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Introduction of a methoxymethyloxy (MOMO) group at one of the four quinoline rings of TQEN (N,N,N′,N′-tetrakis-(2-quinolylmethyl)ethylenediamine) affords Cd2+-selective fluorescence enhancement.

Introduction of three methoxy groups at 5-, 6- and 7-positions of quinoline rings of BQDMEN (N,N′-bis(2-quinolylmethyl)-N,N′-dimethylethylenediamine) affords Cd2+-selective fluorescence enhancement.

A bis(μ-oxo)diiron(IV,IV) complex as a model for intermediate Q in the methane monooxygenase reaction cycle has been prepared. The precursor complex with a [FeIIIFeIV(μ-O)2] core was fully characterized by X-ray crystallography and other spectroscopic analyses and was converted to the [FeIV2(μ-O)2] complex via electrochemical oxidation at 1000 mV (vs Ag/Ag+) in acetone at 193 K. The UV-vis spectral features, Mossbauer parameters (ΔEQ = 2.079 mm/s and δ = -0.027 mm/s), and EXAFS analysis (Fe-O/N = 1.73/1.96 A and Fe···Fe = 2.76 A) support the structure of the low-spin (S = 1, for each Fe) [FeIV2(μ-O)2] core. The rate constants of the hydrogen abstraction reaction from 9,10-dihydroanthracene at 243 K suggest the high reactivity of these synthetic bis(μ-oxo)diiron complexes supported by simple N4 tripodal ligand.

Moderate Zn

Intramolecular cycloaddition reactions of α-bromostyrene-functionalized amides of monomethyl fumarate were investigated. The reaction of the amides with Et

Seven new bis(μ-oxo)dimanganese complexes with Mn2(III,III) or Mn2(III,IV) oxidation states were prepared using quinoline- and isoquinoline-based tetraamine ligands. The structures of the ligands include ethylenediamine, trans-1,2-cyclohexanediamine and tripodal amine, bearing two or three nitrogen-containing heteroaromatics. Regardless of the skeleton and number of aliphatic nitrogen atoms in the ligands, quinoline complexes stabilize the Mn2(III,III) oxidation state, whereas, isoquinoline ligands afford Mn2(III,IV) complexes. A systematic comparison of the differences in structural parameters and redox potentials of a total of 14 complexes with a (μ-O)2Mn2 diamond core, which includes corresponding pyridine and quinoxaline derivatives as supporting ligands, highlights the distinct deviation of quinoline and tripodal amine motifs in this ligand series.

Inter- and intramolecular cycloaddition reactions of ethenetricarboxylates with styrenes and α-halostyrenes have been investigated. The reactions of ethenetricarboxylates with styrenes or α-bromostyrenes in the presence of SnCl4 or SnBr4 stereoselectively gave 2,4-cis-substituted cyclobutanes. The intramolecular cycloaddition reactions of a series of styrene-functionalized ethenetricarboxylate amides, including in situ generated derivatives, showed high diversity of reaction modes depending on the structures and substituents of the substrates. The regioselectivity and stereoselectivity of the reactions as well as reaction mechanisms were discussed based on the DFT calculations.

A quinoline-based hexadentate ligand, (S,S)-N,N,N′,N′-tetrakis(6-methoxy-2-quinolylmethyl)-1,2-diphenylethylenediamine ((S,S)-6-MeOTQPh2EN), exhibits fluorescence enhancement at 498 nm upon additio...

Rational molecular structure alterations of TQEN (N,N,N',N'-tetrakis(2-quinolylmethyl)ethylenediamine) produced variable fluorescent sensors for specific metal ions and phosphate species. Utilization of methoxy-substituted quinoline and isoquinoline chromophores, conformational restriction and multidentate coordination structure allow discrimination between Zn2+ and Cd2+. Pyrophosphate (P2O74-, PPi) and phosphate (PO43-) also are selectively detected with dinuclear Zn2+ complexes of tetrakisquinoline-based ligands. Differential stability and structure of the metal complexes, as well as resulting fluorescence enhancement mechanism, such as intramolecular excimer formation via change in coordination geometry, play key roles in the discrimination of target ions.

