Synthesis,coordination properties and DFT studies of novel trans-disubstituted hexaaza-macrocycles containing pyridine and/or ethyldioxolane arms

Abstract

Novel trans-disubstituted hexaaza-macrocyclic ligands L¹ and L² were successfully prepared by the alkylation of the trans secondary amines presented in L with pyridine and ethyldioxolane groups, respectively. The coordination properties of compounds L¹ and L² towards different transition, post-transition and lanthanoid metal ions were explored. Colorless crystals of [NaL¹]I and L^2´Br₂, suitable for X-ray diffraction, were obtained by slow evaporation of an acetonitrile solution of compounds L¹ or L², showing an anti conformation between the methyl groups and the pendant arms in trans positions. The [ML¹]ⁿ⁺ (M?=?Ni²⁺, Cu²⁺, Zn²⁺) systems were investigated by DFT calculations (B3LYP model).     

Synthesis of the [<Superscript>2</Superscript>H,<Superscript>15</Superscript>N]-labeled antiviral drug “triazavirine”

Selective methods for the incorporation of stable isotopes ¹⁵N and ²H into the structure of antiviral medicine “triazavirine” 1 were developed. The synthesized isotopically modified “triazavirine” 1– ² H ₃ , ¹⁵ N ₃ contained the labeled atoms in both the azole and the azine rings. ¹³C and ¹⁵N NMR spectra of the isotope-containing sample 1– ² H ₃ , ¹⁵ N ₃ were thoroughly analyzed.     

Synthetic Ionophores. Part 20: Synthesis and Ionophore Character of 2-Aminothiophenol and 1,3-/1,4-Phenylene Based Silver Selective Receptors

Nucleophilic displacements of 1,3- and 1,4-bis(bromomethyl)benzenes with 2-aminothiophenol provide 1,3- and 1,4- bis(2-aminophenylthiomethyl)benzenes 3 and 11 which undergo intermolecular cyclodehydrochlorination with thiodiglycolyl dichloride and isophthaloyl dichloride to give respectively 6, 8 and 12,13. The diamine 3 and its N,N'-dibenzyl derivative 4 with pyridine-2,6-dicarbonyl dichloride give 7 and 5, respectively. The extraction and transport behaviour of these receptors have been determined towards alkali (Li⁺, Na⁺, K⁺),alkaline earth (Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺), Tl⁺, Ag⁺ and Pb²⁺ picrates.The participation of various ligating sites in binding have been evaluated through ¹³ NMR studies. The acyclic receptors 3, 4 and 11 show higher Ag⁺ selectivity than the cyclic analogs 6 and 12. In the case of acyclic receptor 3 the organisation induced by the 1,3-phenylene spacer and 2-aminophenylthio units and its flexibility generates optimal binding and selectivity towards Ag⁺. However, in cyclicreceptors 3 and 12 though the three thioether unitsare better organised, the inward placement of the NH_amide units restricts the entry of Ag⁺ into the cavity and lowers both the order of binding and selectivity. The lack of binding ability in 7due to an intramolecular NH_amide–-N_py H-bond isrestored in the N-benzyl derivative 5.     

Ester and Ketone Groups Substituted Mono- and Di- Azo-coupled Azocalix[4]arenes as Extractant for Hg+ and Hg2+, or Cr3+Cations

This article describes extraction properties of mono- (A1–A8) and di- (B1–B8) substituted azocalix[4]arene analogues. The ionophore solvent extractions of alkaline-earth (Sr²⁺), basic metal (Pb²⁺) and transition metal cations (Ag⁺, Hg⁺, Hg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cr³⁺) from aqueous phase to organic phase were carried out by azocalix[4]arene derivatives. It has been observed that they show a good extraction behavior toward selected heavy metal (Hg) and toxic metal (Cr), while A4 and B4 prefer Hg⁺, Hg²⁺ and Cr³⁺ among transition metal cations, respectively. The azocalix[4]arenes (A1–A8) and (B1–B8) are not efficient extractants for all of the selected metal cations, whereas A4 and B4 are selective only for Hg metal cation.     

