A 3D chiral hydrogen bond framework based on phenanthrolinium hydrogen 4,5-dichlorophthalate: Crystal structure and luminescent properties

Article abstract of DOI:10.1515/znb-2012-0114

A salt with the composition [C₁₂H₉N ₂][C₈H₃Cl₂O₄] (1) with 4,5-dichlorophthalic acid and 1,10-phenanthroline (phen) has been synthesized and characterized by IR, UV spectroscopy,

Full text of DOI:10.1515/znb-2012-0114

A 3D Chiral Hydrogen Bond Framework Based on Phenanthrolinium
Hydrogen 4,5-Dichlorophthalate: Crystal Structure and Luminescent
Properties
Bing An, Yan Bai, and Fan Yang
Institute of Molecular and Crystal Engineering, College of Chemistry and Chemical Engineering,
Henan University, Kaifeng 475004, P. R. China
Reprint requests to Prof. Yan Bai. Fax: +86-378-3881589. E-mail: baiyan@henu.edu.cn
Z. Naturforsch. 2012, 67b, 85 – 88; received November 12, 2011
A salt with the composition [C12H9N2][C8H3Cl2O4] (1) with 4,5-dichlorophthalic acid and 1,10-
phenanthroline (phen) has been synthesized and characterized by IR, UV spectroscopy, elemental
analysis, and X-ray crystallography. Compound 1 represents a 3D chiral supramolecular frame-
work containing monohelical chains (21 axis) through multiform C–H···O, O–H···O, N–H···N in-
tramolecular hydrogen bonds and C–H···O, N–H···O intermolecular hydrogen bonds. Otherwise,
two types of face-to-face π ···π interactions between the aromatic rings are found in the solid state.
The luminescent properties of compound 1 were investigated in the solid state at room temperature.
Key words: Hydrogen Bond, Crystalline Salt, Helix, Luminescence Properties
Introduction
zation of simple achiral synthons without any chiral
auxiliaries [6, 14]. As a part of our continuing investi-
gations on functional supramolecular systems and their
photoluminescent properties [4, 13, 15], in the present
paper a chiral crystalline salt [C12H9N2][C8H3Cl2O4]
(1) was synthesized and characterized by single-crystal
X-ray diffraction (Scheme 1). Compound 1 exhibits
strong fluorescent emission in the solid state at r. t.
Supramolecular crystalline salts have attracted sig-
nificant interest due to their potential applications in
fields as diverse as chemistry, biology and materials
science [1 – 4]. Hydrogen bonds and π ···π interac-
tions in synthons represent two important classes of in-
termolecular forces, with which many excellent struc-
tures have been reported to demonstrate how the ratio-
nal design and assembly of supramolecular solids can
be achieved [5 – 7]. These materials are attractive to
chemists not only for the variety of topologies and in-
triguing frameworks, but also for their interesting cat-
alytic, electric and optical properties [8 – 10].
Experimental Section
General
Materials: All chemicals were reagent grade quality ob-
tained from commercial sources and used without further pu-
rification.
Instrumentation: Elemental analyses (C, H and N) were
carried out on a Perkin-Elmer 240C analytical instrument.
IR spectra were recorded from KBr pellets with a Nicolet
170 SXFT-IR spectrophotometer in the 4000 – 400 cm−1 re-
gion. The UV/Vis spectra were measured in methanol solu-
tion with a Hitachi U-4100 spectrophotometer, and the lumi-
nescence spectra were obtained on a Hitachi F-7000 fluores-
cence spectrophotometer.
Scheme 1. Chemical formula drawing of compound 1.
Organic carboxylic acids and nitrogen-containing
organic molecules as hydrogen-bonded synthons find
broad use to form complicated structures in the field
of crystal engineering [11 – 13]. The design and con-
struction of a chiral framework sustained by hydro-
gen bonds represents a considerable synthetic chal-
lenge since this has to be achieved via spatial organi-
Synthesis
Compound 1 was synthesized by a hydrothermal method.
A mixture of 4,5-dichlorophthalic acid (0.037 g, 0.15 mmol),
1,10-phenanthroline (0.027 g, 0.15 mmol) and NaOH
(0.008 g, 0.2 mmol) in 3 mL of MeOH and 5 mL of water
c
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B. An et al. · Phenanthrolinium Hydrogen 4,5-Dichlorophthalate
Table 1. Summary of crystal data and refinement results for
the title compound.
suite [16]. All non-hydrogen atoms were refined anisotropi-
cally by full-matrix least-squares techniques, and all hydro-
gen atoms were geometrically fixed to allow riding on the
parent atoms to which they are attached. Space group, lattice
parameters and other relevant information are listed in Ta-
ble 1. Relevant interatomic bond lengths and angles for 1 are
given in Table 2.
