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Acta Cryst. (2009). E65, o768-o769    [ doi:10.1107/S1600536809008551 ]

9-Chloro-2,4-dimethoxyacridinium trifluoromethanesulfonate

B. Zadykowicz, K. Krzyminski, D. Trzybinski, A. Sikorski and J. Blazejowski

Abstract top

In the molecular structure of the title compound, C15H13ClNO2+·CF3SO3-, the methoxy groups are nearly coplanar with the acridine ring system, making dihedral angles of 0.4 (2) and 5.1 (2)°. Multidirectional [pi]-[pi] contacts between acridine units are observed in the crystal structure. N-H...O and C-H...O hydrogen bonds link cations and anions, forming a layer structure.

Comment top

Acridinium cations containing various substituents at position 9 and alkyl-substituted at the endocyclic N atom (position 10) undergo oxidation by H2O2 or other peroxides in alkaline media, which leads to the formation of electronically excited 10-alkyl-9-acridinones capable of emitting light with a quantum yield of several percent (Zomer & Jacquemijns, 2001; Wróblewska et al., 2004). This chemiluminescence is affected by the features of the substituent at position 9 and by the constitution of the acridine fragment. In the search for derivatives that could exhibit an enhanced chemiluminogenic ability we turned our attention to compounds in which the C atom at position 9 is bound to a Cl atom. One of the compounds synthesized was 9-chloro-2,4-dimethoxyacridinium trifluoromethanesulfonate. This compound was obtained by the reaction of 9-chloro-2,4-dimethoxyacridine with methyl trifluoromethanesulfonate, which usually leads to quarternarization of the endocyclic N atom (Sato, 1996). Since this did not happen, it is possible that traces of water caused the transformation of methyl trifluoromethanesulfonate to trifluoromethanesulfonic acid and methanol, and the reaction of the former entity with 9-chloro-2,4-dimethoxyacridine to yield 9-chloro-2,4-dimethoxyacridinium trifluoromethanesulfonate. The cation of the title compound has a protonated endocyclic N-atom, which makes its reaction with oxidants possible. On the other hand, substitution in the acridine moiety by two methoxy groups should cause a red shift of the chemiluminescence emission, advantageous in analytical applications. 9-Chloroacridines have been precursors of numerous 9-substitued acridine derivatives (Acheson, 1973; Wróblewska et al., 2004), including drugs (Acheson, 1973; Demeunynck et al., 2001). This paper presents the crystal structure of the title compound.

The acridine units, with an average deviation from planarity of 0.025 (5) Å, are parallel in the crystal lattice. In the cation of the title compound (Fig. 1) the bond lengths and angles characterizing the geometry of the 9-chloroacridine skeleton are similar to those in 9-chloroacridine itself (Achari & Neidle, 1977), a 9-chloroacridine derivative (Neidle, 1982), a 9-chloroacridine iodine complex (Rimmer et al., 2000), two solvates of 9-chloroacridine derivatives (Toma et al., 1993; Ojida et al., 2006) and the salt-type compound containing the 9-chloroacridinium cation (Ning et al., 1976). The crystal structures of these six compounds were found in the Cambridge Structural Database (Version 5.29; Allen, 2002). The C(9)–Cl, N(10)–C(12) and N(10)–C(14) bond lengths (in Å) in them vary from 1.719 to 1.748, from 1.332 to 1.375 and from 1.349 to 1.383, respectively. The corresponding values for the compound investigated (1.723, 1.346 and 1.351) thus fall well within the ranges found for other 9-chloroacridines.

In the crystal structure, N–H···O (Aakeröy et. al., 1992) and C–H···O (Steiner, 1999; Bianchi et al., 2004) hydrogen bonds link cations and anions in ion pairs (Table 1, Fig. 1). Inversely oriented ion pairs form stacks via π-π contacts of an attractive nature (Hunter et al., 2001), involving the central ring (Cg1) and the aromatic rings (Cg2 and Cg3) (Table 2), as well as C–H···O interactions between adjacent ions (Fig. 2). Stacks arranged in parallel are linked through intermolecular C–H···O interactions (Figs 2 and 3) to form layers (Fig. 3). The crystal structure is stabilized by short-range non-specific dispersive interactions between inversely oriented layers (Fig. 3) as well as by long-range electrostatic interactions between ions.