Synthesis,spectral characterization,and evaluation of antimicrobial activity of O,O′-alkanediyl S-(N-phthalimidomethyl) dithiophosphates and zinc bis(O,O′-alkanediyl) dithiophosphates

The synthesis of novel dithiophosphate derivatives has been achieved. Two O,O′-alkanediyl S-(N-phthalimidomethyl) dithiophosphates and two Zinc bis(O,O′-alkanediyl) dithiophosphates are synthesized by an easy and facile chemical synthetic route. Zinc bis[O,O′-(2-methylpentane-2,4-diyl) dithiophosphate] L¹, Zinc bis[O,O′-(2-ethylhexane-1,3-diyl) dithiophosphate] L², O,O′-(2-methylpentane-2,4-diyl) S-(N-phthalimidomethyl) dithiophosphate L³ and O,O′-(2-ethylhexane-1,3-diyl) S-(N-phthalimidomethyl) dithiophosphate L⁴ are synthesized from the respective ammonium salts. Compounds L¹, L², L³, and L⁴ are characterized by (CHN) elemental analysis, ESI mass, FT-IR, ¹H, ¹³C, and ³¹P NMR techniques. The crystal structure of ammonium O,O′-(2-methylpentane-2,4-diyl) dithiophosphate is discussed. L¹, L², L³, and L⁴ were evaluated for antimicrobial activity. It was found that the phthalimide derivatives L³ and L⁴ showed much better antifungal potential against some species of fungus. The Zinc dithiophosphates L¹ and L² showed good antibacterial activity against Bacillus cereus and Escherichia coli.     

Supramolecular dyad derived from a buckybowl series of O2N2-donor naphthodiaza-crowns coordinated to C60: photophysical,NMR and theoretical studies

Supramolecular complexation of C₆₀ with L¹-L⁵ were studied in toluene, chloroform and 1,2-dichlorobenzene solvents using UV–vis, fluorescence, ¹H, ¹³C NMR spectroscopy as well as density functional theory (DFT) calculations. The Job’s plot of continuous variation method established 1:1 stoichiometry for L¹-L⁵/C₆₀. Binding constants (K) calculated for L¹-L⁵/C₆₀ were also determined employing UV–vis and fluorescence spectroscopy. Both steady-state and time-resolved fluorescence spectroscopic surveys showed remarkable fluorescence quenching phenomenon for L¹-L⁵ in the presence of C₆₀ which was primarily attributed to involvement of a static process. The observed fluorescence quenching in L¹–L⁵ was described in terms of both π–π and n–π interactions of the naphthalene moieties and the nitrogen donor groups on the aza-crown macrocyclic ligands with C₆₀, respectively. Moreover, DFT calculations using B₃LYP/6-31G* basis set confirmed on the aforesaid π–π interaction of naphthalene groups on the aza-crowns with C₆₀. The DFT calculations also established significant distributions of charge between C₆₀ and L¹-L⁵ in according to the electronic structure and geometry of L¹-L⁵/C₆₀, very similar to phthalocycnine/C₆₀ systems.     

A criterion for the confluence of two seams of conical intersection in triatomic molecules

It is shown that the cross product t ^{I J} (R _x )≡g ^{I J} (R _x )×h ^{I J} (R _x ), where g _τ ^{I J} (R)=(c ^I (R _x )−c ^J (c ^I (R _x )+c ^J (R _x )), h _τ ^{I J} (R)=c ^I (R _x )^† c ^J (R _x ), τ is an internal nuclear coordinate, the c ^I (R) satisfy [H(R)−E _I (R)]c ^I (R)=0 and H(R) is the electronic Hamiltonian matrix, is a unique property of a conical intersection at R _x . t ^{I J} (R _x )=0 when R _x is located at the intersection of two (or more) seams of conical intersection. This criterion for an intersection of two seams of conical intersection has important implications for algorithms that seek to locate such points. Here it␣is␣used to analyze the trifurcation of a generic C_2v ^2S+1 A−^2S+1 B seam of conical intersection, analogous to those recently found in AlH₂ and CH₂. Received: 31 July 1997 / Accepted: 27 August 1997     

