Pyridine-4-carbaldehyde 4-phenylsemicarbazone

Mendoza-Meroño, R.; Menéndez-Taboada, L.; Fernández-Zapico, E.; García-Granda, S.

doi:10.1107/S1600536811013134

organic compounds

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ISSN: 2056-9890

Volume 67| Part 5| May 2011| Page o1135

doi:10.1107/S1600536811013134

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Pyridine-4-carbaldehyde 4-phenylsemicarbazone

Rafael Mendoza-Meroño,^a Laura Menéndez-Taboada,^a Eva Fernández-Zapico ^a and Santiago García-Granda ^a ^*

^aDepartamento de Química Física y Analítica, Facultad de Química, Universidad de Oviedo - CINN, C/ Julián Clavería, 8, 33006 Oviedo, Spain
^*Correspondence e-mail: sgg@uniovi.es

(Received 29 March 2011; accepted 7 April 2011; online 16 April 2011)

In the title compound, C₁₃H₁₂N₄O, the semicarbazone fragment links a benzene and a pyridine ring in the structure. The crystal packing is stabilized by strong intermolecular N—H⋯O hydrogen bonds, which connect two molecules to form a synthon unit, and by N—H⋯N hydrogen bonds and weak C—H⋯π interactions. The molecular conformation is stabilized by intramolecular N—H⋯N and C—H⋯O interactions.

Related literature

For related compounds and their biological activity, see: Pavan et al. (2010 ); Yogeeswari et al. (2005 ).

Experimental

Crystal data

C₁₃H₁₂N₄O
M_r = 240.27
Monoclinic, P 2₁ /c
a = 9.2794 (6) Å
b = 10.3384 (8) Å
c = 12.8244 (8) Å
β = 100.744 (6)°
V = 1208.73 (15) Å³
Z = 4
Cu Kα radiation
μ = 0.72 mm⁻¹
T = 295 K
0.30 × 0.11 × 0.06 mm

Data collection

Oxford Diffraction Xcalibur Gemini R diffractometer
Absorption correction: multi-scan (ABSPACK in CrysAlis PRO; Oxford Diffraction, 2010 $[Oxford Diffraction (2010). CrysAlis CCD, CrysAlis RED and CrysAlis PRO. Oxford Diffraction Ltd, Abingdon, England.]$ ) T_min = 0.888, T_max = 1.000
7257 measured reflections
2310 independent reflections
1702 reflections with I > 2σ(I)
R_int = 0.066

Refinement

R[F² > 2σ(F²)] = 0.052
wR(F²) = 0.143
S = 1.06
2310 reflections
176 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg2 is the centroid of the C8–C13 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N3—H3N⋯O1ⁱ	0.93 (2)	1.91 (2)	2.833 (2)	172 (2)
N4—H4N⋯N1ⁱⁱ	0.91 (2)	2.24 (2)	3.122 (3)	161.8 (19)
N4—H4N⋯N2	0.91 (2)	2.29 (2)	2.685 (2)	105.4 (16)
C13—H13⋯O1	0.93	2.31	2.854 (2)	117
C1—H1⋯Cg2ⁱⁱⁱ	0.93	2.88	3.644 (2)	140
Symmetry codes: (i) -x+1, -y, -z+2; (ii) -x+1, -y, -z+1; (iii) x+1, y, z.

Data collection: CrysAlis CCD (Oxford Diffraction, 2010 $[Oxford Diffraction (2010). CrysAlis CCD, CrysAlis RED and CrysAlis PRO. Oxford Diffraction Ltd, Abingdon, England.]$ ); cell refinement: CrysAlis RED (Oxford Diffraction, 2010 $[Oxford Diffraction (2010). CrysAlis CCD, CrysAlis RED and CrysAlis PRO. Oxford Diffraction Ltd, Abingdon, England.]$ ); data reduction: CrysAlis RED; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ) and Mercury (Macrae et al., 2008 ); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999 ), PLATON (Spek, 2009) and PARST95 (Nardelli, 1995 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811013134/fy2007sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811013134/fy2007Isup2.hkl

checkCIF report

Comment top

Semicarbazones and their metal complexes are important classes of compounds which have long attracted attention owing to their remarkable biological and pharmacological properties, such as antibacterial, antiviral, antineoplastic and anti Mycobacterium tuberculosis activity (Pavan et al., 2010). Using the semicarbazone template (Yogeeswari et al., 2005), significant anticonvulsant potential was demonstrated in epilepsy models for aryl semicarbazones. In view of the importance of these compounds, a new semicarbazone (I) has been synthesized, and its crystal structure is reported here (Fig. 1).