Related literature top

For general background, see: Acheson (1973); Demeunynck et al. (2001); Wróblewska et al. (2004); Zomer & Jacquemijns (2001). For related structures, see: Achari & Neidle (1977); Neidle (1982); Ning et al. (1976); Ojida et al. (2006); Rimmer et al. (2000); Toma et al. (1993). For intermolecular interactions, see: Aakeröy et al. (1992); Bianchi et al. (2004); Hunter et al. (2001); Steiner (1999). For the synthesis, see: Acheson (1973); Sato (1996). For a description of the Cambridge Structural Database, see: Allen (2002).

Experimental top

9-Chloro-2,4-dimethoxyacridine was prepared by heating 2-[(2,4-dimethoxyphenyl)amino]benzoic acid, obtained as described elsewhere (Acheson, 1973), with a sevenfold molar excess of POCl3 (400 K, 3 h). The excess POCl3 was subsequently removed under reduced pressure. The residue was dispersed in CHCl3, stirred in the presence of a mixture of ice and aqueous ammonia, separated by filtration and dried. The crude product was purified chromatographically (neutral Al2O3, CHCl3/toluene, 1/1 v/v, Rf=0.29). The 9-chloro-2,4-dimethoxyacridine was dissolved in CH2Cl2, then treated with a fivefold molal excess of methyl trifluoromethanesulfonate dissolved in the same solvent (under an Ar atmosphere at room temperature for 3 h) (Sato, 1996). The crude salt was dissolved in a small amount of ethanol, filtered and precipitated with a 25 v/v excess of diethyl ether (yield: 71%). Purple crystals suitable for X-ray investigations were grown from 2-propanol solution (m.p. 493–496 K).

