supplementary materials


bx2439 scheme

Acta Cryst. (2013). E69, o802-o803    [ doi:10.1107/S1600536813011185 ]

3,3'-({4-[(4,5-Dicyano-1H-imidazol-2-yl)diazenyl]phenyl}imino)dipropionic acid

R. Centore, V. Piccialli and A. Tuzi

Abstract top

The title compound, C17H15N7O4, is a push-pull non-linear optical chromophore containing a dialkylamino donor group and the dicyanoimidazolyl acceptor separated by a [pi]-conjugated path. The benzene and imidazole rings are not coplanar, making a dihedral angle of 10.0 (2)°. In the crystal, molecules are linked by an extended set of hydrogen bonds and several motifs are recognized. Pairs of molecules are held together by hydrogen bonding between carboxy O-H donor groups and diazenyl N-atom acceptors, forming R22(24) ring patterns across inversion centres. Four-molecule R44(28) ring motifs are formed, again across inversion centres, through hydrogen bonding involving carboxy O-H donor groups and diazenyl and imidazole N-atom acceptors. Four-molecule R44(42) patterns are formed among molecules related by translation and involve carboxy O-H and imidazole N-H donor groups with carbonyl O-atom and imidazole N-atom acceptors.

Comment top

Aromatic heterocycles are playing a fundamental role in modern material chemistry as building blocks of conjugated active molecules in many fields of organic electronics and optoelectronics: conjugated conducting polymers and organic solar cells (Heeger, 2010), organic field-effect transistors (Centore, Ricciotti et al., 2012), nonlinear optically active and piezoelectric compounds (Dalton, 2002; Centore, Concilio et al., 2012). In those fields, the chemical investigation is devoted to the synthesis of new molecules or conjugated polymers containing heterocyclic moieties and to the measurement of their spectroscopic and electronic properties relevant for device performances. However, also the structural investigation of the molecules is a relevant point for the evaluation of the structural parameters related to the conjugation (Carella, Centore, Fort et al., 2004; Gainsford et al., 2008; Capobianco et al., 2012; Capobianco et al., 2013). The rationalization of the local packing modes of chromophore units (Thallapally et al., 2002; Centore & Piccialli, 2012; Centore, Piccialli & Tuzi, 2013) is another crucial point, because many properties required for optimum device performances (e. g. electron mobility) critically depend on the packing not less than on strictly molecular properties. In our research group we are interested in the synthesis of new heterocyclic compounds, including metal containing heterocyclic compounds (Takjoo et al., 2011; Takjoo & Centore, 2013), for applications as advanced materials and bioactive compounds (Piccialli et al., 2013), and in the analysis of crystal structures controlled by the formation of H bonds (Centore, Jazbinsek et al., 2012; Centore, Fusco, Jazbinsek et al., 2013). Following these issues, we report, in the present paper, the structural investigation of the title compound, shown in the Scheme. The title compound is a typical push-pull azo-dye, containing the dialkylamino as donor group and two cyano acceptor groups. Moreover, the cyano groups are attached to an electron poor imidazole ring. The chromophore unit has been used in the synthesis of polymers showing quadratic NLO behaviour (Carella, Centore, Sirigu et al., 2004).

The molecular structure is shown in Fig. 1. The geometry around the donor N1 atom is substantially planar indicating sp2 hybridization (the sum of valence angles at N1 is 360°) and the pattern of bond lenghts within the adjacent phenyl ring shows a certain degree of quinoidal character. All these structural features are in accordance with the expected π conjugation and push-pull character of the chromophore group.

The two aromatic rings are not coplanar, the dihedral angle between the mean planes being 10.0 (2)°; the π-conjugated part of the molecule has a slighlty curved shape, as the result of small torsions around the bonds C10—N2, N2–N3 and N3–C13.

The molecules of the title compound have several H bonding donor and acceptor groups, and the crystal packing is dominated by the formation of H bonds, Table 1. Several H bonding motifs are recognized in the crystal packing (Allen et al., 1999; Steiner, 2002) and some of them are shown in Fig. 2. Couples of molecules are held by H bonding between carboxy O–H donors and azo N acceptors, forming R22(24) ring patterns across inversion centres. Four-molecule ring motifs R44(28) are formed, again across inversion centres, through H bonding involving carboxy O–H donors and azo and imidazole N acceptors. Four-molecule ring motifs R44(42) are formed, among molecules related by translation, through H bonding involving carboxy O–H and imidazole N–H donors and carbonyl and imidazole N acceptors.