13C, 15N and 113Cd NMR and Molecular Orbital Studies of Novel Bile Acid N-(2-aminoethyl)amides and Their Cd2+-complexes

Lithocholic acid N-(2-aminoethyl)amide (1) and deoxycholic acid N-(2-aminoethyl)amide(2) have been prepared and characterized by¹H, ¹³C and ¹⁵N NMR. The accurate molecular masses of 1 and 2 have been determined by ESI MS. The formation of the Cd²⁺-complexes (1+Cd and 2+Cd) in CD₃OD solution have been detected by ¹H,¹³C, ¹⁵N and ¹¹³Cd NMR. The ¹³C NMR chemical shift assignments of 1 and 2 and their Cd²⁺-complexes are based on DEPT-135 and z-GS ¹H,¹³C HMQC experiments as well as comparison with the assignments of the related structures. The ¹⁵N NMR chemical shiftassignments of the ligands and theirCd²⁺-complexes are based on z-GS¹H,¹⁵N HMBC experiments. ¹³C NMR chemical shift differences between 1and its 1:1 Cd²⁺-complex based on ab initiocalculations at Hartree-Fock SCI-PCM level using3-21G(d) basis set are in agreement with theexperimental shift changes observed onCd²⁺-complexation.     

Generation and characterization of ionic and neutral [HS-P-OH]<Superscript>+/·</Superscript> and S=P(OH)<Stack><Subscript>2</Subscript><Superscript>+/·</Superscript></Stack> in the Gas Phase by Tandem Mass Spectrometry and Computational Chemistry

Dissociative electron ionization of diethyl dithiophosphate (I) and O,O′-diethyl methylphosphonothioate (II) generates moderately abundant m/z 81 ions of composition [P, O, S, H₂]⁺. From tandem mass spectrometry experiments and theoretical calculations at the B3LYP/6-31G(d,p), G2, and G2 (MP2) levels it is concluded that the majority of the ions have the structure of HS-P-OH⁺ (1a ⁺) and it is separated by high-energy barriers from its isomers P(= S)OH₂⁺ (1b ⁺), P(= O)SH₂⁺ (1c ⁺), HP(= S)OH⁺ (1d ⁺), and HP(= O)SH⁺ (1e ⁺). Low-energy (metastable) ions 1a ⁺ dissociate via losses of H₂O and H₂S to yield m/z 63 (PS⁺) and m/z 47 (PO⁺) product ions, respectively. These reactions involve isomerization of 1a ⁺ into the stable isomers 1b ⁺ and 1c ⁺. Neutralization-reionization experiments confirm the theoretical prediction that radical 1a ^· is a stable species in the gas-phase. Variable-time NR experiments indicated that only a small fraction of metastable 1a ^· radicals dissociate in the 0.4–4.6 μs time window, while most dissociations occurred on a shorter time scale. RRKM calculations were performed to investigate unimolecular dissociation kinetics of 1a ^· which were found to be in agreement with the fragmentation observed in the NR spectrum. The 70-eV electron ionization of (I) and diethyl chlorothiophosphate (III) yields m/z 97 ions, predominantly of the structure S = P(OH)₂⁺ (2a ⁺). This conclusion follows from tandem mass spectrometry experiments and theoretical calculations. The calculations predict that (2a ⁺) is separated by high-energy barriers from its isomers O = P(SH)OH⁺ (2b ⁺), S = P(= O)OH₂⁺ (2c ⁺), and O = P(= O)SH₂⁺ (2d ⁺). Neutralization-reionization experiments confirmed that 2a ^· radical is a kinetically stable species on the time scale of up to 5 μs, which is in agreement with ab initio calculations. However, owing to a mismatch of Franck-Condon factors a large fraction of 2a ^· dissociates by loss of SH^· yielding O=P-OH.     

