Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270105027320/bm1616sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270105027320/bm1616Isup2.hkl |
CCDC reference: 288631
When an equimolar mixture of dpknph and CdCl2 dissolved in acetonitrile was subjected to ultrasonic radiation for an hour, and the filtrate of the reaction mixture was allowed to stand at room temperature for several days, an orange crystal originally thought to be Cd(dpknph)Cl2 was isolated.
##AUTHOR: Please check wording below: All H atoms of β-dpknph were assigned by assuming idealized geometry with C—H distances of 0.93 Å and with Uiso(H) valus of 1.2Ueq(carrier). The N-bound atom H4 was refined freely.
Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXTL.
C17H13N5O2 | F(000) = 664 |
Mr = 319.32 | Dx = 1.384 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 7.9415 (9) Å | Cell parameters from 2735 reflections |
b = 22.123 (3) Å | θ = 2.5–23.0° |
c = 8.9747 (10) Å | µ = 0.10 mm−1 |
β = 103.606 (2)° | T = 296 K |
V = 1532.5 (3) Å3 | Plate, orange |
Z = 4 | 0.32 × 0.22 × 0.12 mm |
Bruker SMART CCD area detector diffractometer | 1961 reflections with I > 2σ(I) |
Radiation source: sealed tube | Rint = 0.053 |
Graphite monochromator | θmax = 28.2°, θmin = 1.8° |
ω scans | h = −10→10 |
13621 measured reflections | k = −28→28 |
3630 independent reflections | l = −11→11 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.095 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.87 | w = 1/[σ2(Fo2) + (0.0426P)2] where P = (Fo2 + 2Fc2)/3 |
3630 reflections | (Δ/σ)max < 0.001 |
221 parameters | Δρmax = 0.13 e Å−3 |
0 restraints | Δρmin = −0.12 e Å−3 |
C17H13N5O2 | V = 1532.5 (3) Å3 |
Mr = 319.32 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.9415 (9) Å | µ = 0.10 mm−1 |
b = 22.123 (3) Å | T = 296 K |
c = 8.9747 (10) Å | 0.32 × 0.22 × 0.12 mm |
β = 103.606 (2)° |
Bruker SMART CCD area detector diffractometer | 1961 reflections with I > 2σ(I) |
13621 measured reflections | Rint = 0.053 |
3630 independent reflections |
R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.095 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.87 | Δρmax = 0.13 e Å−3 |
3630 reflections | Δρmin = −0.12 e Å−3 |
221 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | −0.06012 (15) | 0.32563 (6) | 0.53397 (14) | 0.0962 (4) | |
O2 | −0.03396 (19) | 0.25831 (7) | 0.36814 (16) | 0.1159 (5) | |
N1 | 0.33555 (14) | 0.51718 (6) | −0.17277 (13) | 0.0602 (3) | |
N2 | 0.59254 (15) | 0.64328 (6) | 0.14887 (14) | 0.0697 (4) | |
N3 | 0.27824 (14) | 0.53816 (6) | 0.13165 (13) | 0.0565 (3) | |
N4 | 0.21419 (14) | 0.48522 (6) | 0.06532 (15) | 0.0585 (3) | |