Related literature top

For a general survey of advanced materials based on heterocycles, see: Dalton (2002); Heeger (2010). For semiconductor, optoelectronic and piezoelectric materials containing heterocycles, see: Centore, Ricciotti et al. (2012); Centore, Concilio et al. (2012). For structural analysis of conjugation in heterocycle-based organic molecules, see: Carella, Centore, Fort et al. (2004); Gainsford et al. (2008). For structural and theoretical analysis of conjugation in metallorganic compounds containing heterocycles, see: Takjoo et al. (2011); Takjoo & Centore (2013). For theoretical computations on π-conjugated compounds, see: Capobianco et al. (2012, 2013). For the synthesis of related heterocyclic compounds, see: Carella, Centore, Sirigu et al. (2004); Piccialli et al. (2013); Centore, Fusco, Capobianco et al. (2013). For the local packing modes of nonlinear optical chromophores see: Thallapally et al. (2002); Centore & Piccialli (2012); Centore, Piccialli & Tuzi (2013). For hydrogen bonding in crystal structures, see: Allen et al. (1999); Steiner (2002); Centore, Jazbinsek et al. (2012); Centore, Fusco, Jazbinsek et al. (2013). For the synthesis of similar diazo-chromophores, see: Centore et al. (2007).

Experimental top

The title compound was prepared by diazotization of 2-amino-4,5-dicyanoimidazole followed by coupling with N,N-(bis2-carboxyethylamino)aniline. The procedure of diazo-coupling is analogous to that we have already described for the synthesis of similar diazo-chromophores (Centore et al., 2007). Purification was obtained by recrystallization from hot acetic acid. The final yield for the diazotization/coupling step was 91%. Mp. 230 °C (dec). Single crystals were obtained by slow evaporation from acetic acid solutions. 1H-NMR (DMSO-d6) δ 2.45 (tr, 4H), 3.61 (tr, 4H), 6.79 (d, 2H, J = 9 Hz), 7.69 (d, 2H, J = 9 Hz). λmax(DMF) = 452 nm, εmax(DMF)= 2.5 × 10 4 L mol-1cm-1.

Refinement top

The H atoms of the carboxy groups and of the imidazole ring were located in difmaps and their coordinates were refined. All other H atoms were generated stereochemically and were refined by the riding model. For all H atoms Uiso=1.2×Ueq of the carrier atom was assumed.