Refinement top

H atoms were positioned geometrically, with C—H = 0.93 and 0.96 Å for the aromatic and methyl H atoms, respectively, and constrained to ride on their parent atoms with Uiso(H) = xUeq(C), where x = 1.2 for the aromatic and x = 1.5 for the methyl H atoms.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2008); cell refinement: CrysAlis RED (Oxford Diffraction, 2008); data reduction: CrysAlis RED (Oxford Diffraction, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound showing the atom-labeling scheme. Displacement ellipsoids are drawn at the 25% probability level and H atoms are shown as small spheres of arbitrary radius. The C5–H5···O23, N10–H10···O23 and C18–H18A···O22 hydrogen bonds are represented by dashed lines. Cg1, Cg2 and Cg3 denote the ring centroids.
[Figure 2] Fig. 2. The arrangement of the ions in the crystal structure, viewed along the a axis. The N–H···O and C–H···O hydrogen bonds are represented by dashed lines, the π-π contacts by dotted lines. H atoms not involved in interactions have been omitted. [Symmetry codes: (i) x + 1, y, z + 1; (ii) x, -y + 3/2, z + 1/2; (iii) x, -y + 3/2, z - 1/2.]
[Figure 3] Fig. 3. Ion pair stacks in the crystal structure, viewed along the c axis. The N–H···O and C–H···O interactions are represented by dashed lines. H atoms not involved in interactions have been omitted.
9-Chloro-2,4-dimethoxyacridinium trifluoromethanesulfonate top
Crystal data top
C15H13ClNO2+·CF3SO3−F(000) = 864
Mr = 423.79Dx = 1.625 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 5776 reflections
a = 11.0502 (9) Åθ = 3.0–29.2°
b = 23.110 (2) ŵ = 0.40 mm−1
c = 7.1435 (8) ÅT = 295 K
β = 108.214 (11)°Plate, purple
V = 1732.8 (3) Å30.60 × 0.20 × 0.10 mm
Z = 4
Data collection top
Oxford Diffraction Gemini R Ultra Ruby CCD
diffractometer		3072 independent reflections
Radiation source: Enhance (Mo) X-ray Source1932 reflections with I > 2σ(I)
graphiteRint = 0.063
Detector resolution: 10.4002 pixels mm-1θmax = 25.1°, θmin = 3.1°
ω scansh = −13→13
Absorption correction: multi-scan
(CrysAlis RED; Oxford Diffraction, 2008)		k = −25→27
Tmin = 0.782, Tmax = 0.959l = −8→8
12548 measured reflections
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)] = 0.058Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.179H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.1062P)2P]
where P = (Fo2 + 2Fc2)/3
3072 reflections(Δ/σ)max < 0.001
246 parametersΔρmax = 0.41 e Å−3
0 restraintsΔρmin = −0.28 e Å−3
Crystal data top
C15H13ClNO2+·CF3SO3−V = 1732.8 (3) Å3
Mr = 423.79Z = 4
Monoclinic, P21/cMo Kα radiation
a = 11.0502 (9) ŵ = 0.40 mm−1
b = 23.110 (2) ÅT = 295 K
c = 7.1435 (8) Å0.60 × 0.20 × 0.10 mm
β = 108.214 (11)°
Data collection top
Oxford Diffraction Gemini R Ultra Ruby CCD
diffractometer		3072 independent reflections
Absorption correction: multi-scan
(CrysAlis RED; Oxford Diffraction, 2008)		1932 reflections with I > 2σ(I)