A bis(μ-oxo)diiron(IV,IV) complex as a model for intermediate Q in the methane monooxygenase reaction cycle has been prepared. The precursor complex with a [Fe

Mechanistic understanding of the asymmetric autocatalysis of pyrimidyl alkanol is a highly attractive and challenging topic due to its unique feature of amplification of enantiomeric excess. Circular dichroism spectroscopic analysis of this reaction allows monitoring of the structual changes of possible catalyst precursors in the solution state and shows characteristic temperature and solvent dependence. TD-DFT calculations suggest that these spectral changes are induced by a dimer–tetramer equilibrium of zinc alkoxides.

EGTA (ethylene glycol bis(2-aminoethyl ether)-N,N,N′,N′-tetraacetic acid) and BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid) are well-known Ca2+ chelators that have four carboxylates, two nitrogen atoms and two ether oxygen atoms. In the present study, we prepared EGTQ (N,N,N′,N′-tetrakis(2-quinolylmethyl)-1,2-bis(2-aminoethoxy)ethane) and BAPTQ (N,N,N′,N′-tetrakis(2-quinolylmethyl)-1,2-bis(2-aminophenoxy)ethane) as quinoline alternatives of EGTA and BAPTA, respectively. In methanol–HEPES buffer solution (9 : 1, 50 mM HEPES, 0.1 M KCl, pH = 7.5), EGTQ exhibits fluorescence enhancement induced by Zn2+ and Cd2+ with poor selectivity, but BAPTQ did not exhibit a fluorescence response to either metal ion. Introduction of three methoxy substituents at the 5,6,7-positions of each quinoline moiety in BAPTQ specifically enhanced the fluorescence intensity of the Cd2+ complex, establishing the Cd2+-specific probe TriMeOBAPTQ (N,N,N′,N′-tetrakis(5,6,7-trimethoxy-2-quinolylmethyl)-1,2-bis(2-aminophenoxy)ethane). In contrast, TriMeOEGTQ (N,N,N′,N′-tetrakis(5,6,7-trimethoxy-2-quinolylmethyl)-1,2-bis(2-aminoethoxy)ethane) maintains a poor Cd2+/Zn2+ selectivity in its fluorescence response. Although the crystal structures of Cd2+/Zn2+ complexes with EGTQ and BAPTQ derivatives reveal the formation of multiple components including mononuclear and dinuclear complexes, the dinuclear Cd2+ and Zn2+ complexes with a linearly extended structure are regarded as possible fluorescent species in the solution. The conformational restriction of BAPTQ due to the orthophenylene moieties in the molecular skeleton is responsible for the formation of the weakly fluorescent, OH-bridged dizinc complex, which is critical to the strict Cd2+-specificity in the fluorescence response of TriMeOBAPTQ.

A quinoline-based hexadentate ligand, (

The crystal structure of salt 4 prepared from (S)-3,3,3-trifluoro-2-methoxy-2-phenylpropanoic acid [(S)-MTPA, (S)-1] and (R)-1-phenylethylamine [(R)-PEA, (R)-2] was determined using X-ray crystallo...

A quinoline-based heptadentate ligand, N,N,N′,N′-tetrakis(2-quinolylmethyl)-3-oxa-1,5-pentanediamine (TQOPEN), exhibits a fluorescence increase (ICd/I0 = 25, ϕCd = 0.017) at 428 nm upon addition of 1 equiv of Cd2+. In contrast, 1 equiv of Zn2+ induces a negligible fluorescence change due to weak interaction (IZn/I0 = 2.5, IZn/ICd = 10%). In comparison with TQOPEN, the thia and aza derivatives TQSPEN and TQNPEN exhibit improved Cd2+/Zn2+ selectivity and higher Cd2+-binding affinity, respectively. The solid-state structures of mononuclear Cd2+ and hydroxide-bridged dinuclear Zn2+ complexes of TQOPEN were elucidated by X-ray crystallography. Although the crystal structure of the TQOPEN-Cd2+ complex exhibits a six-coordinate metal center, in which one quinoline weakly interacts with the Cd center (Cd···Nquinoline = 3.303(3) A), a 1H NMR study at 233 K suggests that all quinolines interact with the Cd center to form a symmetrical seven-coordinate structure in solution. Theoretical calculations (TDDFT) support ...

