Int. Ed., 2006, 45, 4108; (e) O. A.
Scherman, G. Ligthart, H. Ohkawa, R. P. Sijbesma and E. W.
Meijer, Proc. Natl. Acad. Sci. U.S.A., 2006, 103, 11850; (f) H.
methods (vide supra). The dimerization constant of
3 was
determined by using a fluorescence spectroscopic method, as
reported previously by the Meijer group.3b Concentration-
dependent changes in the intensities of 3 at 400 nm appeared
in the range of 10-9 M to 10-6 M in chloroform. Nonlinear
regression analysis11a of the fluorescence data gave
a
dimerization constant Kdim value of (2.02 ± 2.42) x 108 M-1 for
3
(ESI,‡ Fig. S31 and S32).
Despite several efforts, compounds
3
4
1,
2
and
3
were highly
resistant to crystal formation. Therefore, their duplex
formation was further investigated via solution-state NMR and
HRMS-ESI studies. Two-dimensional NOESY NMR studies in
CDCl3 provided the most diagnostic evidence for the formation
of homodimer structures of
characteristic NOE correlation between NH2 and NH3 proton
of in CDCl3 suggested a linear arrangement. The NOEs
between C9H and C7H and NH1 and C2H in confirmed the
AADD-type self-complementary dimer formation (Fig. 4a, vide
supra). The compound exhibited similar characteristic NOEs
2 and 3 in solution. The
2
2
3
Sun, J. Steeb and A. E. Kaifer, J. Am. Chem. Soc., 2006, 128
,
(NH2/NH3, NH1/C20H, C5H/C8H, C5H/C21H and C2H/C20H;
2820; (g) L. Sánchez, N. Martín and D. M. Guldi, Angew.
Chem. Int. Ed., 2005, 44, 5374; (h) M. T. Rispens, L. Sanchez,
J. Knol and J. C. Hummelen, Chem. Commun., 2001, 161; (i) J.
J. Gonzalez, S. Gonzalez, E. M. Priego, C. Luo, D. M. Guldi, J.
de Mendoza and N. Martin, Chem. Commun., 2001, 163.
P. S. Corbin and S. C. Zimmerman, J. Am. Chem. Soc., 1998,
120, 9710.
(a) B. P. Mudraboyina and J. A. Wisner, Chem. Eur. J., 2012,
18, 14157; (b) X. Li, Y. Fang, P. Deng, J. Hu, T. Li, W. Feng and
L. Yuan, Org. Lett., 2011, 13, 4628; (c) W.-J. Chu, Y. Yang and
C.-F. Chen, Org. Lett., 2010, 12, 3156; (d) J. S. Nowick, Acc.
Chem. Res., 2008, 41, 1319; (e) J. Zhu, J.-B. Lin, Y.-X. Xu, X.-B.
Fig. 4b, vide supra). In addition, HRMS-ESI mass spectra
showed molecular ion peaks (787.4402 for [
787.4393) and (805.4607 for [
+ H]+, calcd 805.4587),
2·2
+ H]+, calcd
3·3
corresponding to the presence of the duplex (ESI,
and S31 respectively).
‡ page S23
5
6
In summary, the tricky issue of prototropy in heterocycle-
based AADD-type self-assembling systems was effectively
solved by an effective method of freezing their hydrogen
bonding codes, by using intramolecular bifurcated hydrogen
bonding interactions. It is noteworthy that this elegant
strategy may also find application elsewhere, wherein proton
Shao, X.-K. Jiang and Z.-T. Li, J. Am. Chem. Soc., 2006, 128
,
12307; (f) V. G. H. Lafitte, A. E. Aliev, P. N. Horton, M. B.
Hursthouse, K. Bala, P. Golding and H. C. Hailes, J. Am. Chem.
Soc. 2006, 128, 6544; (g) Y. Yan, H. Zeng and B. Gong, J. Am.
Chem. Soc., 1999, 121, 5607.
S. Kheria, S. Rayavarapu, A. S. Kotmale, R. G. Gonnade and G.
J. Sanjayan, Chem. Eur. J., 2017, 23, 783.
Hydroquinone-conjugated systems often show fluorescence;
see: (a) B. Gui, X. Meng, Y. Chen, J. Tian, G. Liu, C. Shen, M.
Zeller, D. Yuan and C. Wang, Chem. Mater., 2015, 27, 6426;
(b) V. K. Praveen, C. Ranjith, E. Bandini, A. Ajayghosh and N.
Armaroli, Chem. Soc. Rev., 2014, 43, 4222; (c) P. Jonkheijm,
N. Stutzmann, Z. Chen, D. M. de Leeuw, F. Wurthner, E. W.
Meijer and A. P. H. J. Schenning, J. Am. Chem. Soc., 2006,
128, 9535.
shift-mediated structural changes become
a detrimental
factor. Based on the results obtained from extensive NMR
studies, we could unambiguously confirm that the modified
ureidopyrimidone-based AADD-type self-complementary
quadruple hydrogen-bonded systems show high Kdim value
(Kdim > 107 M-1 in CDCl3), without competition from undesired
tautomers. Advantageously, using this strategy, we could also
7
8
design
a novel AADD-type quadruple H-bonding system
endowed with a built-in fluorophore, which could augment its
application potential in supramolecular chemistry.
S.K, S.R and A.S.K are thankful to CSIR, New Delhi for
research fellowships. GJS thanks the SSB-000726 project for
financial support.
9
I. V. Boldyrev, I. F. Vladimirtsev, E. A. Romanenko, N. G.
Korzhenevskaya, E. V. Titov and V. M. Cherkasov, Chem.
Heterocycl. Compd., 1977, 13, 1006.
10 (a) T. Yakura, Y. Yamauchi, Y. Tian and M. Omoto, Chem.
Pharm. Bull. 2008, 56, 1632; (b) K. I. Shivakumar and G. J.
Sanjayan, Synthesis, 2013, 45, 896.
11 (a) C. S. Wilcox, Frontiers in supramolecular organic
chemistry and photochemistry, H.-J. Schneider and H. Dürr,
VCH, New York, 1991, pp 123; (b) K. A. Connors, Binding
constants: the measurement of molecular complex stability,
Wiley-Interscience, New York 1987.
Notes and references
1
(a) L. Yang, X. Tan, Z. Wang and X. Zhang, Chem. Rev., 2015,
115, 7196; (b) T. Aida, E. W. Meijer and S. I. Stupp, Science,
2012, 335, 813; (c) J. D. Fox and S. J. Rowan,
Macromolecules, 2009, 42, 6823; (d) M. Fathalla, C. M.
Lawrence, N. Zhang, J. L. Sessler and J. Jayawickramarajah,
Chem. Soc. Rev., 2009, 38, 1608; (e) J.-M. Lehn, Chem. Soc.
Rev., 2007, 36, 151; (f) A. J. Wilson, Soft Matter, 2007, 3, 409;
(g) P. Y. W. Dankers and E. W. Meijer, Bull. Chem. Soc. Jpn.,
2007, 80, 2047; (h) L. J. Prins, D. N. Reinhoudt and P.
Timmerman, Angew. Chem. Int. Ed., 2001, 40, 2382; (i) C.
Schmuck and W. Wienand, Angew. Chem. Int. Ed., 2001, 40
4363.
,
4 | J. Name., 2012, 00, 1-3
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