Tmin = 0.782, Tmax = 0.959Rint = 0.063
12548 measured reflectionsθmax = 25.1°
Refinement top
R[F2 > 2σ(F2)] = 0.058H-atom parameters constrained
wR(F2) = 0.179Δρmax = 0.41 e Å−3
S = 1.06Δρmin = −0.28 e Å−3
3072 reflectionsAbsolute structure: ?
246 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C11.1372 (3)0.84277 (15)0.6837 (5)0.0588 (9)
H11.21520.86040.74470.071*
C21.0316 (3)0.87560 (16)0.6029 (5)0.0630 (9)
C30.9120 (3)0.85005 (15)0.5039 (5)0.0606 (9)
H30.84140.87340.44780.073*
C40.9004 (3)0.79165 (14)0.4907 (5)0.0539 (8)
C51.0717 (4)0.60054 (16)0.6391 (5)0.0672 (9)
H50.99050.58570.58020.081*
C61.1712 (4)0.56449 (18)0.7170 (6)0.0774 (11)
H61.15780.52470.71030.093*
C71.2939 (4)0.5859 (2)0.8075 (6)0.0824 (12)
H71.36080.56030.85950.099*
C81.3169 (4)0.64432 (19)0.8204 (6)0.0740 (10)
H81.39900.65790.88120.089*
C91.2292 (3)0.74378 (17)0.7518 (5)0.0586 (9)
N100.9955 (2)0.69822 (11)0.5708 (4)0.0525 (7)
H100.92130.68400.51280.063*
C111.1281 (3)0.78210 (15)0.6748 (4)0.0532 (8)
C121.0075 (3)0.75623 (14)0.5787 (4)0.0507 (8)
C131.2163 (3)0.68400 (16)0.7418 (5)0.0606 (9)
C141.0924 (3)0.66091 (15)0.6481 (4)0.0552 (8)
O151.0275 (2)0.93401 (11)0.6023 (4)0.0789 (8)
C161.1437 (4)0.96502 (17)0.6957 (6)0.0822 (11)
H16A1.12611.00570.69330.123*
H16B1.20380.95770.62630.123*
H16C1.17870.95230.82980.123*
O170.7946 (2)0.76076 (10)0.3978 (4)0.0661 (7)
C180.6815 (3)0.79154 (16)0.2905 (6)0.0708 (10)
H18A0.61460.76440.23130.106*
H18B0.69850.81450.18940.106*
H18C0.65570.81640.37890.106*
Cl191.37790 (8)0.77318 (5)0.86037 (16)0.0835 (4)
S200.67506 (9)0.60826 (4)0.27655 (15)0.0686 (4)
O210.7046 (4)0.56795 (15)0.1495 (6)0.1301 (14)
O220.5948 (3)0.65462 (13)0.1825 (5)0.1074 (11)
O230.7793 (2)0.62580 (14)0.4408 (5)0.0967 (9)
C240.5785 (4)0.56702 (17)0.3904 (6)0.0738 (10)
F250.6355 (3)0.52276 (13)0.4837 (5)0.1314 (12)
F260.5357 (4)0.59810 (14)0.5057 (6)0.1486 (14)
F270.4759 (3)0.54695 (15)0.2592 (5)0.1493 (14)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.054 (2)0.065 (2)0.0553 (19)−0.0088 (16)0.0140 (17)−0.0015 (16)
C20.063 (2)0.063 (2)0.065 (2)−0.0052 (18)0.0233 (19)0.0038 (17)
C30.052 (2)0.060 (2)0.069 (2)0.0021 (16)0.0174 (17)0.0038 (16)
C40.0440 (19)0.060 (2)0.0566 (19)0.0002 (15)0.0145 (16)0.0040 (15)
C50.063 (2)0.068 (2)0.066 (2)0.0039 (18)0.0139 (18)0.0018 (18)
C60.085 (3)0.068 (2)0.075 (2)0.021 (2)0.019 (2)0.004 (2)
C70.069 (3)0.091 (3)0.078 (3)0.027 (2)0.010 (2)0.001 (2)
C80.054 (2)0.092 (3)0.068 (2)0.016 (2)0.0068 (18)0.002 (2)
C90.0459 (19)0.079 (2)0.0499 (19)−0.0051 (17)0.0143 (16)−0.0011 (16)
N100.0432 (15)0.0611 (17)0.0512 (15)−0.0001 (12)0.0117 (12)0.0015 (12)
C110.0461 (19)0.070 (2)0.0451 (17)0.0013 (16)0.0166 (15)0.0014 (15)
C120.048 (2)0.061 (2)0.0460 (17)0.0001 (15)0.0194 (15)−0.0001 (14)
C130.047 (2)0.083 (3)0.0505 (19)0.0091 (17)0.0132 (16)0.0031 (17)
C140.052 (2)0.065 (2)0.0497 (18)0.0068 (16)0.0174 (16)0.0027 (16)
