Maria G. Babashkina

FRET based tri-color emissive rhodamine–pyrene conjugate as an Al3+ selective colorimetric and fluorescence sensor for living cell imaging

A rhodamine-pyrene hybrid molecule acts as a colorimetric and fluorimetric sensor for Al(3+) through time dependent PET-CHEF and FRET processes associated with tri-color emission. Intracellular Al(3+) has been visualized through time dependent blue-green-red emission. The lowest limit of detection for Al(3+) is 0.02 μM.

The influence of the intramolecular hydrogen bond on the 1,3-N,S- and 1,5-O,S-coordination of N-phosphoryl-N′-(R)-thioureas with Ni(II) and Pd(II)

Reaction of the potassium salts of N-phosphorylated thioureas of common formula R1–N(H)–C(S)–N(H)–P(O)(OiPr)2 (HA) with NiII and PdII cations leads to [MA2] chelate complexes (M = NiII, R1 = p-MeOC6H4, p-BrC6H4, t-Bu, c-Hex; M = PdII, R = iPr). In both the NiII and PdII complexes, the metal center is found in a square-planar N2S2 environment formed by the CS sulfur atoms and the P–N nitrogen atoms of two deprotonated ligands A−. The PdII atoms in [PdB2] complexes with deprotonated thioureas of common formula R2–C(S)–N(H)–P(O)(OiPr)2 (HB) (R2 = Et2N, morpholine-N-yl) are coordinated in a square-planar fashion by the CS sulfur atoms and the PO oxygen atoms of two anionic ligands. Molecular structures of four complexes [M(A-N,S)2] (M = NiII, R1 = p-MeOC6H4, p-BrC6H4, t-Bu; M = PdII, R1 = iPr) and the palladium(II) 1,5-O,S-chelate of formula [Pd(B-O,S)2] (R2 = morpholine-N-yl) were elucidated by X-ray diffraction.

Competitive bulk liquid membrane transport of some metal ions using RC(S)NHP(S)(OiPr)2 as ionophores. Unusual supramolecular “honeycomb” aggregate of the polynuclear copper(I) complex of H2NC(S)NHP(S)(OiPr)2

Competitive transport experiments involving metal ions from an aqueous source phase through a chloroform membrane into an aqueous receiving phase have been carried out using a series of N-(thio)phosphorylated (thio)amide and thiourea ligands as ionophores in the organic phase. The source phase contained equimolar concentrations of Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Cd(II) and Pb(II) with the source and receiving phases being buffered at different pH. Good transport properties were observed for Ag(I) in the case of (13). The best extraction properties have been shown by (3)L(1), (3)L(8), (2)L(7), (3)L(9) and (3)L(11) which contain an unsubstituted nitrogen atom at the C[double bond, length as m-dash]S groups ((3)L(1) and (3)L(9)), or a third nitrogen atom, capable of participating in additional coordination ((3)L(8), (2)L(7) and (3)L(11)). Reaction of Cu(NO(3))(2).6H(2)O with the potassium salt of the N-thiophosphorylated thiourea NH(2)C(S)NHP(S)(OiPr)(2) formed a new supramolecular Cu(I) complex, [{Cu(6)((2)L(1))(6)}{Cu(3)((2)L(1))(3)}.4Me(2)CO] that contains both trinuclear and hexanuclear forms in its solid state structure, and in solution.

Competitive bulk liquid membrane transport and solvent extraction of some metal ions using RC(S)NHP(X)(OiPr)2 (X = O, S) as ionophores. Formation of the polynuclear complex of [Ag(NC–NP(S)(OiPr)2)]n

Competitive transport experiments involving metal ions from an aqueous source phase through a chloroform membrane into an aqueous receiving phase have been carried out using a series of N-(thio)phosphorylated (thio)amide and thiourea ligands as the ionophore present in the organic phase. The source phase contained equimolar concentrations of Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Cd(II) and Pb(II) with the source and receiving phases being buffered at a number of different pHs. Solvent extraction properties of the ligands towards the same metal cations under the same experimental conditions as for the transport were also studied. All ligands demonstrated 100% extraction of Ag(I). Reaction of AgNO(3) with the potassium salt of the N-thiophosphorylated thiourea NH(2)C(S)NHP(S)(OiPr)(2) gave a new supramolecular Ag(I) complex, [AgZ](n) (Z = {N[triple bond]C-NP(S)(OiPr)(2)}(-)) that contains both tri- and tetracoordinated Ag(I). The novel polynuclear Ag(I) complex [AgZ](n) described and structurally characterized by single crystal X-ray diffraction has no precedent.

