448
J Incl Phenom Macrocycl Chem (2010) 68:447–452
change in emission of naphthalene. Upon complexation,
the monomer emission of naphthalene is decreased with
simultaneous growth of a diagnostic new peak at higher
wavelength. Dihydrogen phosphate is an important anion
and its recognition by different receptors are known in the
literature [8–11]. In the present communication, receptor 1,
which is simple and easy-to-make elegantly shows selec-
tive recognition of dihydrogen phosphate by exhibiting
new emission at longer wavelength due to hydrogen bond
mediated excimer formation.
mixture was allowed to stir at room temperature for 8 h. The
solvent was evaporated to dryness under vacuum. The resi-
due was dissolved in CHCl3 (30 mL), washed with water
(2 9 15 mL) and dried over anhydrous Na2SO4. Solvent
was distilled off and the crude was purified through column
chromatography using 35% ethyl acetate in petroleum ether
to give the expected product 1 as white solid (114 mg, 69%
yield) and mp was noted as 270–272 °C.
1H NMR (CDCl3, 400 MHz): d 7.99–7.91 (m, 5H), 7.92
(d, 1H, J = 8.4 MHz), 7.68–7.56 (m, 8H), 4.78 (d, 1H,
J = 9.7 Hz), 4.74 (d, 1H, J = 9.7 Hz), 4.66 (d, 1H,
J = 16.8 Hz), 4.62 (d, 1H, J = 16.8 Hz); 13C NMR
(CDCl3, 125 Hz): d d 164.49, 164.19, 137.3, 134.0, 129.1,
128.4, 126.9, 126.5, 126.0, 125.4, 122.9, 53.8; FTIR: m
cm-1 (in KBr) 3,443, 3,049, 2,918, 1,645, 1,597, 1,480,
1,332, 1,274; Mass (EI): 389.2 (M ? Na?), 367.2
(M ? H?).
Experimental
Compound 1,4-di(1-naphthyl)-2,5-piperazinedione 1 was
obtained according to the Scheme 1. Reaction of 1-naph-
thylamine with chloroacetyl chloride gave the compound 2,
which on refluxing in CH3CN in the presence of either
K2CO3 or Cs2CO3 afforded the piperazine derivative 1 in
appreciable yield.
Results and discussion
2-Chloro-N-(naphthalen-1-yl)acetamide (2)
Compound 1 was crystallized from CHCl3 containing one
drop of DMSO. Single crystal structure analysis revealed
the inclusion of water in the lattice and gave the same
structural information as observed previously by other [5].
Figure 1 shows the ORTEP plot of 1 where one molecule
of water is present as crystal hydrate. In 1, two naphtha-
lenes are not in the plane of diketopiperazine ring. They are
perpendicularly disposed around the planar DKP ring. The
inclusion water connects the diketopiperazine units through
hydrogen bonding and forms water templated hydrogen
bonded polymeric chain (see supporting data). It is worth
noting that the polarised C–H bonds adjacent to amide
carbonyl carbons of piperazine ring are cooperatively
involved in the formation of hydrogen bonds with water. In
addition, the carbonyl oxygen of piperazine ring of one
chain is connected with the C–H bond of piperazine ring of
adjacent chain, thereby giving a bilayer hydrogen bonded
network (Fig. 2). In the network, there is face-to-face and
edge-to-face p-stacking interactions between the two
In dry CH2Cl2 (20 mL) 1-aminonaphthalene (250 mg,
1.75 mmol) was dissolved. To it, 2-chloroacetyl chloride
(0.15 mL, 1.92 mmol) in 10 mL dry CH2Cl2 was added
dropwise followed by measured amount of Et3N. Reaction
mixture was stirred at room temperature for 10 h. Solvent
was evaporated, washed with saturated NaHCO3 solution
and extracted with CHCl3 (3 9 20 mL). The organic layer
was dried over anhydrous Na2SO4, concentrated and
purified through column chromatography using 7% ethyl
acetate in petroleum ether. Compound 2 was obtained as
white solid (335 mg, 87% yield). Mp was recorded as
163 °C.
1H NMR (CDCl3, 400 MHz): d 8.79 (s, 1H), 8.02 (d,
1H, J = 7.6 Hz), 7.93–7.88 (m, 2H), 7.79 (d, 1H,
J = 8.4 Hz), 7.62–7.51 (m, 3H), 4.38 (s, 2H); FTIR: m
cm-1 (in KBr) 3,256, 3,052, 2,958, 2,854, 1,666, 1,557,
1,505, 1,398, 1,248.
´
˚
naphthalene rings having a separation of 3.71 and 3.65 A
1,4-di(Naphthalen-1-yl)piperazine-2,5-dione (1)
along the b-axis, respectively. The thermal stability of
water molecule in 1. H2O was studied by thermogravi-
metric analysis (TGA) (Fig. 3). The weight loss for water
was 4.99% that occurred in the region 89–152 °C. Looking
To a stirred solution of 2 (100 mg, 0.45 mmol) in CH3CN
(20 mL), K2CO3 (10 mg) was added and the reaction
Scheme 1 Synthesis of
compound 1
O
O
Cl
NH2
HN
N
N
O
ClCH2COCl
Et3N, Dry CH2Cl2
K2CO3, TBAI
Dry CH3CN
1
2
123