Double-armed and tetra-armed cyclen-based cryptands

Double-armed and tetra-armed cyclen-based cryptands (1a–1d and 2) that bridge two aromatic rings by diethyleneoxy and triethyleneoxy units were prepared. The CSI-MS of 1:1 mixtures ([Ag⁺]/[ligand]) indicated that these new cryptands form 1:1 complexes with Ag⁺. The log K values for the interaction between Ag⁺ and 2 was greater than those of 1a–1d, double-armed cyclens (3a–3c and 4), and tetra-armed cyclen (5). The Ag⁺-ion-induced ¹H NMR spectral changes suggest that the Ag⁺–π interactions of the Ag⁺ complexes with the cryptands (1a–1d and 2) are stronger than those in Ag⁺/double-armed and tetra-armed cyclens. To visualise the Ag⁺?π interactions, the isosurfaces of the LUMO and HOMOs of the Ag⁺ complexes were calculated at the B3LYP/3–21G(*) theoretical level. The LUMO of the Ag⁺ ion is distorted by interaction with the HOMOs of the aromatic side arms. The calculations reveal Ag⁺?π interactions between the Ag⁺ ion and the aromatic side arms, and these are shown graphically.     

Two 1-D and 2-D cobalt(II) complexes: synthesis,crystal structures,spectroscopic and electrochemical properties

Two new cobalt(II) complexes, [Co(L³)₂]·CH₃OH·CH₃COCH₃ (1) (HL³ = 1-(2-{[(E)-3,5-dichloro-2-hydroxybenzylidene]amino}phenyl)ethanone oxime) and Co(L⁴)₂ (2) (HL⁴ = 1-(2-{[(E)-3,5-dibromo-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), have been synthesized via complexation of Co(II) acetate tetrahydrate with HL¹ and HL². HL¹, HL², and their corresponding Co(II) complexes were characterized by IR, ¹H NMR spectra, as well as by elemental analysis and UV–Vis spectroscopy, respectively. The crystal structures of the complexes have been determined by single-crystal X-ray diffraction. 1 and 2 display that extensive hydrogen bonds and C–X···π bonding interactions construct the 1-D infinite chain [Co(L³)₂]·CH₃OH·CH₃COCH₃ and Co(L⁴)₂ into 2-D supramolecular frameworks. The electrochemical properties of two Co(II) complexes were also investigated by cyclic voltammetry.     

Synthesis of a Calix[4]crown‐6 Cone Conformer‐Based Oligomer and its Metal Cation Extraction Abilities

A new calixcrown‐6 oligomer 5 was synthesized by reacting a 1,3‐distal di‐amino derivative of cone p‐tert‐butylcalix[4]crown‐6 with malonyl dichloride. Extraction studies with precursor monomers 2 and 3 and oligomer 5 showed differences in their metal cation extraction behavior and selectivity. Precursors monomers 2 and 3 were selective for Hg²⁺; whereas, oligomer 5 showed high affinity towards both alkali (Li⁺, Na⁺, K⁺, and Cs⁺) and heavy metal cations (Cu²⁺, Cd²⁺, Hg²⁺ and Pb²⁺).     

Zinc(II) and mercury(II) complexes with Schiff bases: syntheses,spectral, and structural characterization

Schiff bases o-vanilidene-1-aminobenzene (HL¹) and o-vanilidene-2-methyl-1-aminobenzene (HL²) lead to the formation of mono- and bis-[(Cl)Zn(L¹)] (1), [(Cl)Zn(L²)] (2), [(Cl)Hg(L¹)] (3), [(Cl)Hg(L²)] (4), [Zn(L¹)₂] (5), [Zn(L²)₂] (6), [Hg(L¹)₂] (7), and [Hg(L²)₂] (8) complexes by reactions of zinc(II) and mercury(II) chlorides in different mole ratio(s). Complexes 1–8 have been characterized by elemental analyses (Zn, Hg, C, H, Cl, and N), melting point and spectral (IR, ¹H-NMR), PXRD, molar conductivity measurement, and TGA. Conductivity measurements suggest non-electrolytes. Structural compositions have been assigned by mass spectral studies. Four-coordinate geometry may be assigned to these complexes tentatively. Structural study reveals that in 1–4 two metal centers are held together by two bridged (μ₂-Cl) chlorides, whereas 5–8 contain two bidentate Schiff-base ligands around one metal-producing monomers.     

