13
C
4
.52 (s, 2H, two aromatic CH), 4.77 (s, 2H, two aromatic CH);
In conclusion, we have reported the synthesis and crystal
structure of an adenine–ferrocene conjugate, the nucleobase
forms a ribbon-like motif with the help of intermolecular
hydrogen bonds and these ribbons are further connected by
CHꢀ ꢀ ꢀO hydrogen bonding, thus forming a network of ade-
nine ribbons. Hydrogen bonding, p–p stacking and CH–p
interactions play an important role in the stability of the
homoadenine tetrad structure, which enables ferrocenyl moi-
eties to adopt an interesting spatio-temporal arrangement in
the lattice superstructure.
3
NMR (100 MHz, CDCl , 25 1C, TMS): d (ppm) 25.98, 42.29, 69.19,
6
9.88, 72.52, 78.23, 200.55.
Synthesis of 3-(6-amino-9H-purin-9-yl)-1-ferrocenylpropan-1-one (1):
To a solution of adenine (0.5 g, 1.0 mol) in 20 ml of dry DMF was
added K CO (0.61 g, 1.2 mol) and B (1.18 g, 0.99 mol) and the
2
3
reaction mixture was stirred for 24 h at room temperature under a
nitrogen atmosphere. The solvent was then removed under reduced
pressure and the residue was purified by column chromatography over
neutral alumina (chloroform/methanol, 95 : 5), affording 0.35 g.
(
+
25.48%) of 1 as red color solid. HRMS: (M+1) calculated:
1
3
(
76.0861, found: 376.0829; Decomposes above 190 1C; H NMR
500 MHz, DMSO-d , 25 1C, TMS): d (ppm) 3.39 (s, 2H, CH2),
3.95 (s, 5H, Cp ring), 4.46 (s, 2H, CH2), 4.54 (s, 2H, Cp ring), 4.77 (s,
H, Cp ring), 7.19 (s, 2H, NH2), 8.13 (s, 1H, C8-H), 8.17 (s, 1H, C2-
6
, 25 1C, TMS): d (ppm) 37.96,
8.32, 68.89, 69.27, 72.21, 78.41, 141.24, 152.20, 155.86, 200.58.
6
We thank the Single Crystal CCD X-ray facility at IIT-
Kanpur; CSIR, for S. P. Mukherjee Fellowship (J.K.). This work
is supported by Bioinorganic Chemistry Initiative, DST, India.
2
13
H); C NMR (100 MHz, DMSO-d
3
Notes and references
1 (a) S. I. Kirin, Heinz-Bernhard Kraatz and N. Metzler-Nolte,
Chem. Soc. Rev., 2006, 35, 348; (b) D. R. van Staveren and N.
Metzler-Nolte, Chem. Rev., 2004, 104, 5931.
z General: All reactions were performed under nitrogen atmosphere
by using standard Schlenk techniques, while the workup was per-
formed in the air. All solvents were distilled following standard
procedures prior to use. 3-Bromopropanoic acid and adenine were
purchased from Sigma-Aldrich, Mumbai, India, whereas anhydrous
aluminium chloride, thionyl chloride, and ferrocene were purchased
2 (a) T. Moriuchi and T. Hirao, Top. Organomet. Chem., 2006, 17,
143; (b) M. Salmain, ‘‘Labeling of proteins with organometallic
complexes: Strategies and applications’’ in Bioorganometallics, ed.
G. Jaouen, Wiley-VCH Verlag, Weinheim, Germany, 2006, pp
181–213; (c) A. Maurer, Heinz-Bernhard Kraatz and N. Metzler-
Nolte, Eur. J. Inorg. Chem., 2005, 16, 3207; (d) D. R. van Staveren,
T. Weyhermueller and N. Metzler-Nolte, Dalton Trans., 2003, 2,
210; (e) H. S. Mandal and Heinz-Bernhard Kraatz, J. Organomet.
Chem., 2003, 674, 32.
3 (a) A. N. Patwa, S. Gupta, R. G. Gonnade, V. A. Kumar, M. M.
Bhadbhade and K. N. Ganesh, J. Org. Chem., 2008, 73, 1508; (b)
E. Freisinger and R. K. O. Sigel, Coord. Chem. Rev., 2007, 251,
1834; (c) B. Lippert, Prog. Inorg. Chem., 2005, 54, 385; (d) J. L.
Sessler and J. Jayawickramarajah, Chem. Commun., 2005, 15,
1939; (e) S. Sivakova and S. J. Rowan, Chem. Soc. Rev., 2005,
34, 9; (f) A. Houlton, Adv. Inorg. Chem., 2002, 53, 87; (g) A. R.
Pike, L. C. Ryder, B. R. Horrocks, W. Clegg, B. A. Connolly and
A. Houlton, Chem.–Eur. J., 2004, 11, 344, and references cited
therein.