The configuration of (I) is E with respect to the C6═N2 bond. The pyridine and benzene rings are conected by a semicarbazone fragment (C6/N2/N3/C7/O1/N4). The values of the dihedral angles between the aromatic rings and the semicarbazone fragnent are 23.99 (7)° and 42.15 (7)° for the benzene and pyridine rings, respectively. This indicates the lack of planarity.

The crystal packing is stabilized by a pair of strong intermolecular N—H···O hydrogen bonds conecting two molecules to form a centrosymmtric unit (synthon), and by an N—H···N hydrogen bond (Fig. 2), which extends the packing along the c axis (Fig 3). The crystal is also stabilized by intermolecular C—H···π interactions (Fig. 4). This type of interaction affects the conformation of the molecule, specifically the torsion angle between the benzene ring and the semicarbazone moeity. The molecular conformation is stabilized by intramolecular N4—H4N···N2 and C13—H13···O1 interactions (Table 1).

From the centroid–centroid distance between two pyridine rings [4.0085 (2)Å] and the angle between the normal of the aromatic plane and the centroid–centroid vector [35.13 (5)°], we conclude that there is no significant π-π stacking interaction between the pyridine rings.

Related literature top

For related compounds and their biological activity, see: Pavan et al. (2010); Yogeeswari et al. (2005).

Experimental top

A solution of 4-pyridine carboxaldehyde (1.0711 g, 0.01 mol) and 4-phenylsemicarbazide (1.5117 g, 0.01 mol) in absolute methanol (50 ml) was refluxed for 4 h in the presence of p-toluenesulfonic acid as catalyst, with continuous stirring. On cooling to room temperature the precipitate was filtered off, washed with copious cold methanol and dried in air (m.p. 493.15 K). White single crystals of compound (I) were obtained after recrystallization from a solution in methanol.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2010); cell refinement: CrysAlis RED (Oxford Diffraction, 2010); data reduction: CrysAlis RED (Oxford Diffraction, 2010); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2008); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999), PLATON (Spek, 2009) and PARST95 (Nardelli, 1995).

Figures top

	Fig. 1. A view of the molecular structure of the title molecule showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.
	Fig. 2. Part of the crystal packing showing the principal intermolecular and intramolecular hydrogen bonds. Displacement ellipsoids are drawn at the 50% probability level. H atoms not involved in hydrogen bonding have been omitted for clarity.
	Fig. 3. Packing diagram viewed along the c axis. Hydrogen bonds are indicated by dashed lines.
	Fig. 4. Intermolecular C—H···π interactions along ac plane. H atoms not involved in hydrogen bonding have been omitted for clarity.

Pyridine-4-carbaldehyde 4-phenylsemicarbazone top

Crystal data top

C₁₃H₁₂N₄O	F(000) = 504
M_r = 240.27	D_x = 1.320 Mg m⁻³
Monoclinic, P2₁/c	Melting point: 493.15 K
Hall symbol: -P 2ybc	Cu Kα radiation, λ = 1.54180 Å
a = 9.2794 (6) Å	Cell parameters from 2114 reflections
b = 10.3384 (8) Å	θ = 3.5–70.7°
c = 12.8244 (8) Å	µ = 0.72 mm⁻¹
β = 100.744 (6)°	T = 295 K
V = 1208.73 (15) Å³	Rod, white
Z = 4	0.30 × 0.11 × 0.06 mm

Data collection top

Oxford Diffraction Xcalibur Gemini R diffractometer	2310 independent reflections
Radiation source: Enhance (Cu) X-ray Source	1702 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.066
Detector resolution: 10.2673 pixels mm^-1	θ_max = 70.8°, θ_min = 4.9°
ω scans	h = −10→11
Absorption correction: multi-scan (ABSPACK in CrysAlis PRO; Oxford Diffraction, 2010)	k = −12→11
T_min = 0.888, T_max = 1.000	l = −15→15
7257 measured reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.052	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.143	w = 1/[σ²(F_o²) + (0.0648P)² + 0.0647P] where P = (F_o² + 2F_c²)/3
S = 1.06	(Δ/σ)_max < 0.001
2310 reflections	Δρ_max = 0.20 e Å⁻³
176 parameters	Δρ_min = −0.17 e Å⁻³
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0051 (8)