H4 | 0.2411 (17) | 0.4755 (6) | −0.0302 (17) | 0.071 (5)* | |
N5 | −0.02572 (16) | 0.31079 (8) | 0.41359 (17) | 0.0749 (4) | |
C11 | 0.34965 (18) | 0.51277 (8) | −0.31752 (18) | 0.0684 (4) | |
H11 | 0.3266 | 0.4755 | −0.3661 | 0.082* | |
C12 | 0.39607 (19) | 0.55979 (9) | −0.39921 (18) | 0.0732 (5) | |
H12 | 0.4034 | 0.5546 | −0.5003 | 0.088* | |
C13 | 0.43128 (19) | 0.61450 (9) | −0.32759 (19) | 0.0752 (5) | |
H13 | 0.4634 | 0.6473 | −0.3794 | 0.090* | |
C14 | 0.41865 (18) | 0.62038 (8) | −0.17860 (18) | 0.0667 (4) | |
H14 | 0.4417 | 0.6574 | −0.1287 | 0.080* | |
C15 | 0.37129 (16) | 0.57091 (7) | −0.10231 (16) | 0.0548 (4) | |
C01 | 0.35261 (16) | 0.57601 (6) | 0.05695 (16) | 0.0537 (4) | |
C21 | 0.6654 (2) | 0.68859 (8) | 0.2393 (2) | 0.0798 (5) | |
H21 | 0.7790 | 0.6989 | 0.2395 | 0.096* | |
C22 | 0.5841 (2) | 0.72098 (8) | 0.33193 (19) | 0.0787 (5) | |
H22 | 0.6412 | 0.7522 | 0.3930 | 0.094* | |
C23 | 0.4167 (2) | 0.70631 (8) | 0.33234 (19) | 0.0750 (5) | |
H23 | 0.3573 | 0.7276 | 0.3933 | 0.090* | |
C24 | 0.33807 (19) | 0.65968 (7) | 0.24146 (18) | 0.0651 (4) | |
H24 | 0.2245 | 0.6489 | 0.2403 | 0.078* | |
C25 | 0.42854 (17) | 0.62882 (6) | 0.15181 (15) | 0.0558 (4) | |
C31 | 0.14816 (15) | 0.44382 (7) | 0.15104 (16) | 0.0519 (4) | |
C32 | 0.11948 (17) | 0.45811 (7) | 0.29379 (16) | 0.0608 (4) | |
H32 | 0.1400 | 0.4971 | 0.3322 | 0.073* | |
C33 | 0.06078 (17) | 0.41454 (8) | 0.37806 (16) | 0.0634 (4) | |
H33 | 0.0420 | 0.4239 | 0.4739 | 0.076* | |
C34 | 0.02985 (16) | 0.35701 (7) | 0.32037 (17) | 0.0578 (4) | |
C35 | 0.05154 (17) | 0.34245 (7) | 0.17694 (17) | 0.0630 (4) | |
H35 | 0.0270 | 0.3037 | 0.1379 | 0.076* | |
C36 | 0.10985 (17) | 0.38589 (7) | 0.09253 (16) | 0.0609 (4) | |
H36 | 0.1240 | 0.3766 | −0.0048 | 0.073* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0899 (8) | 0.1326 (11) | 0.0772 (9) | 0.0037 (7) | 0.0422 (7) | 0.0310 (8) |
O2 | 0.1486 (13) | 0.0925 (11) | 0.1123 (11) | −0.0404 (9) | 0.0424 (9) | 0.0082 (9) |
N1 | 0.0533 (7) | 0.0753 (9) | 0.0532 (8) | 0.0093 (6) | 0.0151 (6) | 0.0099 (7) |
N2 | 0.0538 (7) | 0.0886 (10) | 0.0692 (9) | −0.0019 (7) | 0.0195 (6) | 0.0004 (7) |
N3 | 0.0466 (6) | 0.0653 (8) | 0.0589 (8) | 0.0084 (6) | 0.0149 (6) | 0.0098 (7) |
N4 | 0.0536 (7) | 0.0722 (9) | 0.0528 (8) | 0.0023 (6) | 0.0187 (6) | 0.0087 (7) |
N5 | 0.0565 (8) | 0.0970 (12) | 0.0715 (10) | −0.0063 (8) | 0.0156 (7) | 0.0210 (9) |
C11 | 0.0638 (10) | 0.0872 (12) | 0.0552 (10) | 0.0111 (8) | 0.0162 (8) | 0.0052 (9) |
C12 | 0.0655 (10) | 0.1068 (15) | 0.0505 (10) | 0.0151 (10) | 0.0201 (8) | 0.0171 (10) |
C13 | 0.0677 (10) | 0.0948 (13) | 0.0651 (11) | 0.0045 (9) | 0.0194 (8) | 0.0273 (10) |