1
13
from Spectrochem, Mumbai, India, and used as supplied. H and
NMR spectra were recorded on JEOL-JNM LAMBDA 400 model
C
1
operating at 400 and 100 MHz, respectively. H and NOE spectra of 1
were recorded on JEOL ECX-500 model operating at 500 MHz.
HRMS mass spectra were recorded at IIT Kanpur, India, on Waters
Q-Tof Premier Micromass HAB 213 mass spectrometer using capillary
voltage 2.6–3.2 kV.
Synthesis of 3-bromopropanoyl chloride (A): 10 ml thionyl chloride
was added to 5 g of 3-bromopropanoic acid at room temperature then
the reaction mixture was refluxed for eight hours under nitrogen
atmosphere. The solvent was evaporated under reduced pressure and
A was obtained as a light yellow viscous liquid (4.5 g, yield 80%) which
was used in the next step without further characterization. The
synthetic scheme of conjugate 1 is given in Scheme 1.
Synthesis of 3-bromo-1-ferrocenylpropan-1-one (B): To a solution of
ferrocene (4.0 g, 1.0 mol) in dichloromethane (50 ml), A was added
4 (a) C. S. Purohit, A. K. Mishra and S. Verma, Inorg. Chem., 2007,
46, 8493; (b) C. S. Purohit and S. Verma, J. Am. Chem. Soc., 2007,
129, 3488; (c) C. S. Purohit and S. Verma, J. Am. Chem. Soc., 2006,
128, 400; (d) C. Madhavaiah and S. Verma, Chem. Commun., 2003,
800; (e) S. G. Srivatsan, M. Parvez and S. Verma, J. Inorg.
Biochem., 2003, 97, 340; (f) S. G. Srivatsan, M. Parvez and S.
Verma, Chem. Eur. J., 2002, 8, 5184; (g) S. G. Srivatsan and S.
Verma, Chem.–Eur. J., 2001, 7, 828; (h) S. G. Srivatsan and S.
Verma, Chem. Commun., 2000, 515.
5 (a) J. P. Garcia-Teran, O. Castillo, A. Luque, U. Garcia-Couceiro,
G. Beobide and P. Roman, Inorg. Chem., 2007, 46, 3593; (b) D.
Dobrzynska and L. B. Jerzykiewicz, J. Am. Chem. Soc., 2004, 126,
11118.
6 (a) G. R. Desiraju, Chem. Commun., 2005, 2995; (b) M. Nishio,
CrystEngComm, 2004, 130; (c) E. A. Meyer, R. K. Castellano and
F. Diederich, Angew. Chem., Int. Ed., 2003, 42, 1210; (d) T. Steiner,
Angew. Chem., Int. Ed., 2002, 41, 48; (e) M. Nishio, Y. Umezawa,
M. Hirota and Y. Takeuchi, Tetrahedron, 1995, 51, 8665.
7 A. Gil, V. Branchadell, J. Bertran and A. Oliva, J. Phys. Chem. B,
2007, 111, 9372.
8 H. Suezawa, T. Hashimoto, K. Tsuchinaga, T. Yoshida, T. Yuzuri,
K. Sakakibara, M. Hirota and M. Nishio, J. Chem. Soc., Perkin
Trans. 2, 2000, 1243.
(3.69 g, 1.0 mol) slowly at 0 1C under nitrogen atmosphere. After this,
aluminium chloride (3.01 g, 1.05 mol) was added in small portions at
such a rate that the reaction mixture remains below 5 1C. The
appearance of a deep blue colour indicates that the reaction was
occurring. This addition requires about 20 min, and after its comple-
tion stirring was continued for 30 in an ice-water bath and then at
room temperature for 2 h. After this time the reaction mixture was
cooled again in an ice bath and 50 ml of chilled water was added
cautiously which resulted in a two-phase mixture. This was then
vigorously stirred for 30 min. This mixture was then transfered into
a separating funnel and the organic layer was collected. The aqueous
layer was extracted twice more with 20 ml portions of dichloro-
methane. The combined dichloromethane solutions were washed twice
with 50 ml portions of 10% aqueous sodium hydroxide and dried over
sodium sulfate. It was then evaporated at reduced pressure and
column chromatographed over neutral alumina (petroleum ether/
chloroform, 85 : 15), yielding 3.53 g. (51%) of B as a viscous, reddish
calculated:
+
liquid, which gradually solidifies. HRMS: (M+1)
3
1
20.9577, found: 320.9563; M.P. = 66 1C; H NMR (400 MHz,
3
CDCl , 25 1C, TMS): d (ppm) 3.28 (t, J = 6.60 and 6.56 Hz, 2H,
2 2
CH ), 3.71 (t, J = 6.60 and 6.56 Hz, 2H, CH ), 4.23 (s, 5H, Cp ring),
2
528 | Chem. Commun., 2008, 2526–2528
This journal is ꢁc The Royal Society of Chemistry 2008