CCDC 843320 contains the supplementary crystallo-
graphic data. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data request/cif.
Formula
Mr
C20H12Cl2N2O4
415.22
0.18×0.16×0.15
monoclinic
P21
6.4232(13)
7.5415(16)
18.347(4)
94.698(3)
885.8(3)
Crystal size, mm3
Crystal system
Space group
˚
a, A
˚
b, A
˚
c, A
β, deg
3
˚
V, A
Z
2
1.56
4.0
2.70 – 28.27
424
Dcalcd, g cm−3
µ(MoKα ), cm−1
θ range for data collection, deg
F(000), e
Results and Discussion
IR and UV spectra
hkl range
−7 ≤ h ≤ 2, −9 ≤ k ≤ 9,
−21 ≤ l ≤ 20
3592 / 2910 / 0.011
253
0.0308 / 0.0789
0.0337 / 0.0811
0.06(6)
In the IR spectrum of compound 1, two strong broad
bands at 3440 and 3077 cm−1 are assigned to the
ν(OH) and ν(NH) stretching vibrations, which agrees
well with those of the relevant components [17, 18].
Compound 1 shows several bands at 1695, 1599
and 1575 cm−1 which can be attributed to the ν(OCO)
stretching vibrations of the carboxyl units. Their iden-
tity was finally confirmed by X-ray crystallography.
The UV spectrum of compound 1 in methanol solution
displays a strong absorption peak at 268 nm, which can
be assigned to the n-π∗ transition.
Refl. measured / unique / Rint
Param. refined
R1(F) / wR2(F2) [I ≥ 2σ(I)]
R1(F) / wR2(F2) (all refl.)
x (Flack)
Gof (F2)
1.033
0.15 / −0.20
−3
˚
∆ρfin (max / min), e A
˚
Table 2. Selected bond lengths (A) and angles (deg) of the
title compound.
O(1)–C(13)
O(3)–C(14)
C(13)–C(15)
C(15)–C(20)
C(16)–C(17)
O(1)–C(13)–O(2) 121.6(2)
O(2)–C(13)–C(15) 119.63(18) O(3)–C(14)–C(16) 119.43(18)
O(4)–C(14)–C(16) 117.3(2) C(20)–C(15)–C(13) 112.76(18)
C(20)–C(15)–C(16) 117.96(19) C(17)–C(16)–C(15) 118.34(19)
C(16)–C(15)–C(13) 129.26(18) C(15)–C(16)–C(14) 128.18(18)
C(17)–C(16)–C(14) 113.46(18)
1.215(3)
1.273(3)
1.524(3)
1.393(3)
1.381(3)
O(2)–C(13)
O(4)–C(14)
C(14)–C(16)
C(15)–C(16)
1.283(3)
1.227(3)
1.526(3)
1.413(3)
Crystal and molecular structure
The structure analysis by single-crystal X-ray
diffraction revealed that compound 1 forms a 3D chi-
ral supramolecular framework which contains heli-
cal chains on a 21 axis. The asymmetric unit con-
sists of a 4,5-dichlorophthalic acid monoanion and a
phenanthrolinium mono cation. As shown in Fig. 1,
one hydrogen atom of an O(4) atom in a carboxyl
O(4)–C(14)–O(3) 123.2(2)
was stirred for 0.5 h, sealed in a 30 mL Teflon-lined stainless-
steel bomb and heated at 160 ◦C for 96 h. Then the autoclave
was cooled to r. t., and colorless block shaped crystals were
isolated and washed with distilled water. Yield: 21 %. – Ele-
mental analysis for C20H12Cl2N2O4: calcd. C 57.85, H 2.91,
N 6.75; found C 57.78, H 2.95, N 6.85.
X-Ray crystallographic study
A suitable single crystal of size 0.18 × 0.16 × 0.15 mm3
as obtained above was selected for the crystallographic study
and mounted on a Bruker SMART APEX CCD diffractome-
ter with ω and φ scan mode. All diffraction measurements
were performed at room temperature using graphite-mono-
˚
chromatized MoKα radiation (λ = 0.71073 A). The struc-
Fig. 1. ORTEP drawing of compound 1 with atom numbering
scheme adopted. Hydrogen bonds are shown as dashed lines;
displacement ellipsoids at the 50 % probability level.
ture was solved by Direct Methods and refined by full-
matrix least-squares on F2 using the SHELXS/L 97 program
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B. An et al. · Phenanthrolinium Hydrogen 4,5-Dichlorophthalate
87
Table 3. Hydrogen bonding in-
D–H···A
d(D–H) d(H···A) d(D···A) ∠ (D–H···A) Symmetry transformation
˚
teractions (A, deg) in 1.