C14 | 0.0632 (9) | 0.0772 (11) | 0.0603 (10) | 0.0054 (8) | 0.0159 (8) | 0.0168 (8) |
C15 | 0.0403 (7) | 0.0720 (10) | 0.0527 (9) | 0.0121 (7) | 0.0118 (6) | 0.0161 (8) |
C01 | 0.0424 (7) | 0.0652 (9) | 0.0559 (9) | 0.0114 (7) | 0.0160 (6) | 0.0159 (8) |
C25 | 0.0526 (8) | 0.0635 (9) | 0.0537 (9) | 0.0074 (7) | 0.0171 (7) | 0.0156 (7) |
C24 | 0.0618 (9) | 0.0661 (10) | 0.0736 (11) | 0.0059 (8) | 0.0286 (8) | 0.0096 (9) |
C23 | 0.0872 (12) | 0.0714 (11) | 0.0750 (12) | 0.0065 (10) | 0.0366 (9) | 0.0042 (9) |
C22 | 0.0835 (12) | 0.0811 (12) | 0.0713 (11) | −0.0065 (10) | 0.0183 (9) | −0.0027 (9) |
C21 | 0.0608 (10) | 0.1012 (14) | 0.0770 (12) | −0.0100 (9) | 0.0158 (9) | −0.0016 (11) |
C31 | 0.0373 (7) | 0.0685 (10) | 0.0509 (9) | 0.0055 (7) | 0.0122 (6) | 0.0112 (7) |
C32 | 0.0578 (9) | 0.0700 (10) | 0.0585 (10) | 0.0006 (7) | 0.0212 (7) | 0.0004 (8) |
C33 | 0.0558 (8) | 0.0880 (12) | 0.0500 (9) | 0.0020 (8) | 0.0200 (7) | 0.0048 (9) |
C34 | 0.0416 (7) | 0.0744 (11) | 0.0582 (9) | −0.0019 (7) | 0.0130 (7) | 0.0131 (8) |
C35 | 0.0540 (9) | 0.0711 (10) | 0.0656 (10) | −0.0043 (7) | 0.0176 (7) | −0.0004 (8) |
C36 | 0.0549 (8) | 0.0786 (11) | 0.0514 (9) | −0.0008 (8) | 0.0172 (7) | 0.0015 (8) |
N3—N4 | 1.3574 (16) | C24—H24 | 0.9300 |
N4—H4 | 0.956 (15) | C23—C22 | 1.370 (2) |
N5—O1 | 1.2200 (17) | C23—H23 | 0.9300 |
N5—O2 | 1.2273 (17) | C22—C21 | 1.369 (2) |
C11—N1 | 1.3334 (17) | C22—H22 | 0.9300 |
C11—C12 | 1.372 (2) | C21—N2 | 1.3332 (19) |
C11—H11 | 0.9300 | C21—H21 | 0.9300 |
C12—C13 | 1.368 (2) | C31—N4 | 1.3767 (16) |
C12—H12 | 0.9300 | C31—C32 | 1.3894 (18) |
C13—C14 | 1.370 (2) | C31—C36 | 1.3913 (19) |
C13—H13 | 0.9300 | C32—C33 | 1.373 (2) |
C14—C15 | 1.3890 (19) | C32—H32 | 0.9300 |
C14—H14 | 0.9300 | C33—C34 | 1.374 (2) |
C15—N1 | 1.3450 (17) | C33—H33 | 0.9300 |
C15—C01 | 1.4757 (19) | C34—C35 | 1.3766 (19) |
C01—N3 | 1.2983 (16) | C34—N5 | 1.4539 (19) |
C01—C25 | 1.4873 (19) | C35—C36 | 1.3700 (19) |
C25—N2 | 1.3474 (16) | C35—H35 | 0.9300 |
C25—C24 | 1.3790 (18) | C36—H36 | 0.9300 |
C24—C23 | 1.371 (2) | ||
N1—C11—C12 | 124.04 (16) | N2—C21—C22 | 124.33 (15) |
N1—C11—H11 | 118.0 | N2—C21—H21 | 117.8 |
C12—C11—H11 | 118.0 | C22—C21—H21 | 117.8 |
C13—C12—C11 | 118.08 (16) | N4—C31—C32 | 122.05 (14) |
C13—C12—H12 | 121.0 | N4—C31—C36 | 118.69 (13) |
C11—C12—H12 | 121.0 | C32—C31—C36 | 119.26 (13) |
C12—C13—C14 | 119.25 (16) | C33—C32—C31 | 119.93 (15) |
C12—C13—H13 | 120.4 | C33—C32—H32 | 120.0 |
C14—C13—H13 | 120.4 | C31—C32—H32 | 120.0 |
C13—C14—C15 | 119.78 (16) | C32—C33—C34 | 119.77 (14) |
C13—C14—H14 | 120.1 | C32—C33—H33 | 120.1 |