O150.0707 (17)0.0567 (15)0.1022 (19)−0.0073 (13)0.0168 (15)−0.0006 (13)
C160.082 (3)0.067 (2)0.087 (3)−0.022 (2)0.011 (2)−0.002 (2)
O170.0444 (14)0.0601 (14)0.0823 (17)−0.0032 (11)0.0030 (12)0.0067 (12)
C180.045 (2)0.071 (2)0.086 (3)0.0088 (17)0.0050 (19)0.0042 (19)
Cl190.0457 (6)0.1037 (8)0.0908 (7)−0.0074 (5)0.0067 (5)−0.0076 (6)
S200.0630 (6)0.0553 (6)0.0846 (7)−0.0041 (4)0.0190 (5)0.0067 (5)
O210.186 (4)0.090 (2)0.156 (3)−0.022 (2)0.114 (3)−0.022 (2)
O220.082 (2)0.0794 (19)0.138 (3)−0.0040 (16)0.0005 (19)0.0429 (18)
O230.0595 (16)0.099 (2)0.115 (2)−0.0209 (16)0.0038 (16)0.0111 (18)
C240.063 (2)0.066 (2)0.089 (3)−0.001 (2)0.021 (2)0.005 (2)
F250.112 (2)0.109 (2)0.178 (3)0.0179 (17)0.052 (2)0.080 (2)
F260.165 (3)0.122 (2)0.210 (4)−0.025 (2)0.132 (3)−0.023 (2)
F270.111 (2)0.174 (3)0.136 (3)−0.081 (2)−0.001 (2)0.033 (2)
Geometric parameters (Å, °) top
C1—C21.360 (5)N10—C121.346 (4)
C1—C111.405 (5)N10—C141.351 (4)
C1—H10.9300N10—H100.8600
C2—O151.351 (4)C11—C121.426 (4)
C2—C31.418 (5)C13—C141.427 (5)
C3—C41.356 (5)O15—C161.439 (4)
C3—H30.9300C16—H16A0.9600
C4—O171.354 (4)C16—H16B0.9600
C4—C121.414 (4)C16—H16C0.9600
C5—C61.353 (5)O17—C181.434 (4)
C5—C141.412 (5)C18—H18A0.9600
C5—H50.9300C18—H18B0.9600
C6—C71.398 (6)C18—H18C0.9600
C6—H60.9300S20—O211.408 (3)
C7—C81.370 (6)S20—O221.419 (3)
C7—H70.9300S20—O231.422 (3)
C8—C131.415 (5)S20—C241.803 (4)
C8—H80.9300C24—F251.275 (4)
C9—C131.388 (5)C24—F261.289 (4)
C9—C111.396 (5)C24—F271.310 (5)
C9—Cl191.723 (3)
C2—C1—C11119.9 (3)N10—C12—C11120.2 (3)
C2—C1—H1120.1C4—C12—C11119.8 (3)
C11—C1—H1120.1C9—C13—C8124.7 (3)
O15—C2—C1125.6 (3)C9—C13—C14117.7 (3)
O15—C2—C3112.9 (3)C8—C13—C14117.6 (4)
C1—C2—C3121.4 (3)N10—C14—C5121.1 (3)
C4—C3—C2120.1 (3)N10—C14—C13118.3 (3)
C4—C3—H3119.9C5—C14—C13120.6 (3)
C2—C3—H3119.9C2—O15—C16118.2 (3)
O17—C4—C3127.4 (3)O15—C16—H16A109.5
O17—C4—C12112.8 (3)O15—C16—H16B109.5
C3—C4—C12119.9 (3)H16A—C16—H16B109.5
C6—C5—C14119.4 (4)O15—C16—H16C109.5
C6—C5—H5120.3H16A—C16—H16C109.5
C14—C5—H5120.3H16B—C16—H16C109.5
C5—C6—C7121.2 (4)C4—O17—C18118.4 (3)
C5—C6—H6119.4O17—C18—H18A109.5
C7—C6—H6119.4O17—C18—H18B109.5
C8—C7—C6120.9 (4)H18A—C18—H18B109.5
C8—C7—H7119.6O17—C18—H18C109.5
C6—C7—H7119.6H18A—C18—H18C109.5
C7—C8—C13120.4 (4)H18B—C18—H18C109.5
C7—C8—H8119.8O21—S20—O22115.5 (2)
C13—C8—H8119.8O21—S20—O23115.4 (2)
C13—C9—C11123.7 (3)O22—S20—O23113.59 (19)
C13—C9—Cl19118.9 (3)O21—S20—C24103.3 (2)
C11—C9—Cl19117.4 (3)O22—S20—C24104.03 (19)
C12—N10—C14124.3 (3)O23—S20—C24102.66 (19)
C12—N10—H10117.9F25—C24—F26109.4 (4)
C14—N10—H10117.9F25—C24—F27105.4 (4)
C9—C11—C1125.3 (3)F26—C24—F27104.2 (4)
C9—C11—C12115.8 (3)F25—C24—S20113.3 (3)
C1—C11—C12118.8 (3)F26—C24—S20112.4 (3)
N10—C12—C4120.0 (3)F27—C24—S20111.5 (3)
C11—C1—C2—O15179.7 (3)Cl19—C9—C13—C82.0 (5)
C11—C1—C2—C3−1.8 (5)C11—C9—C13—C14−0.3 (5)
O15—C2—C3—C4179.7 (3)Cl19—C9—C13—C14−179.0 (2)