Computing details top

Data collection: MACH3/PC Software (Nonius, 1996); cell refinement: CELLFITW (Centore, 2004); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures top
[Figure 1] Fig. 1. ORTEP view of the molecular structure of the title compound. Thermal ellipsoids are drawn at 30% probability level.
[Figure 2] Fig. 2. Packing of the title compound viewed along b + c. H bonds are represented by dashed lines.
3,3'-({4-[(4,5-Dicyano-1H-imidazol-2-yl)diazenyl]phenyl}imino)dipropionic acid top
Crystal data top
C17H15N7O4Z = 2
Mr = 381.36F(000) = 396
Triclinic, P1Dx = 1.496 Mg m3
a = 6.895 (5) ÅMo Kα radiation, λ = 0.71073 Å
b = 10.443 (3) ÅCell parameters from 25 reflections
c = 13.373 (3) Åθ = 7.2–9.8°
α = 105.40 (2)°µ = 0.11 mm1
β = 103.96 (4)°T = 293 K
γ = 104.84 (4)°Plate, red
V = 846.5 (7) Å30.26 × 0.13 × 0.07 mm
Data collection top
Enraf–Nonius MACH3
diffractometer
Rint = 0.074
Radiation source: fine-focus sealed tubeθmax = 28.0°, θmin = 1.7°
Graphite monochromatorh = 98
Nonprofiled ω scansk = 1313
4256 measured reflectionsl = 017
4082 independent reflections1 standard reflections every 120 min
1220 reflections with I > 2σ(I) intensity decay: none
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.075Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.216H atoms treated by a mixture of independent and constrained refinement
S = 0.91 w = 1/[σ2(Fo2) + (0.072P)2]
where P = (Fo2 + 2Fc2)/3
4082 reflections(Δ/σ)max < 0.001
262 parametersΔρmax = 0.30 e Å3
0 restraintsΔρmin = 0.33 e Å3
Crystal data top
C17H15N7O4γ = 104.84 (4)°
Mr = 381.36V = 846.5 (7) Å3
Triclinic, P1Z = 2
a = 6.895 (5) ÅMo Kα radiation
b = 10.443 (3) ŵ = 0.11 mm1
c = 13.373 (3) ÅT = 293 K
α = 105.40 (2)°0.26 × 0.13 × 0.07 mm
β = 103.96 (4)°
Data collection top
Enraf–Nonius MACH3
diffractometer
Rint = 0.074
4256 measured reflectionsθmax = 28.0°
4082 independent reflections1 standard reflections every 120 min
1220 reflections with I > 2σ(I) intensity decay: none
Refinement top
R[F2 > 2σ(F2)] = 0.075H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.216Δρmax = 0.30 e Å3
S = 0.91Δρmin = 0.33 e Å3
4082 reflectionsAbsolute structure: ?
262 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Several crystal specimens were tested but their quality was, in general, rather poor, as witnessed by the relatively high fraction of low intensity reflections. The poorly diffracting nature of the crystals is the reason for the relatively high R factors.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.5087 (7)0.2972 (5)0.6271 (4)0.0695 (14)
O20.7415 (7)0.2144 (5)0.5641 (3)0.0546 (13)
H20.828 (10)0.252 (7)0.625 (5)0.065*
O30.6820 (6)0.1393 (4)0.2211 (3)0.0449 (11)
H30.791 (9)0.207 (6)0.168 (4)0.054*
O40.4973 (6)0.2424 (4)0.1314 (3)0.0579 (13)
N10.0479 (6)0.1074 (4)0.3096 (3)0.0347 (11)
N20.1576 (6)0.3969 (4)0.0245 (3)0.0330 (11)
N30.0616 (7)0.3422 (4)0.0794 (4)0.0351 (11)
N40.2872 (7)0.5635 (5)0.0763 (4)0.0321 (12)
H40.327 (8)0.603 (6)0.010 (4)0.039*
N50.0928 (6)0.3985 (4)0.2380 (3)0.0350 (11)
N60.2377 (9)0.5392 (6)0.4342 (5)0.0736 (18)
N70.5606 (7)0.8734 (5)0.1101 (4)0.0530 (15)