A quinoline-based heptadentate ligand, N,N,N',N'-tetrakis(2-quinolylmethyl)-2,6-bis(aminomethyl)pyridine (TQLN), exhibits a Zn2+-specific fluorescence increase at 428 nm, which is assigned to excimer emission (IZn/I0 = 38, ICd/IZn = 24%, ϕZn = 0.069). In contrast, the isoquinoline counterpart 1-isoTQLN exhibits a Cd2+-specific fluorescence increase at 365 nm attributable to monomer emission (ICd/I0 = 83, IZn/ICd = 19%, ϕCd = 0.015).

By using the Warburg effect&mdash, a phenomenon where tumors consume higher glucose levels than normal cells&mdash, on cancer cells to enhance the effect of photodynamic therapy (PDT), we developed a new photosensitizer, glucose-conjugated chlorin e6 (G-Ce6). We analyzed the efficacy of PDT with G-Ce6 against canine mammary carcinoma (CMC) in vitro and in vivo. The pharmacokinetics of G-Ce6 at 2, 5, and 20 mg/kg was examined in normal dogs, whereas its intracellular localization, concentration, and photodynamic effects were investigated in vitro using CMC cells (SNP cells). G-Ce6 (10 mg/kg) was administered in vivo at 5 min or 3 h before laser irradiation to SNP tumor-bearing murine models. The in vitro study revealed that G-Ce6 was mainly localized to the lysosomes. Cell viability decreased in a G-Ce6 concentration- and light intensity-dependent manner in the PDT group. Cell death induced by PDT with G-Ce6 was not inhibited by an apoptosis inhibitor. In the in vivo study, 5-min-interval PDT exhibited greater effects than 3-h-interval PDT. The mean maximum blood concentration and half-life of G-Ce6 (2 mg/kg) were 15.19 &plusmn, 4.44 &mu, g/mL and 3.02 &plusmn, 0.58 h, respectively. Thus, 5-min-interval PDT with G-Ce6 was considered effective against CMC.

EGTA (ethylene glycol bis(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid) and BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid) are well-known Ca2+ chelators that have four carboxylates, two nitrogen atoms and two ether oxygen atoms. In the present study, we prepared EGTQ (N,N,N',N'-tetrakis(2-quinolylmethyl)-1,2-bis(2-aminoethoxy)ethane) and BAPTQ (N,N,N',N'-tetrakis(2-quinolylmethyl)-1,2-bis(2-aminophenoxy)ethane) as quinoline alternatives of EGTA and BAPTA, respectively. In methanol-HEPES buffer solution (9 : 1, 50 mM HEPES, 0.1 M KCl, pH = 7.5), EGTQ exhibits fluorescence enhancement induced by Zn2+ and Cd2+ with poor selectivity, but BAPTQ did not exhibit a fluorescence response to either metal ion. Introduction of three methoxy substituents at the 5,6,7-positions of each quinoline moiety in BAPTQ specifically enhanced the fluorescence intensity of the Cd2+ complex, establishing the Cd2+-specific probe TriMeOBAPTQ (N,N,N',N'-tetrakis(5,6,7-trimethoxy-2-quinolylmethyl)-1,2-bis(2-aminophenoxy)ethane). In contrast, TriMeOEGTQ (N,N,N',N'-tetrakis(5,6,7-trimethoxy-2-quinolylmethyl)-1,2-bis(2-aminoethoxy)ethane) maintains a poor Cd2+/Zn2+ selectivity in its fluorescence response. Although the crystal structures of Cd2+/Zn2+ complexes with EGTQ and BAPTQ derivatives reveal the formation of multiple components including mononuclear and dinuclear complexes, the dinuclear Cd2+ and Zn2+ complexes with a linearly extended structure are regarded as possible fluorescent species in the solution. The conformational restriction of BAPTQ due to the orthophenylene moieties in the molecular skeleton is responsible for the formation of the weakly fluorescent, OH-bridged dizinc complex, which is critical to the strict Cd2+-specificity in the fluorescence response of TriMeOBAPTQ.