for A
N(1)–H(2A)···O(4)
N(2)–H(2A)···N(1)
O(2)–H(2C)···O(3)
C(8)–H(8A)···O(3)
C(9)–H(9A)···O(1)
C(10)–H(10A)··· O(3)
0.86
0.86
0.82
0.93
0.93
0.93
1.88
2.40
1.58
2.52
2.47
2.53
2.697(2)
2.737(3)
2.395(3)
3.298(3)
3.392(3)
3.300(3)
159
104
178
141
169
141
1−x, −1/2+y, 1−z
−x, 1/2+y, 1−z
group of 4,5-dichlorophthalic acid is transfered to an
N(2) atom of phenanthroline (phen). The typical char-
acter of the structure of compound 1 is the existence
of multiple strong intramolecular hydrogen bonds in
each component and intermolecular hydrogen bonds
between 4,5-dichlorophthalate anion and protonated
phen (Table 3). An intramolecular hydrogen bond
O(2)–H(2C)···O(3) is found in the acid component
(Fig. 1). As for O(2)–H(2C)···O(3), the distance of
˚
O(2)···O(3) is 2.395(3) A, suggesting a strong hydro-
gen bond with the angle O(2)–H(2C)···O(3) of 178◦.
An N(2)–H(2A)···N(1) intramolecular hydrogen bond
is found in the protonated cation with an N(2)···N(1)
˚
distance of 2.737(3) A and an N(2)–2(2A)···N(1)
angle of 104◦. Moreover, there is a pair of in-
termolecular hydrogen bonds, C(10)–10(10A)···O(3)
and N(2)–2(2A)···O(4), between the protonated nitro-
gen atom N(2) and one carbon atom C(10) in the cation
and two carboxylate oxygen atoms O(3), O(4) of the
4,5-dichlorophthalic acetate to closely link cation and
anion.
Fig. 2 (color online). Supramolecular structure of com-
pound 1 showing 21 helical chains around the yellow axes
and hydrogen bonds (dashed line); π ···π interactions are be-
tween rings drawn with increased thickness.
The chiral assembly from achiral components on the
basis of helical motifs is of current interest as one of
the most attractive and evocative strategies due to the
intrinsic chiral character of helicates [19 – 21]. Herein,
single-crystal structure analysis shows that (achiral) 1
crystallizes in the chiral monoclinic space group P21 as
conglomerate. The single crystals are enantiomerically
pure, the one chosen exhibits M helicity by a sponta-
neous resolution process. Fig. 2 shows the chiral infi-
nite monohelical chains around the 21 axis at (−1/2,
y, 1/2) constructed by intrachain C(8)–8(8A)···O(3)
(1−x, −1/2+y, 1−z) hydrogen bonds between adja-
cent units in the dimeric structures. The helical pitch
˚
is 7.5415(16) A along the crystallographic b axis,
Fig. 3. The emission spectrum (λex = 280 nm) of compound 1
in the solid state at r. t.
which results in one full rotation around the 21 helical
axis. Furthermore, adjacent 21 helical chains are linked
by interchain hydrogen bonds C(9)–9(9A)···O(1) (−x, lical chains are found in the solid state, and proba-
1/2 + y, 1 − z) to construct a multi-helical array. Ad- bly play an important role in stabilizing the frame-
ditionally, two kinds of face-to-face π···π interac- work. The π···π interaction between the aromatic
tions involving two parallel rings from adjacent he- rings [C(15)–15(20)] and [N(1)C(1)–1(4)C(12)] is
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B. An et al. · Phenanthrolinium Hydrogen 4,5-Dichlorophthalate
characterized by centroid-centroid separations of 3.80 main luminescent emission peak at 387 nm and a
˚
and 3.76 A, and the shortest interplanar atom···atom shoulder emission at 420 nm. Compared to that of 4,5-
˚
distances are 3.44 and 3.51 A, respectively. Studies dichlorophthalic acid and phen by literature [23, 24],
on crystal engineering reveal that these kinds of inter- the photophysical properties of compound 1 may be
molecular force are important in molecular structure attributed to the π-π∗ and n-π∗ transitions on the basis
and molecular packing [22]. Herein, the above shown of the emission of acid and phen. The observed varia-
multiform intermolecular interactions are substantially tion in the luminescent is perhaps due to the presence
strong, and the chiralities of helical units are extended of multiform strong hydrogen bond interactions in the
into 3D supramolecular frameworks to construct a chi- supramolecular crystal structure of 1.
ral species.
Acknowledgement
Luminescence properties
This work was supported by the Education Department
of Henan Province and the Foundation co-established by the
Province and the Ministry of Henan University.
The solid-state luminescent properties of com-
pound 1 were investigated at r. t. As shown in Fig. 3,
upon excitation at 280 nm, compound 1 shows the
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