C15—C14—H14 | 120.1 | C34—C33—H33 | 120.1 |
N1—C15—C14 | 121.08 (14) | C33—C34—C35 | 121.23 (14) |
N1—C15—C01 | 117.70 (13) | C33—C34—N5 | 119.08 (15) |
C14—C15—C01 | 121.19 (15) | C35—C34—N5 | 119.68 (15) |
N3—C01—C15 | 127.77 (14) | C36—C35—C34 | 119.06 (15) |
N3—C01—C25 | 112.55 (13) | C36—C35—H35 | 120.5 |
C15—C01—C25 | 119.66 (12) | C34—C35—H35 | 120.5 |
N2—C25—C24 | 122.18 (14) | C35—C36—C31 | 120.66 (14) |
N2—C25—C01 | 116.03 (12) | C35—C36—H36 | 119.7 |
C24—C25—C01 | 121.75 (13) | C31—C36—H36 | 119.7 |
C23—C24—C25 | 119.53 (15) | C11—N1—C15 | 117.77 (13) |
C23—C24—H24 | 120.2 | C21—N2—C25 | 116.74 (13) |
C25—C24—H24 | 120.2 | C01—N3—N4 | 119.94 (12) |
C22—C23—C24 | 118.89 (15) | N3—N4—C31 | 118.79 (13) |
C22—C23—H23 | 120.6 | N3—N4—H4 | 116.6 (8) |
C24—C23—H23 | 120.6 | C31—N4—H4 | 123.2 (8) |
C21—C22—C23 | 118.33 (16) | O1—N5—O2 | 122.91 (15) |
C21—C22—H22 | 120.8 | O1—N5—C34 | 118.81 (16) |
C23—C22—H22 | 120.8 | O2—N5—C34 | 118.28 (15) |
N1—C11—C12—C13 | 0.5 (2) | C32—C33—C34—N5 | 177.59 (12) |
C11—C12—C13—C14 | −0.2 (2) | C33—C34—C35—C36 | 1.9 (2) |
C12—C13—C14—C15 | 0.3 (2) | N5—C34—C35—C36 | −177.71 (12) |
C13—C14—C15—N1 | −0.7 (2) | C34—C35—C36—C31 | 0.5 (2) |
C13—C14—C15—C01 | −178.60 (12) | N4—C31—C36—C35 | 176.95 (12) |
N1—C15—C01—N3 | −12.55 (19) | C32—C31—C36—C35 | −2.81 (19) |
C14—C15—C01—N3 | 165.38 (13) | C12—C11—N1—C15 | −0.9 (2) |
N1—C15—C01—C25 | 165.75 (11) | C14—C15—N1—C11 | 1.00 (18) |
C14—C15—C01—C25 | −16.32 (18) | C01—C15—N1—C11 | 178.93 (11) |
N3—C01—C25—N2 | 131.90 (12) | C22—C21—N2—C25 | −0.7 (2) |
C15—C01—C25—N2 | −46.65 (16) | C24—C25—N2—C21 | 1.1 (2) |
N3—C01—C25—C24 | −45.90 (17) | C01—C25—N2—C21 | −176.70 (13) |
C15—C01—C25—C24 | 135.55 (13) | C15—C01—N3—N4 | 3.48 (19) |
N2—C25—C24—C23 | −0.7 (2) | C25—C01—N3—N4 | −174.92 (10) |
C01—C25—C24—C23 | 176.97 (13) | C01—N3—N4—C31 | 174.98 (11) |
C25—C24—C23—C22 | −0.2 (2) | C32—C31—N4—N3 | 10.51 (18) |
C24—C23—C22—C21 | 0.5 (2) | C36—C31—N4—N3 | −169.25 (11) |
C23—C22—C21—N2 | −0.1 (3) | C33—C34—N5—O1 | 7.25 (19) |
N4—C31—C32—C33 | −177.07 (12) | C35—C34—N5—O1 | −173.14 (13) |
C36—C31—C32—C33 | 2.68 (19) | C33—C34—N5—O2 | −171.92 (14) |
C31—C32—C33—C34 | −0.3 (2) | C35—C34—N5—O2 | 7.7 (2) |
C32—C33—C34—C35 | −2.0 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N4—H4···N1 | 0.956 (15) | 1.871 (15) | 2.6389 (16) | 135.5 (12) |
C14—H14···N2 | 0.93 | 2.52 | 2.982 (2) | 111 |
Experimental details
Crystal data | |
Chemical formula | C17H13N5O2 |
Mr | 319.32 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 296 |
a, b, c (Å) | 7.9415 (9), 22.123 (3), 8.9747 (10) |
β (°) | 103.606 (2) |