The tetrakisquinoline ligand HT(6-MeO8Q)HPN (N,N,N′,N′-tetrakis(6-methoxy-8-quinolylmethyl)-2-hydroxy-1,3-propanediamine) exhibited Zn2+-induced fluorescence enhancement with high specificity and sensitivity (IZn/I0 = 57 and ICd/IZn = 6% in the presence of 2 equiv of Zn2+; LOD (limit of detection) = 15 nM). This ligand also exhibited fluorescence enhancement specific to inorganic phosphate (PO43–) in DMF–HEPES buffer (50 mM HEPES, 100 mM KCl, pH = 7.5) (1:1) in the presence of 2 equiv of Zn2+. The structure of the unprecedented tetranuclear zinc complex with a μ4-PO4 bridge was elucidated by X-ray crystallography as the key species responsible for fluorescence enhancement.

Intramolecular [2 + 2] and [4 + 2] cycloaddition reactions of cinnamylamides of ethenetricarboxylate in sequential processes have been studied. Reaction of 1,1-diethyl 2-hydrogen ethenetricarboxylate and trans-cinnamylamines in the presence of EDCI/HOBt/Et3N led to pyrrolidine products in one pot, via intramolecular [2 + 2], [4 + 2], and some other cyclizations. The types of the products depend on the substituents on the benzene ring and the reaction conditions. Reaction of cinnamylamines without substituents on the benzene ring and with halogens and OMe on the para position at room temperature gave cyclobutane-fused pyrrolidines as major products via [2 + 2] cycloaddition. The reaction at 80 °C in 1,2-dichloroethane gave δ-lactone fused pyrrolidines as major products, probably via ring-opening of the cyclobutanes. Interestingly, reaction of 1,1-diethyl 2-hydrogen ethenetricarboxylate and cinnamylamines bearing electron-withdrawing groups such as NO2, CN, CO2Me, CO2Et, and CF3 on ortho and para positions ...

Quinoxaline-based tetranitrogen ligand, N,N’-bis(2-quinoxalylmethyl)-N,N’-dimethylethylenediamine (L9), stabilizes the bis(µ-hydroxo) dinuclear manganese(II,II) core. Oxidation of the complex with hydrogen peroxide in methanol suspension affords the bis(µ-oxo) dinuclear manganese(III,III) complex. The quinoxaline-based tripod ligand, tris(2-quinoxalylmethyl)amine (L11), did not afford corresponding bis(hydroxo) dimanganese(II,II) complex due to the subsequent atmospheric oxygen-promoted oxidation in the reaction solution similar to its quinoline counterpart, tris(2-quinolylmethyl)amine (L10). The solid state structures of [Mn(II)Cl2(L9)], [(µ-OH)2Mn2(II,II)(L9)2]2+, [(µ-O)2Mn2(III,III)(L9)2]2+, [(µ-O)2Mn2(III,III)(L11)2]2+, and [(µ-O)2Mn2(III,III)(L10)2]2+ complexes were determined by X-ray crystallography. The magnetic susceptibility measurement of (µ-OH)2Mn2(II,II) complex and electrochemical oxidation of (µ-O)2Mn2(III,III) complexes were performed to evaluate the tetramine ligand effect stabilizing the low oxidation states of dinuclear metal center supported by two oxygen atom bridges.

Dinuclear Zn2+ complexes with HTQHPN (N,N,N′,N′-tetrakis(2-quinolylmethyl)-2-hydroxy-1,3-propanediamine) derivatives have been prepared, and their pyrophosphate (PPi, P2O74–) sensing properties wer...