Solvent-induced 1,3-N,S- vs. 1,5-S,S′-coordination in the NiII complex [Ni{p-Me2NC6H4NHC(S)NP(S)(OiPr)2}2]

Reaction of the deprotonated N-thiophosphorylated thiourea p-Me2NC6H4NHC(S)NHP(S)(OiPr)2 (HL) with NiCl2 leads to violet [Ni(L-1,3-N,S)2] or dark violet [Ni(L-1,5-S,S′)2]·(CH3)2CO crystals that were isolated by recrystallization from a mixture of CH2Cl2 or acetone, respectively, and n-hexane.

The influence of an intramolecular hydrogen bond on the 1,3-N,S-coordination of crown ether-containing N-phosphorylthiourea with NiII

Reaction of the lithium salt of N-phosphorylated thiourea [4′-benzo-15-crown-5]NHC(S)NHP(O)(OiPr)2 (HLI) with NiII leads to the chelate complex [NiLI2]. The metal center is found in a square-planar N2S2 environment formed by the CS sulfur atoms and the P–N nitrogen atoms of two deprotonated LI ligands. Reaction of [NiLI2] and its non-crown ether-containing analog Ni[PhNHC(S)NP(O)(OiPr)2]2 ([NiLII2]) with 2,2′-bipyridine (bipy) and 1,10-phenanthroline (phen) leads to the [Ni(bipy)LI,II2] and [Ni(phen)LI,II2] heteroligand complexes. The coordination mode is preserved for the phosphorus-containing ligands. The extraction properties of the crown ether-containing compounds towards alkali metal picrates were investigated. The molecular structures of HLI, [NiLI2] and [Ni(bipy)LII2] were elucidated by X-ray diffraction.

Mononuclear heteroleptic complexes of copper(I) with 5-phenyl-2,2′-bipyridine and triphenylphosphine: crystal structures, Hirshfeld surface analysis and luminescence properties

The reaction of 5-phenyl-2,2′-bipyridine (L) with a mixture of CuCl or CuBr and PPh3 leads to the formation of mononuclear heteroleptic complexes [CuL(PPh3)Cl] (1) and [CuL(PPh3)Br] (2). According to X-ray diffraction, 1 and 2 crystallize in the triclinic P and orthorhombic Pbca space groups, respectively. The structure of 1 contains four independent molecules in the asymmetric unit. Both structures reveal that each tetracoordinated copper(I) atom is linked to the two nitrogen atoms of L, one halogen and one PPh3 with the formation of a slightly distorted trigonal pyramidal coordination core. Both structures are additionally stabilized by weak intramolecular π⋯π stacking interactions formed between the terminal pyridine fragments of two ligands L corresponding to two adjacent molecules. Hirshfeld surface analysis showed that the structures of both complexes are highly dominated by H⋯H and H⋯C contacts and also characterized by H⋯Hal, C⋯C, H⋯N and C⋯N contacts. Both 1 and 2 were found to be emissive in the solid state at 298 K, with maxima at 596 and 610 nm, respectively, due to a (M + Hal)LCT excited state. The observed blue-shifting of the emission maximum of 1 and 2 compared to that of the previously reported [CuL(PPh3)I] can be explained by the replacement of the iodide by a weaker electron-donating bromide and chloride, respectively, lowering the HOMO energy level, less influencing the LUMO energy, and thus resulting in an increase of the HOMO–LUMO energy gap. This explanation is further supported by comparison with the recently reported emission maxima at 630 and 575 nm of the closely related complexes, namely [CuL(PPh3)I] and [CuL(PPh3)2]BF4, respectively. The emission maxima of 1, 2 and [CuL(PPh3)I] are slightly (12–16 nm) shifted to longer wavelengths when the temperature was lowered to 77 K.

