Michaela Fridrichová

Guanylurea(1+) hydrogen phosphite: a novel promising phase-matchable material for second harmonic generation

A novel and promising material, guanylurea(1+) hydrogen phosphite, which belongs to the group of inorganic salts of polarizable organic molecules was prepared. Its real potential for optical applications is based on the simplicity of synthesis, good ability to crystallize, transparency, thermal stability and efficiency of the second harmonic generation comparable to urea.

THE INVESTIGATION OF SECOND-ORDER NONLINEAR OPTICAL PROPERTIES OF P-NITROPHENYLAZOANILINE: SECOND HARMONIC GENERATION AND AB INITIO COMPUTATIONS

p-nitrophenylazoaniline (1) belongs to the family of compounds with conjugated bonds and delocalized π-electrons, structurally similar to the well known push-pull compound Disperse Red 1 (DR1).1 Due to the assembly of the molecule, nonlinear optical (NLO) properties are expectable and can be more or less accurately predicted. To estimate the potential for second-order NLO properties, the electric dipole moment (μ), dispersion-free dipole polarizabilities (α) and first hyperpolarizabilities (β) have been determined by density functional theory (DFT) quantum chemical calculations at B3LYP/ 6-311 + G(d, p) level. According to the computation results, the synthesized compound exhibits non-zero β values and it might have second-order NLO behavior. Title compound has been synthesized and characterized by FT-IR, 1H-NMR and UV-Vis spectroscopies. The maximum one-photon absorption (OPA) wavelengths were estimated to be shorter than 450 nm by quantum mechanical computations using the configuration interaction (CI) method. The same result was achieved by UV-Vis spectra measurements, whereas the compound exhibited good optical transparency to the visible light. Quantitative measurements of second harmonic generation (SHG) at 800 nm and 1064 nm have been performed. The relative efficiency comparable with that of KDP (kalium diphosphate) has been observed with the exciting wavelength of 1064 nm, while the other wavelength led to strong absorption of produced light by the sample. In the following more detailed study on frequency-dependent first hyperpolarizabilities using time-dependent Hartree–Fock (TDHF) method have been computed at the wavelengths used in SHG measurements.

Guanylurea(1+) hydrogen phosphite: study of linear and nonlinear optical properties

Linear and nonlinear optical properties of a spontaneously grown non-centrosymmetric crystal of guanylurea(1+) hydrogen phosphite (GUHP) were investigated. Optically negative biaxial crystals of GUHP exhibit a birefringence higher than calcite. Highly anisotropic refractive indices of GUHP and its nonlinear optical coefficients were determined. Phase matching of GUHP was described by an experimentally determined Hobden diagram. High and phase-matchable optical nonlinearities of GUHP together with its wide transparency range and an excellent resistance against optical damage approve its potential for applications in nonlinear optics.

Mixed crystals of 2-carbamoylguanidinium with hydrogen fluorophosphonate and hydrogen phosphite in the ratios 1:0, 0.76 (2):0.24 (2) and 0.115 (7):0.885 (7).

The title compounds, 2-carbamoylguanidinium hydrogen fluorophosphonate, C(2)H(7)N(4)O(+)·HFO(3)P(-), (I), 2-carbamoylguanidinium-hydrogen fluorophosphonate-hydrogen phosphite (1/0.76/0.24), C(2)H(7)N(4)O(+)·0.76HFO(3)P(-)·0.24H(2)O(3)P(-), (II), and 2-carbamoylguanidinium-hydrogen fluorophosphonate-hydrogen phosphite (1/0.115/0.885), C(2)H(7)N(4)O(+)·0.115HFO(3)P(-)·0.885H(2)O(3)P(-), (III), are isostructural with guanylurea hydrogen phosphite, C(2)H(7)N(4)O(+)·H(2)O(3)P(-) [Fridrichová, Němec, Císařová & Němec (2010). CrystEngComm, 12, 2054-2056]. They constitute structures where the hydrogen phosphite anion has been fully or partially replaced by hydrogen fluorophosphonate. The title structures are the fourth example of isostructural compounds which differ by the presence of hydrogen fluorophosphonate and hydrogen phosphite or fluorophosphonate and phosphite anions. Moreover, the present study reports structures with these mixed anions for the first time. In the reported mixed salts, the P and O atoms of either anion overlap almost exactly, as can be judged by comparison of their equivalent isotropic displacement parameters, while the P-F and P-H directions are almost parallel. There are strong O-H···O hydrogen bonds between the anions, as well as strong N-H···O hydrogen bonds between the 2-carbamoylguanidinium cations in the title structures. Altogether they form a three-dimensional hydrogen-bond pattern. Interestingly, rare N-H···F interactions are also present in the title structures. Another exceptional feature concerns the P-O(H) distances, which are about as long as the P-F distance. The dependence of P-F distances on the longest P-O distances in FO(3)P(2-) or HFO(3)P(-) is presented. The greater content of hydrogen phosphite in the mixed crystals causes a larger deformation of the cations from planarity.