Crystal data top

C₁₃H₁₂N₄O	V = 1208.73 (15) Å³
M_r = 240.27	Z = 4
Monoclinic, P2₁/c	Cu Kα radiation
a = 9.2794 (6) Å	µ = 0.72 mm⁻¹
b = 10.3384 (8) Å	T = 295 K
c = 12.8244 (8) Å	0.30 × 0.11 × 0.06 mm
β = 100.744 (6)°

Data collection top

Oxford Diffraction Xcalibur Gemini R diffractometer	2310 independent reflections
Absorption correction: multi-scan (ABSPACK in CrysAlis PRO; Oxford Diffraction, 2010)	1702 reflections with I > 2σ(I)
T_min = 0.888, T_max = 1.000	R_int = 0.066
7257 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.052	0 restraints
wR(F²) = 0.143	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	Δρ_max = 0.20 e Å⁻³
2310 reflections	Δρ_min = −0.17 e Å⁻³
176 parameters

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.31018 (14)	0.04113 (16)	0.96710 (10)	0.0562 (4)
N2	0.47959 (17)	−0.03751 (17)	0.75432 (12)	0.0474 (4)
N3	0.45910 (18)	−0.01377 (19)	0.85540 (13)	0.0524 (5)
N4	0.23363 (17)	0.07764 (18)	0.78923 (13)	0.0478 (4)
N1	0.7010 (2)	−0.1407 (2)	0.43544 (14)	0.0619 (5)
C7	0.3301 (2)	0.0358 (2)	0.87508 (14)	0.0443 (5)
C4	0.5324 (2)	−0.1475 (2)	0.55575 (16)	0.0505 (5)
H4	0.4383	−0.1666	0.5665	0.061*
C3	0.5689 (2)	−0.1643 (2)	0.45723 (16)	0.0557 (5)
H3	0.4964	−0.1940	0.4024	0.067*
C8	0.0926 (2)	0.1288 (2)	0.79070 (15)	0.0467 (5)
C5	0.6378 (2)	−0.1016 (2)	0.63847 (15)	0.0466 (5)
C9	0.0279 (2)	0.2034 (2)	0.70528 (16)	0.0551 (5)
H9	0.0782	0.2193	0.6502	0.066*
C6	0.6074 (2)	−0.0739 (2)	0.74389 (16)	0.0489 (5)
C13	0.0161 (2)	0.1054 (2)	0.87145 (16)	0.0575 (6)
H13	0.0572	0.0541	0.9289	0.069*
C10	−0.1102 (3)	0.2545 (3)	0.70086 (19)	0.0672 (7)
H10	−0.1528	0.3038	0.6425	0.081*
C2	0.8014 (2)	−0.0989 (3)	0.51620 (18)	0.0657 (6)
H2	0.8949	−0.0817	0.5034	0.079*
C1	0.7765 (2)	−0.0794 (2)	0.61736 (17)	0.0571 (6)
H1	0.8519	−0.0516	0.6709	0.069*
C12	−0.1218 (2)	0.1586 (3)	0.86654 (19)	0.0687 (7)
H12	−0.1722	0.1434	0.9216	0.082*
C11	−0.1858 (3)	0.2335 (3)	0.7820 (2)	0.0712 (7)
H11	−0.2783	0.2692	0.7796	0.085*
H6	0.686 (2)	−0.083 (2)	0.8069 (17)	0.058 (6)*
H3N	0.533 (3)	−0.031 (2)	0.9132 (19)	0.065 (7)*
H4N	0.266 (2)	0.080 (2)	0.7265 (18)	0.053 (6)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0482 (8)	0.0824 (11)	0.0385 (7)	0.0050 (7)	0.0096 (6)	−0.0017 (7)
N2	0.0489 (9)	0.0571 (10)	0.0367 (8)	0.0029 (7)	0.0089 (7)	−0.0020 (7)
N3	0.0444 (9)	0.0765 (13)	0.0358 (8)	0.0107 (8)	0.0066 (7)	−0.0017 (8)
N4	0.0439 (9)	0.0619 (11)	0.0388 (8)	0.0066 (7)	0.0110 (7)	0.0011 (7)
N1	0.0681 (12)	0.0707 (13)	0.0507 (10)	0.0103 (9)	0.0212 (9)	0.0032 (9)
C7	0.0430 (10)	0.0525 (12)	0.0373 (10)	−0.0012 (8)	0.0076 (7)	−0.0035 (8)
C4	0.0517 (11)	0.0529 (12)	0.0482 (11)	0.0021 (9)	0.0124 (9)	−0.0005 (9)
C3	0.0614 (13)	0.0577 (14)	0.0473 (12)	0.0047 (10)	0.0081 (9)	−0.0026 (9)
C8	0.0447 (10)	0.0521 (12)	0.0437 (10)	0.0019 (8)	0.0092 (8)	−0.0038 (8)
C5	0.0484 (10)	0.0497 (12)	0.0423 (10)	0.0084 (8)	0.0103 (8)	0.0044 (8)
C9	0.0580 (12)	0.0613 (14)	0.0472 (11)	0.0101 (10)	0.0127 (9)	0.0036 (10)
C6	0.0430 (10)	0.0603 (13)	0.0428 (10)	0.0061 (9)	0.0065 (8)	0.0024 (9)
C13	0.0521 (11)	0.0751 (16)	0.0479 (11)	0.0077 (10)	0.0159 (9)	0.0106 (10)
C10	0.0679 (14)	0.0759 (17)	0.0579 (14)	0.0233 (11)	0.0116 (11)	0.0102 (11)
C2	0.0568 (13)	0.0857 (18)	0.0597 (13)	0.0021 (11)	0.0239 (11)	0.0007 (12)
C1	0.0464 (11)	0.0726 (15)	0.0530 (12)	0.0040 (10)	0.0105 (9)	−0.0012 (10)
C12	0.0568 (13)	0.0924 (19)	0.0611 (14)	0.0139 (12)	0.0219 (10)	0.0058 (13)
C11	0.0586 (14)	0.0851 (19)	0.0725 (16)	0.0239 (12)	0.0193 (12)	0.0045 (13)