C10.5542 (10)0.2307 (6)0.5524 (5)0.0443 (16)
C20.4013 (8)0.1581 (6)0.4388 (4)0.0410 (15)
H2A0.38510.05860.41650.049*
H2B0.46040.19650.38980.049*
C30.1838 (8)0.1715 (6)0.4252 (4)0.0390 (14)
H3A0.11750.12540.46850.047*
H3B0.19900.27070.45220.047*
C40.5053 (8)0.1506 (6)0.2034 (4)0.0360 (14)
C50.3145 (8)0.0271 (6)0.2831 (4)0.0443 (15)
H5A0.31440.01900.35700.053*
H5B0.32940.05820.27140.053*
C60.1030 (8)0.0340 (6)0.2757 (4)0.0379 (14)
H6A0.05010.08280.32260.045*
H6B0.11970.08670.20070.045*
C70.0604 (7)0.1772 (6)0.2383 (4)0.0327 (13)
C80.0607 (8)0.1135 (5)0.1257 (4)0.0327 (13)
H80.16070.02320.10050.039*
C90.0354 (7)0.1804 (5)0.0534 (4)0.0318 (13)
H90.11380.13310.02080.038*
C100.1061 (7)0.3192 (5)0.0874 (4)0.0319 (13)
C110.2172 (8)0.3865 (5)0.2009 (4)0.0354 (14)
H110.30790.47970.22620.042*
C120.1978 (8)0.3213 (5)0.2750 (4)0.0350 (13)
H120.27320.37000.34940.042*
C130.1445 (7)0.4320 (5)0.1300 (4)0.0303 (13)
C140.3292 (8)0.6199 (5)0.1517 (4)0.0342 (14)
C150.2101 (8)0.5140 (6)0.2531 (4)0.0371 (14)
C160.4603 (8)0.7600 (6)0.1284 (4)0.0382 (14)
C170.2170 (9)0.5250 (6)0.3564 (5)0.0457 (16)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.074 (3)0.066 (3)0.041 (3)0.025 (3)0.002 (2)0.005 (2)
O20.041 (3)0.058 (3)0.042 (3)0.008 (2)0.007 (2)0.010 (2)
O30.031 (2)0.048 (3)0.039 (2)0.0005 (19)0.0067 (19)0.007 (2)
O40.051 (3)0.051 (3)0.040 (2)0.001 (2)0.010 (2)0.013 (2)
N10.031 (2)0.030 (3)0.029 (3)0.002 (2)0.001 (2)0.008 (2)
N20.030 (2)0.030 (3)0.030 (3)0.005 (2)0.007 (2)0.005 (2)
N30.037 (3)0.030 (3)0.034 (3)0.007 (2)0.012 (2)0.009 (2)
N40.029 (2)0.025 (3)0.030 (2)0.001 (2)0.006 (2)0.003 (2)
N50.027 (2)0.030 (3)0.035 (3)0.003 (2)0.001 (2)0.010 (2)
N60.074 (4)0.083 (5)0.053 (4)0.009 (3)0.015 (3)0.029 (3)
N70.044 (3)0.040 (3)0.067 (4)0.005 (3)0.020 (3)0.015 (3)
C10.052 (4)0.030 (4)0.037 (4)0.005 (3)0.002 (3)0.010 (3)
C20.041 (3)0.040 (4)0.033 (3)0.007 (3)0.003 (3)0.012 (3)
C30.033 (3)0.041 (4)0.033 (3)0.001 (3)0.007 (3)0.011 (3)
C40.034 (3)0.038 (4)0.031 (3)0.004 (3)0.007 (3)0.015 (3)
C50.039 (3)0.040 (4)0.039 (3)0.000 (3)0.011 (3)0.005 (3)
C60.034 (3)0.035 (3)0.034 (3)0.002 (3)0.005 (3)0.010 (3)
C70.021 (3)0.029 (3)0.035 (3)0.005 (2)0.005 (2)0.000 (3)
C80.027 (3)0.026 (3)0.036 (3)0.002 (2)0.006 (2)0.007 (3)
C90.029 (3)0.024 (3)0.030 (3)0.002 (2)0.002 (2)0.007 (2)
C100.022 (3)0.032 (3)0.032 (3)0.009 (2)0.002 (2)0.002 (3)
C110.033 (3)0.025 (3)0.040 (3)0.002 (2)0.012 (3)0.006 (3)
C120.035 (3)0.033 (3)0.024 (3)0.006 (3)0.005 (2)0.000 (2)
C130.024 (3)0.033 (3)0.028 (3)0.008 (2)0.006 (2)0.006 (2)
C140.029 (3)0.031 (3)0.036 (3)0.005 (3)0.008 (2)0.008 (3)
C150.028 (3)0.042 (4)0.031 (3)0.007 (3)0.003 (2)0.008 (3)
C160.031 (3)0.038 (4)0.045 (4)0.011 (3)0.013 (3)0.014 (3)
C170.040 (3)0.049 (4)0.037 (4)0.004 (3)0.006 (3)0.014 (3)
Geometric parameters (Å, º) top
O1—C11.213 (7)C2—H2B0.9700
O2—C11.323 (7)C3—H3A0.9700
O2—H20.80 (6)C3—H3B0.9700
O3—C41.324 (7)C4—C51.502 (7)
O3—H30.88 (5)C5—C61.504 (7)
O4—C41.187 (6)C5—H5A0.9700
N1—C71.350 (7)C5—H5B0.9700
N1—C61.449 (6)C6—H6A0.9700
N1—C31.465 (6)C6—H6B0.9700
N2—N31.278 (5)C7—C81.408 (7)
N2—C101.361 (6)C7—C121.434 (7)
N3—C131.384 (6)C8—C91.353 (7)
N4—C131.346 (6)C8—H80.9300