Tris(2-carbamoylguanidinium) hydrogen fluoro­phospho­nate fluoro­phospho­nate monohydrate

The title structure, 3C2H7N4O+·HFPO3 −·FPO3 2−·H2O, contains three independent 2-carbamoylguanidinium cations, one fluorophosphonate, one hydrogen fluorophosphonate and one water molecule. There are three different layers in the structure that are nearly perpendicular to the c axis. Each layer contains a cation and the layers differ by the respective presence of the water molecule, the hydrogen fluorophosphonate and fluorophosphonate anions. N—H⋯O hydrogen bonds between the guanylurea molecules that interconnect the molecules within each layer are strong. The layers are interconnected by strong and weak O—H⋯O hydrogen bonds between the anions and water molecules, respectively. Interestingly, the configuration of the layers is quite similar to that observed in 2-carbamoylguanidinium hydrogen fluorophosphonate [Fábry et al. (2012). Acta Cryst. C68, o76–o83]. There is also present a N—H⋯F hydrogen bond in the structure which occurs quite rarely.

1,1-Dimethyl­biguanidium(2+) dinitrate

In the crystal structure of the title compound, C4H13N5 2+·2NO3 −, the main intermolecular interactions are the N—H⋯O hydrogen bonds between the cationic amino groups and the O atoms of the nitrate ions. All amino H atoms and nitrate O atoms are involved in the three-dimensional hydrogen-bond network. There are two graph-set motifs R 2 2(8), which include the amino groups connected to the N atoms in the biguanide 3-, 4- and 5-positions, and the O atoms of a nitrate ion. They are extended along the a axis. An O atom of the second nitrate ion is involved in a graph-set motif C(4) that is a part of a helix-like N—H⋯O⋯H—N—H⋯O⋯ chain oriented along the b axis. There are also two weak C—H⋯O interactions in the crystal structure.

Two polymorphs of bis(2-carbamoylguanidinium) fluorophosphonate dihydrate.

Two polymorphs of bis(2-carbamoylguanidinium) fluorophosphonate dihydrate, 2C(2)H(7)N(4)O(+)·FO(3)P(2-)·2H(2)O, are presented. Polymorph (I), crystallizing in the space group Pnma, is slightly less densely packed than polymorph (II), which crystallizes in Pbca. In (I), the fluorophosphonate anion is situated on a crystallographic mirror plane and the O atom of the water molecule is disordered over two positions, in contrast with its H atoms. The hydrogen-bond patterns in both polymorphs share similar features. There are O-H···O and N-H···O hydrogen bonds in both structures. The water molecules donate their H atoms to the O atoms of the fluorophosphonates exclusively. The water molecules and the fluorophosphonates participate in the formation of R(4)(4)(10) graph-set motifs. These motifs extend along the a axis in each structure. The water molecules are also acceptors of either one [in (I) and (II)] or two [in (II)] N-H···O hydrogen bonds. The water molecules are significant building elements in the formation of a three-dimensional hydrogen-bond network in both structures. Despite these similarities, there are substantial differences between the hydrogen-bond networks of (I) and (II). The N-H···O and O-H···O hydrogen bonds in (I) are stronger and weaker, respectively, than those in (II). Moreover, in (I), the shortest N-H···O hydrogen bonds are shorter than the shortest O-H···O hydrogen bonds, which is an unusual feature. The properties of the hydrogen-bond network in (II) can be related to an unusually long P-O bond length for an unhydrogenated fluorophosphonate anion that is present in this structure. In both structures, the N-H···F interactions are far weaker than the N-H···O hydrogen bonds. It follows from the structure analysis that (II) seems to be thermodynamically more stable than (I).

N-[Amino(imino)methyl]uronium tetrafluoroborate

In the title compound, C2H7N4O+·BF4 −, intermolecular N—H⋯O hydrogen bonds connect the cations into chains parallel to the c axis, with graph-set motif C(4). These chains are in turn connected into a three-dimensional network by intermolecular N—H⋯F hydrogen bonds. The B—F distances distances in the anion are not equal.