Geometric parameters (Å, º) top

O1—C7	1.229 (2)	C8—C9	1.382 (3)
N2—C6	1.275 (2)	C5—C1	1.383 (3)
N2—N3	1.367 (2)	C5—C6	1.460 (3)
N3—N2	1.367 (2)	C9—C10	1.378 (3)
N3—C7	1.368 (2)	C9—H9	0.9300
N3—H3N	0.93 (2)	C6—H6	0.99 (2)
N4—C7	1.354 (2)	C13—C12	1.384 (3)
N4—C8	1.415 (2)	C13—H13	0.9300
N4—H4N	0.91 (2)	C10—C11	1.376 (3)
N1—C3	1.329 (3)	C10—H10	0.9300
N1—C2	1.329 (3)	C2—C1	1.374 (3)
C4—C3	1.379 (3)	C2—H2	0.9300
C4—C5	1.386 (3)	C1—H1	0.9300
C4—H4	0.9300	C12—C11	1.373 (3)
C3—H3	0.9300	C12—H12	0.9300
C8—C13	1.381 (3)	C11—H11	0.9300

C6—N2—N3	116.68 (16)	C10—C9—H9	119.7
N2—N3—C7	121.56 (16)	C8—C9—H9	119.7
N2—N3—H3N	120.5 (14)	N2—C6—C5	119.94 (17)
C7—N3—H3N	117.9 (14)	N2—C6—H6	120.3 (12)
C7—N4—C8	125.56 (16)	C5—C6—H6	119.8 (12)
C7—N4—H4N	116.7 (13)	C8—C13—C12	119.8 (2)
C8—N4—H4N	117.4 (13)	C8—C13—H13	120.1
C3—N1—C2	115.80 (18)	C12—C13—H13	120.1
O1—C7—N4	124.85 (17)	C11—C10—C9	120.6 (2)
O1—C7—N3	119.15 (17)	C11—C10—H10	119.7
N4—C7—N3	115.99 (16)	C9—C10—H10	119.7
C3—C4—C5	119.03 (19)	N1—C2—C1	124.5 (2)
C3—C4—H4	120.5	N1—C2—H2	117.7
N1—C3—C4	124.3 (2)	C1—C2—H2	117.7
N1—C3—H3	117.9	C2—C1—C5	119.1 (2)
C4—C3—H3	117.9	C2—C1—H1	120.4
C13—C8—C9	118.96 (18)	C5—C1—H1	120.4
C13—C8—N4	123.37 (18)	C11—C12—C13	121.3 (2)
C9—C8—N4	117.65 (18)	C11—C12—H12	119.3
C1—C5—C4	117.19 (18)	C13—C12—H12	119.3
C1—C5—C6	119.74 (18)	C12—C11—C10	118.7 (2)
C4—C5—C6	123.05 (18)	C12—C11—H11	120.7
C10—C9—C8	120.6 (2)	C10—C11—H11	120.7