V (Å3) | 1532.5 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.10 |
Crystal size (mm) | 0.32 × 0.22 × 0.12 |
Data collection | |
Diffractometer | Bruker SMART CCD area detector diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 13621, 3630, 1961 |
Rint | 0.053 |
(sin θ/λ)max (Å−1) | 0.665 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.095, 0.87 |
No. of reflections | 3630 |
No. of parameters | 221 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.13, −0.12 |
Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SAINT, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1997) and PLATON (Spek, 2003), SHELXTL.
N3—N4 | 1.3574 (16) | C01—N3 | 1.2983 (16) |
N5—O1 | 1.2200 (17) | C01—C25 | 1.4873 (19) |
C11—N1 | 1.3334 (17) | C25—N2 | 1.3474 (16) |
C11—C12 | 1.372 (2) | C31—N4 | 1.3767 (16) |
C15—N1 | 1.3450 (17) | C34—N5 | 1.4539 (19) |
C15—C01 | 1.4757 (19) | ||
C14—C15—C01 | 121.19 (15) | N4—C31—C32 | 122.05 (14) |
N3—C01—C15 | 127.77 (14) | C01—N3—N4 | 119.94 (12) |
N3—C01—C25 | 112.55 (13) | N3—N4—C31 | 118.79 (13) |
C15—C01—C25 | 119.66 (12) | O1—N5—O2 | 122.91 (15) |
N2—C25—C01 | 116.03 (12) | ||
N1—C15—C01—N3 | −12.55 (19) | C15—C01—C25—N2 | −46.65 (16) |
C14—C15—C01—N3 | 165.38 (13) | N3—C01—C25—C24 | −45.90 (17) |
N1—C15—C01—C25 | 165.75 (11) | C15—C01—N3—N4 | 3.48 (19) |
C14—C15—C01—C25 | −16.32 (18) | C25—C01—N3—N4 | −174.92 (10) |
N3—C01—C25—N2 | 131.90 (12) | C01—N3—N4—C31 | 174.98 (11) |
D—H···A | D—H | H···A | D···A | D—H···A |
N4—H4···N1 | 0.956 (15) | 1.871 (15) | 2.6389 (16) | 135.5 (12) |
C14—H14···N2 | 0.93 | 2.52 | 2.982 (2) | 111 |
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In recent reports (Bakir & Abdur-Rashid, 1999; Bakir, 2001; Bakir & Brown, 2002; Bakir & Gyles, 2002; Bakir et al., 2000, 2003, 2005) we described the synthesis, structures and reactions of di-2-pyridyl ketone 4-nitrophenylhydrazone (dpknph) and its metal complexes, which revealed a high sensitivity of dpknph and its metal compounds to slight variations in their surroundings. Optosensing measurements on dpknph show a reversible interconversion between two charge transfer electronic states, and substrates with concentrations as low as 1.00x10−7 M can be detected and measured using dpknph in DMSO (dimethyl sulfoxide). Thermo-optical measurements on dpknph in DMSO confirmed the reversible interconversion between high- and low-energy electronic states of dpknph, and allowed for the calculations of their thermodynamic activation parameters. Thus changes in enthalpy (ΔHϕ) of 249.05 ± 1.25 kJ mol−1, entropy (ΔSϕ) of + 0.16 ± 0.04 kJ mol−1 and free energy (ΔGϕ) of −96.30 ± 2.45 kJ mol−1 were determined at 295 K.