N4—C141.347 (7)C9—C101.404 (7)
N4—H40.81 (5)C9—H90.9300
N5—C131.325 (6)C10—C111.408 (7)
N5—C151.363 (6)C11—C121.356 (7)
N6—C171.127 (7)C11—H110.9300
N7—C161.133 (6)C12—H120.9300
C1—C21.483 (7)C14—C151.392 (7)
C2—C31.514 (7)C14—C161.415 (8)
C2—H2A0.9700C15—C171.427 (8)
C1—O2—H2116 (5)N1—C6—C5110.1 (4)
C4—O3—H3108 (4)N1—C6—H6A109.6
C7—N1—C6121.5 (4)C5—C6—H6A109.6
C7—N1—C3121.7 (4)N1—C6—H6B109.6
C6—N1—C3116.7 (4)C5—C6—H6B109.6
N3—N2—C10118.0 (4)H6A—C6—H6B108.2
N2—N3—C13109.7 (4)N1—C7—C8122.1 (5)
C13—N4—C14108.1 (4)N1—C7—C12120.9 (5)
C13—N4—H4124 (4)C8—C7—C12117.0 (5)
C14—N4—H4127 (4)C9—C8—C7121.7 (5)
C13—N5—C15105.1 (4)C9—C8—H8119.1
O1—C1—O2123.8 (6)C7—C8—H8119.1
O1—C1—C2122.5 (6)C8—C9—C10121.7 (5)
O2—C1—C2113.7 (6)C8—C9—H9119.1
C1—C2—C3114.2 (5)C10—C9—H9119.1
C1—C2—H2A108.7N2—C10—C9128.5 (5)
C3—C2—H2A108.7N2—C10—C11114.8 (4)
C1—C2—H2B108.7C9—C10—C11116.6 (5)
C3—C2—H2B108.7C12—C11—C10122.9 (5)
H2A—C2—H2B107.6C12—C11—H11118.6
N1—C3—C2111.0 (4)C10—C11—H11118.6
N1—C3—H3A109.4C11—C12—C7119.8 (5)
C2—C3—H3A109.4C11—C12—H12120.1
N1—C3—H3B109.4C7—C12—H12120.1
C2—C3—H3B109.4N5—C13—N4111.6 (5)
H3A—C3—H3B108.0N5—C13—N3123.9 (4)
O4—C4—O3125.1 (5)N4—C13—N3124.5 (4)
O4—C4—C5123.8 (5)N4—C14—C15105.3 (5)
O3—C4—C5111.0 (5)N4—C14—C16125.5 (5)
C4—C5—C6115.5 (5)C15—C14—C16129.1 (5)
C4—C5—H5A108.4N5—C15—C14109.8 (5)
C6—C5—H5A108.4N5—C15—C17125.8 (5)
C4—C5—H5B108.4C14—C15—C17124.4 (5)
C6—C5—H5B108.4N7—C16—C14178.1 (6)
H5A—C5—H5B107.5N6—C17—C15175.0 (6)
C10—N2—N3—C13175.9 (4)C9—C10—C11—C122.4 (8)
O1—C1—C2—C31.3 (8)C10—C11—C12—C70.5 (8)
O2—C1—C2—C3177.9 (5)N1—C7—C12—C11176.1 (5)
C7—N1—C3—C281.8 (6)C8—C7—C12—C114.6 (7)
C6—N1—C3—C299.1 (5)C15—N5—C13—N40.6 (6)
C1—C2—C3—N1175.3 (5)C15—N5—C13—N3179.4 (5)
O4—C4—C5—C67.2 (8)C14—N4—C13—N50.9 (6)
O3—C4—C5—C6175.8 (5)C14—N4—C13—N3179.2 (5)
C7—N1—C6—C585.4 (6)N2—N3—C13—N5172.9 (5)
C3—N1—C6—C593.7 (6)N2—N3—C13—N47.0 (7)
C4—C5—C6—N1150.8 (5)C13—N4—C14—C152.0 (6)
C6—N1—C7—C84.7 (8)C13—N4—C14—C16175.5 (5)
C3—N1—C7—C8176.2 (5)C13—N5—C15—C141.8 (6)
C6—N1—C7—C12174.7 (5)C13—N5—C15—C17176.3 (6)
C3—N1—C7—C124.4 (7)N4—C14—C15—N52.4 (6)
N1—C7—C8—C9174.8 (5)C16—C14—C15—N5175.0 (5)
C12—C7—C8—C95.8 (8)N4—C14—C15—C17175.8 (5)
C7—C8—C9—C102.9 (8)C16—C14—C15—C176.9 (10)
N3—N2—C10—C93.2 (8)N4—C14—C16—N792 (19)
N3—N2—C10—C11179.6 (5)C15—C14—C16—N785 (19)
C8—C9—C10—N2175.9 (5)N5—C15—C17—N6143 (8)
C8—C9—C10—C111.3 (7)C14—C15—C17—N635 (9)
N2—C10—C11—C12175.1 (5)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···N5i0.80 (6)2.12 (6)2.896 (6)162 (6)
O3—H3···N3ii0.88 (5)1.89 (6)2.750 (6)165 (5)
N4—H4···O4iii0.81 (5)1.98 (5)2.740 (6)156 (5)
Symmetry codes: (i) x+1, y, z+1; (ii) x1, y, z; (iii) x+1, y+1, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···N5i0.80 (6)2.12 (6)2.896 (6)162 (6)
O3—H3···N3ii0.88 (5)1.89 (6)2.750 (6)165 (5)
N4—H4···O4iii0.81 (5)1.98 (5)2.740 (6)156 (5)
Symmetry codes: (i) x+1, y, z+1; (ii) x1, y, z; (iii) x+1, y+1, z.
Acknowledgements top

The authors thank the Centro Interdipartimentale di Metodologie Chimico –Fisiche, Università degli Studi di Napoli "Federico II".

references
References top

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