C1—C2—C3—C41.1 (5)C7—C8—C13—C9178.3 (3)
C2—C3—C4—O17−178.2 (3)C7—C8—C13—C14−0.7 (5)
C2—C3—C4—C121.0 (5)C12—N10—C14—C5178.1 (3)
C14—C5—C6—C70.5 (6)C12—N10—C14—C13−1.1 (4)
C5—C6—C7—C80.2 (6)C6—C5—C14—N10179.6 (3)
C6—C7—C8—C13−0.1 (6)C6—C5—C14—C13−1.2 (5)
C13—C9—C11—C1179.4 (3)C9—C13—C14—N101.5 (4)
Cl19—C9—C11—C1−2.0 (4)C8—C13—C14—N10−179.5 (3)
C13—C9—C11—C12−1.2 (4)C9—C13—C14—C5−177.7 (3)
Cl19—C9—C11—C12177.4 (2)C8—C13—C14—C51.3 (5)
C2—C1—C11—C9180.0 (3)C1—C2—O15—C16−0.5 (5)
C2—C1—C11—C120.6 (5)C3—C2—O15—C16−179.0 (3)
C14—N10—C12—C4179.1 (3)C3—C4—O17—C183.6 (5)
C14—N10—C12—C11−0.6 (4)C12—C4—O17—C18−175.7 (3)
O17—C4—C12—N10−2.6 (4)O21—S20—C24—F2559.0 (4)
C3—C4—C12—N10178.1 (3)O22—S20—C24—F25−180.0 (3)
O17—C4—C12—C11177.1 (3)O23—S20—C24—F25−61.4 (4)
C3—C4—C12—C11−2.2 (4)O21—S20—C24—F26−176.3 (4)
C9—C11—C12—N101.7 (4)O22—S20—C24—F26−55.3 (4)
C1—C11—C12—N10−178.9 (3)O23—S20—C24—F2663.3 (4)
C9—C11—C12—C4−178.0 (3)O21—S20—C24—F27−59.7 (4)
C1—C11—C12—C41.4 (4)O22—S20—C24—F2761.3 (4)
C11—C9—C13—C8−179.3 (3)O23—S20—C24—F27179.9 (3)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N10—H10···O230.862.012.826 (4)159
C5—H5···O230.932.423.151 (5)136
C8—H8···O22i0.932.533.348 (6)147
C18—H18A···O220.962.563.326 (5)137
C18—H18C···O22ii0.962.553.462 (5)158
Symmetry codes: (i) x+1, y, z+1; (ii) x, −y+3/2, z+1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N10—H10···O230.862.012.826 (4)159
C5—H5···O230.932.423.151 (5)136
C8—H8···O22i0.932.533.348 (6)147
C18—H18A···O220.962.563.326 (5)137
C18—H18C···O22ii0.962.553.462 (5)158
Symmetry codes: (i) x+1, y, z+1; (ii) x, −y+3/2, z+1/2.
Table 2
π–π Interactions (Å,°). top
CgICgJCg···CgDihedral angleInterplanar distance
11iii3.817 (2)0.333.506 (2)
11ii3.817 (2)0.333.499 (2)
12iii3.984 (2)1.193.484 (2)
12ii3.616 (2)1.193.493 (2)
23iii3.919 (2)1.953.490 (2)
32ii3.919 (2)1.953.509 (2)
Symmetry codes: (ii) x, -y+3/2, z+1/2; (iii) x, -y+3/2, z-1/2. Cg1, Cg2 and Cg3 are the centroids of the C9/N10/C11–C14, C1–C4/C11/C12 and C5–C8/C13/C14 rings, respectively. Cg···Cg is the distance between ring centroids. The dihedral angle is that between the planes of the rings. The interplanar distance is the perpendicular distance of CgI from ring J.
Acknowledgements top

The financing of this work from State Funds for Scientific Research (grant No. N204 123 32/3143, contract No. 3143/H03/2007/32, of the Polish Ministry of Research and Higher Education for the period 2007–2010) is acknowledged. BZ is grateful for a fellowship from the European Social Fund, the Polish State Budget and the Budget of the Province of Pomerania within the framework of the "Priority VIII Human Capital Operational Programme, action 8.2, subaction 8.2.2 'Regional Innovation Strategy'", of the 'InnoDoktorant' project of the Province of Pomerania - fellowships for PhD students, 1st edition.

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