Bis(naphthol)-based fluorescent chemoprobe for cesium cation and its immobilisation on silica nanoparticle as a high selective adsorbent

Abstract

A bis(naphthol)-based cation receptor 1 has been synthesised by three steps of synthetic procedure. The spectroscopic properties of 1 upon addition of various metal ions were investigated by UV–vis absorption and fluorescence spectroscopy. As a result, the absorption of 1 was linearly decreased as a function of concentration of added Cs⁺. Also, 1 exhibited dramatic fluorescence quenching effect upon exposure to caesium cation. Contrastively, no significant quenching effect was observed upon addition of other metal ions such as Na⁺, K⁺, Rb⁺, Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Ni²⁺ and Zn²⁺. It was found that 1 formed a 1:1 complex with Cs⁺ by Job’s plot. Furthermore, we also prepared 1-functionalised silica nanoparticle (SiO₂-1) as an adsorbent for Cs⁺. SiO₂-1 showed a great capacity for selective removal of caesium ion from aqueous solution as well as from tap water. Thus, it is potentially useful for the detection and removal of caesium cation from environmental and biological fluids polluted by nuclear radiation and nuclear waste.     

Synthesis and Characterization of New Metal-free and Metallophthalocyanines Substituted with Tetrathiadiazamacrobicyclic Moieties

New metal-free (5, 8) and metallophthalocyanines (6, 9) containing four diazatetrathiamacrobicycles or crosswise-disubstituted attached with two nitro and two macrobicyclic groups were synthesized by cyclotetramerization of 7,8-dicyano-4,11,22,23-tetrathia-1,14-diazapentacyclo[12.10.10.0^5,10.0^16,21.0^26,31]tetratriconta-5,7,12,19,20,21,28,30,32-nonane (3), 8,10-dihydro-8,11-diimino-4,14,24,34,-tetrathia-1,17-diazapentacyclo[15.13.13.0^5,13.0^19,23.0^28,33]tetratriconta-5,7,12,19,20,22,28,30,32-nonaisoiminoindoline (4) or 6-nitro-1,3,3-trichloroisoindolenine (7) in the presence of the corresponding metal salt or a strong organic base. The new compounds were characterized by a combination of elemental analysis and ¹H NMR, ¹³C NMR, IR, UV–Vis and MS spectral data.     

Imides of 2-Trifluoroacetylphenol and other Trifluoracetic acid Esters: Novel Reactions with Phosphorus(III) Derivates

Abstract

The imido derivates of 2-trifluoroacetylphenol, 1 (R¹=H, Me, iPr) react with the isocyanatophosphites (R²O)₂PNCO, 2 (R²[dbnd]Et, R²-R²[dbnd]CMe₂-CMe₂) to yield the bicyclic compounds 3, wheras in case of 1 (R¹[dbnd](CH₂)₂NMe2) the λ³σ³P compounds 4 are found. The phosphorus(III) chlorides R3PC12 (R³[dbnd]Ph, OEt) and 1 (R¹[dbnd]H, Me) give rise to furnish the tricyclic phosphoranes 5. However with 1 (R¹[dbnd]iPr) phosphite 6 is obtained, which adds hexafluoracetone to give the 1,3,2λ⁵σ⁵-dioxaphospholane 7. 2-(Trifluoracetoxy)pyridine 8. reacts with Tris(trimethylsily1)phosphite to yield the bis(phosph0nate) 10. Some molecular structures are discussed on the basis of x-ray diffraction results.     