Thiophosphorylated bis-thioureas for competitive bulk liquid membrane transport of some metal ions

Eight N-thiophosphorylated bis-thioureas of the common formula Z[NHC(S)NHP(S)(OiPr) 2] 2 [Z = (1), 1,2-C 6H 4 (2), 1,3-C 6H 4 (3), 1,4-C 6H 4 (4), CH 2(1,4-C 6H 4) 2 (5), O(1,4-C 6H 4) 2 (6), S(1,4-C 6H 4) 2 (7), CH 2(1,4-C 6H 10) 2 (8)] have been synthesized and characterized by NMR spectroscopy and elemental analysis. Molecular structures of 3, 4, 5·0.5C 6H 14, 6·CH 2Cl 2 and 8 were elucidated by X-ray diffraction revealing two linear intramolecular hydrogen bonds. Their crystal structures are stabilized by four intermolecular hydrogen bonds, which in turn lead to a polymeric chain formation. Competitive transport experiments involving metal ions from an aqueous source phase through a chloroform membrane into an aqueous receiving phase have been carried out using 1-8 as the ionophore present in the organic phase.

Detailed studies of the interaction of 3-chloroaniline with O,O′-diphenylphosphorylisothiocyanate

The reaction of neat 3-chloroaniline with neat SCN–P(O)(OPh)2 leads to a new N-phosphorylated thiourea, 3-ClC6H4NHC(S)NHP(O)(OPh)2 (1). The same reaction in non-dried CH2Cl2 or C6H6 leads to the salt-like compounds [3-ClC6H4NH3]+[NCS]− (2) and [3-ClC6H4NH3]+[P(O)2(OPh)2]−·0.5C6H6 (3·0.5C6H6), respectively, while using non-dried acetone yields 1-(3-chlorophenyl)-4,4,6-trimethyl-3,4-dihydropyrimidine-2(1H)-thione (4). Dissolution of 1 in non-dried CH2Cl2, C6H6 or Me2CO leads to the direct formation of 2, 3·0.5C6H6 and 4, respectively. It was established that thione 4 is most likely formed through the thiourea 1-assisted aldol condensation of acetone leading to mesityl oxide. In turn the latter ketone interacts with 1 followed by its hydrolysis leading to 4. Compounds 1–4 have been characterized by NMR spectroscopy and elemental analysis and their molecular structures were elucidated by X-ray diffraction. Hirshfeld surface analysis showed that the structures of both 1 and 4 are mainly characterized by H⋯H, H⋯C, H⋯Cl and H⋯S contacts as well as by H⋯O in the structure of 1. The enrichment ratio, derived as the decomposition of the crystal contact surface between pairs of interacting chemical species, for 1 was found, as expected for the polar contacts, which are generally hydrogen bonds, to be significantly larger than unity for the contacts of the type H⋯O and H⋯S. A much larger than unity value was found for the enrichment ratio of the C⋯C contacts in the structure of 1, which is due to extensive π⋯π stacking in the crystal packing. The enrichment ratio for 4 was found to be larger than unity for the contacts of the type H⋯C and, but with a lesser degree, H⋯Cl and H⋯S.

N-Salicylidene aniline derivatives based on the N′-thiophosphorylated thiourea scaffold

A new family of N′-thiophosphorylated thiourea-containing N-salicylidene aniline derivatives (anils) of the common formula 6-{(2-OH-aryl)–CHN}-Py-2-NHC(S)NHP(S)(OiPr)2 [aryl = C6H4 (2), 5-Cl–C6H3 (3), 5-Br–C6H3 (4), 3,5-Cl2–C6H2 (5), or 3,5-Br2–C6H2 (6)] has been synthesized by the condensation of N-thiophosphorylated thiourea 6-NH2-Py-2-NHC(S)NHP(S)(OiPr)2 (1) with the corresponding salicylaldehyde. Compound 2 was obtained by dissolving 1 in pure salicylaldehyde, while anils 3–6 were synthesized in EtOH. Synthesis in EtOH with aniline led to X-ray suitable crystals of 1, in which the crystal structure was challenging so far. All compounds were characterized by elemental analysis, NMR, diffuse reflectance and fluorescence spectroscopy. The crystal structures of 2–6, elucidated by X-ray diffraction, are stabilized by two intra- and two intermolecular hydrogen bonds and a broad network of intermolecular π⋯π stacking interactions. Compounds 2 and 6 trapped salicylaldehyde and ethanol molecules, respectively, in their crystal structures through the formation of intermolecular hydrogen bonds. Molecules 3–6 show the presence of a mixture of enol and cis- and trans-keto forms in the solid state at room temperature. Only two former forms are observed for 2. Compounds 2–6 are exclusively thermochromic, while no photochromism was observed regardless of the irradiation wavelength and time.