Although several attempts were made to explore the polymorphic behavior of di-2-pyridyl ketone (dpk) hydrazones and their metal compounds, prior to this report we were not able to isolate any polymorphic form of dpk hydrazone. In the course of exploring the optosensing behavior and reactions of dpknph with group 12 metal halides in acetonitrile, a new polymorphic form of dpknph was isolated when the filtrate of a sonicated acetonitrile solution of dpknph and CdCl2 was allowed to stand at room temperature for several days. We have designated this polymorph β-dpknph.
##AUTHOR: The non-classical C14—H14···N2 hydrogen bond is a bit improbable, given the rather acute angle of 111.2 degrees. I have removed it from the discussion but left it in the hydrogen bond geometry loop.
A view of the molecular structure of β-dpknph is shown in Fig. 1. With the exception of slight variations of less than 4° in bond angles about the bridging carbon atom (C01) of the dpk moiety, there are no significant variations in bond distances and valence angles between the molecules in the α- and β-dpknph forms. However, pronounced differences between α- and β-dpknph are apparent in the conformation of the pyridine rings about the bridging C atom of the dpk moiety (see Table 1). In the case of β-dpknph, atom N1 is in close proximity to atom N4, and atom N2 is in close proximity proximity to atom C14 (see Fig. 1). This orientation is the result of a classical intramolecular N—H···N hydrogen bond between atoms N1 and N4. The bond distances and angle of the hydrogen bonds (see Table 2) are similar to those in a variety of compounds containing such bonds; for example, in di-2-pyridyl ketone p-aminobenzoylhydrazone hydrate (dpkbz·H2O; Bakir & Green, 2002), hydrogen-bonding parameters D—H, H···A, D···A and D—H···A of 0.86, 2.01, 2.656 (2) Å and 131° were observed for the classical N—H···N hydrogen bond and values of 0.93, 2.52, 3.325 (2) Å and 142° were observed for a non-classical C—H···O hydrogen bond. In the case of α-dpknph, the 4-nitrophenylhydrazone moiety and the N1 pyridine ring are coplanar and orthogonal to the N2 pyridine ring, and hence do not allow for the formation of any suitable intramolecular hydrogen bonding.
In β-dpknph, torsion angles of −12.55 (19) and 131.90 (12)° were observed for N3—C01—C15—N1 and N3—C01—C25—N2, respectively, while for α-dpknph the analogous angles are 94.4 (3) and 176.1 (2)°. The pyridine rings in α-dpknph are nearly perpendicular [dihedral angle ??.?? (s.u.)°], while in the case of β-dpknph the dihedral angle between the pyridine rings is 56.36 (12)°.
The packing of β-dpknph molecules along the c axis, shown in Fig. 2, reveals parallel stacks of β-dpknph molecules aong the a axis and the absence of intermolecular interactions such as hydrogen-bonding between stacks. Alternate molecules in the stacks are related by inversion. This packing pattern contrasts with the interlocked, interdigitated packing behavior of α-dpknph (see Fig. 3), which also displayed an extensive network of non-covalent intermolecular interactions, namely N1···N4, N2···C14 and C11···O2 (see Fig. 4).
In conclusion, a second polymorphic form of dpknph has been isolated, and the solid-state structural analysis reveals significant conformational differences between α- and β-dpknph as manifested by the orientation of the pyridine rings around the bridging C atom of dpk and the differing types of intermolecular hydrogen-bonding interactions. The rich physicochemical properties of hydrazones and their metal complexes has led to a number of possible applications in, for example, nonlinear optics and molecular sensing. We are therefore actively exploring the structures of a variety of di-2-pyridyl ketone hydrazones.