Excellent Ag+ selective receptors: Syntheses and complexation properties of novel biscalix[4]arene with benzalazine groups

By reacting mono-substituted or 1,3-bi-substituted [2-(p-formylphenyloxy)ethyloxy]-p-tert-butylcalix[4]arene (3 or 4) with hydrazine hydrate in ‘1+2’ or ‘2+2’ condensation mode, novel benzalazine-bridging biscalix[4]arenes 5 and 7 were conveniently obtained in the yields of 76 and 81%, respectively. Condensation of compound 4 and salicylide hydrazone gave a novel calix[4]arene benzalazine derivative 6 in the yield of 85%. The structures and conformations of all new compounds were characterised by elemental analyses, ESI-MS, ¹H NMR and ¹H–¹H COSY techniques. Biscalix[4]arene 7 adopts a symmetrical cone conformation with tube cavity. The liquid–liquid extraction experiment showed that all new hosts possessed excellent complexation abilities towards soft metal cations. Compound 7 exhibited high complexation selectivity towards Ag⁺. The Ag⁺/Na⁺ and Ag⁺/Hg²⁺ extraction percentages of host 7 were as high as 73.1 and 54.9, respectively. The UV–vis spectra complexation experiments revealed that the complexation constant of receptor 7 with Ag⁺ was 1.9 × 10⁵ M^? 1 and the 1:1 stoichiometry of receptor 7–Ag⁺ complex was formed. The ¹H NMR spectra complexation experiments suggested that Ag⁺ was bound in a cavity composed of two benzalazine groups on bridging chains.     

Different conjugated system Cd(II)/Hg(II) Schiff base complexes: syntheses,supramolecular metal−organic frameworks,luminescent properties and DFT study

A series of different conjugated systems of 2D/3D supramolecular metal-organic frameworks (SMOFs) are constructed by C/O?H?Cl hydrogen bonds and π?π interactions. These complexes, [HgL¹Cl₂] (1), [HgL²Cl₂] (2), [HgL³Cl₂] (3), [CdL⁴Cl₄]₂ (4), and [CdL⁵Cl₂(CH₃OH)] (5), have been synthesized and characterized by single-crystal X–ray diffraction, ¹H NMR, FT–IR, and EA. The X-ray diffraction analyses reveal that 1 features a 3D supramolecular framework with {4⁴·6⁶} topology structure, while 2, 3, and 5 exhibit 3D 6-connected {4¹²·6³} topology structures. Complex 4 shows a two-dimensional layer with 4⁴ topology structure. Based on these varied structures caused by different conjugated system, the emission maximum wavelengths of 1–5 can be tuned in a large range of 492–587 nm. Both electron-donating ability and the conjugated system in general can support λ_em shift to red direction. In order to have better understanding of electronic transitions of the complexes, a time-dependent DFT study has been performed. The enhancement of the fluorescence intensities for the complexes compared to the ligands indicates potential to serve as photoactive materials.     

Four chromophores in one building block: synthesis,structure and characterization of trans-[Ru(MQ)4Cl2]4+ and trans-[Ru(4,4’-bpy)4Cl2] (MQ+ = N-methyl-4,4’-bipyridinium,bpy = bipyridine)

We report the synthesis, crystal structure, electrochemical and spectroscopic properties of trans-[Ru(MQ)₄Cl₂]⁴⁺ (1⁴⁺), where MQ⁺ = N-methyl-4,4′-bipyridinium. The crystal structure of 1⁴⁺ shows the pyridinic rings bound in a trans fashion to the Ru ion. In 1⁴⁺ and in its analog trans-[Ru(4,4′-bpy)₄Cl₂] (2, bpy = bipyridine), the electrochemical reduction waves of the four iminic ligands occur at very closely spaced potentials. In comparison with previously reported analogues, 1⁴⁺ and 2 present high molar extinction coefficients (ε = 20,000–50,000 M^–1cm^–1), and red-shifted absorptions (up to 800 nm for 1⁴⁺ and up to 600 nm for 2) in acetonitrile. Upon protonation of the four exposed nitrogens of 2 and electrochemical reduction of the ligands in 1⁴⁺ and 2, spectral changes occur with retention of isosbestic points, revealing the presence of four independent chromophores. These results suggest poor electronic communication between the aromatic ligands within each compound, in contrast to related complexes such as cis-[Ru(2,2′-bpy)₂Cl₂] (3).