C6—N2—N3—C7	174.5 (2)	N3—N2—C6—C5	179.75 (18)
C8—N4—C7—O1	−2.8 (3)	C1—C5—C6—N2	148.6 (2)
C8—N4—C7—N3	178.13 (19)	C4—C5—C6—N2	−30.0 (3)
N2—N3—C7—O1	171.39 (19)	C9—C8—C13—C12	−1.2 (3)
N2—N3—C7—N4	−9.5 (3)	N4—C8—C13—C12	−179.6 (2)
C2—N1—C3—C4	0.3 (3)	C8—C9—C10—C11	0.7 (4)
C5—C4—C3—N1	0.8 (3)	C3—N1—C2—C1	−0.1 (4)
C7—N4—C8—C13	−21.7 (3)	N1—C2—C1—C5	−1.3 (4)
C7—N4—C8—C9	159.8 (2)	C4—C5—C1—C2	2.3 (3)
C3—C4—C5—C1	−2.1 (3)	C6—C5—C1—C2	−176.3 (2)
C3—C4—C5—C6	176.49 (19)	C8—C13—C12—C11	0.8 (4)
C13—C8—C9—C10	0.4 (3)	C13—C12—C11—C10	0.3 (4)
N4—C8—C9—C10	179.0 (2)	C9—C10—C11—C12	−1.1 (4)

Hydrogen-bond geometry (Å, º) top

Cg2 is the centroid of the C8–C13 ring.

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3N···O1ⁱ	0.93 (2)	1.91 (2)	2.833 (2)	172 (2)
N4—H4N···N1ⁱⁱ	0.91 (2)	2.24 (2)	3.122 (3)	161.8 (19)
N4—H4N···N2	0.91 (2)	2.29 (2)	2.685 (2)	105.4 (16)
C13—H13···O1	0.93	2.31	2.854 (2)	117
C1—H1···Cg2ⁱⁱⁱ	0.93	2.88	3.644 (2)	140

Symmetry codes: (i) −x+1, −y, −z+2; (ii) −x+1, −y, −z+1; (iii) x+1, y, z.

Experimental details

Crystal data
Chemical formula	C₁₃H₁₂N₄O
M_r	240.27
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	295
a, b, c (Å)	9.2794 (6), 10.3384 (8), 12.8244 (8)
β (°)	100.744 (6)
V (Å³)	1208.73 (15)
Z	4
Radiation type	Cu Kα
µ (mm⁻¹)	0.72
Crystal size (mm)	0.30 × 0.11 × 0.06

Data collection
Diffractometer	Oxford Diffraction Xcalibur Gemini R diffractometer
Absorption correction	Multi-scan (ABSPACK in CrysAlis PRO; Oxford Diffraction, 2010)
T_min, T_max	0.888, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	7257, 2310, 1702
R_int	0.066
(sin θ/λ)_max (Å⁻¹)	0.613

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.052, 0.143, 1.06
No. of reflections	2310
No. of parameters	176
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.20, −0.17

Computer programs: CrysAlis CCD (Oxford Diffraction, 2010), CrysAlis RED (Oxford Diffraction, 2010), SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Macrae et al., 2008), WinGX publication routines (Farrugia, 1999), PLATON (Spek, 2009) and PARST95 (Nardelli, 1995).

Hydrogen-bond geometry (Å, º) top

Cg2 is the centroid of the C8–C13 ring.

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3N···O1ⁱ	0.93 (2)	1.91 (2)	2.833 (2)	172 (2)
N4—H4N···N1ⁱⁱ	0.91 (2)	2.24 (2)	3.122 (3)	161.8 (19)
N4—H4N···N2	0.91 (2)	2.29 (2)	2.685 (2)	105.4 (16)
C13—H13···O1	0.93	2.31	2.854 (2)	117
C1—H1···Cg2ⁱⁱⁱ	0.93	2.88	3.644 (2)	140

Symmetry codes: (i) −x+1, −y, −z+2; (ii) −x+1, −y, −z+1; (iii) x+1, y, z.

Acknowledgements

Financial support by the Agencia Española de Cooperación Internacional y Desarrollo (AECID), FEDER funding, the Spanish MICINN (MAT2006–01997, MAT2010-15094 and the Factoría de Cristalización Consolider Ingenio 2010), the Gobierno del Principado de Asturias (PCTI), the University of Oviedo and Banco Santander is acknowledged.

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