Fifteen bisquinoline derivatives with a thioether linker have been prepared, and their Hg2+- and Fe3+-specific fluorescence responses have been investigated. Upon the addition of Hg2+ ions, unsubstituted 2-quinolylmethyl derivatives 1a–1c exhibit a fluorescence enhancement (off–on) response. On the other hand, ratiometric and fluorescence quenching (on–off) responses are accomplished for derivatives with monomethoxy (2a–2c) and trimethoxy (3a–3c) substituents on the aromatic ring, respectively. The 8-quinolylmethyl derivatives 4a–4c and 5a–5c exhibit a similar response pattern to those of 1 and 2 with enhanced Hg2+ ion selectivity. Increasing the number of sulfur atoms through the extension of the linker chain also improves the Hg2+ ion selectivity.

TQPHEN (N,N,N',N'-tetrakis(2-quinolylmethyl)-1,2-phenylenediamine) and its methoxy-substituted derivatives, 6-MeOTQPHEN (N,N,N',N'-tetrakis(6-methoxy-2-quinolylmethyl)-1,2-phenylenediamine) and TriMeOTQPHEN (N,N,N',N'-tetrakis(5,6,7-trimethoxy-2-quinolylmethyl)-1,2-phenylenediamine), were examined as fluorescent Cd(2+) sensors. Although the TQPHEN exhibits a negligible fluorescence response toward Zn(2+) due to weak binding affinity in DMF-H2O (1:1), a 6-fold fluorescence enhancement at 392 nm was observed in the presence of 1 equiv. of Cd(2+). Comprehensive X-ray crystallographic analyses of TQPHEN-Zn(2+) and TQPHEN-Cd(2+) complexes reveal that significant distortion in the Zn(2+) complex plays a key role in the Cd(2+) specificity of TQPHEN. The TriMeOTQPHEN exhibits excellent sensitivity and selectivity for Cd(2+) detection (ICd/I0 = 44, ICd/IZn = 20 and LODCd = ∼10 nM (LOD = limit of detection)). On the other hand, the trans-1,2-cyclohexanediamine derivative TQDACH (N,N,N',N'-tetrakis(2-quinolylmethyl)-trans-1,2-cyclohexanediamine) exhibits high Zn(2+) specificity in the fluorescence response and extremely high Zn(2+) binding affinity (Dalton Trans., 2013, 42, 9688). Subtle differences in the PHEN and DACH backbone significantly alter the stability with a specific metal and the fluorescence response of tetrakisquinoline-based fluorescent probes.

A convenient synthesis of C3-symmetric tribenzylamine (TBA) derivatives has been investigated. The reaction of benzyl chlorides with acetaldehyde ammonia trimer () in the presence of base afforded tribenzylamines in high yields. This efficient method allows the diverse synthesis of TPA (tris(2-pyridylmethyl)amine) and TQA (tris(2-quinolylmethyl)amine) derivatives. Among the TQA compounds prepared, tris(8-methoxy-2-quinolylmethyl)amine (8-MeOTQA, ) exhibited superior properties as a fluorescent zinc probe with high quantum yield (ϕZn = 0.51) and high sensitivity (limit of detection (LOD) = 3.4 nM). The X-ray crystallographic analysis of [Zn(8-MeOTQA)](2+) revealed that the steric and electronic effect of 8-methoxy substituents kicks out the solvent and counterion molecules from the metal coordination sphere, resulting in short Zn-Nquinoline coordination distances (2.04-2.07 Å). The pseudo hexacoordinate complex of 6-methoxy derivative, [Zn(6-MeOTQA)(DMF)(ClO4)](+), exhibited longer Zn-Nquinoline distances (2.07-2.19 Å) and much smaller fluorescence intensity (ϕZn = 0.027). The replacement of one of the three 8-methoxyquinolines with pyridine also afforded much less fluorescent zinc complex (ϕZn = 0.095) due to the solvent coordination (Zn-Nquinoline = 2.05-2.18 Å for [Zn(8-MeOBQPA)(CH3OH)](2+)).

The crystal structures of salts 6–9 prepared from (R)-2-methoxy-2-(1-naphthyl)propanoic acid [(R)-MαNP acid, (R)-1] and (R)-1-arylethylamines [salt 6, (R)-1-(4-methoxyphenyl)ethylamine∙(R)-1; salt 7, (R)-1-(4-fluorophenyl)ethylamine∙(R)-1; salt 8, (R)-1-(4-chlorophenyl)ethylamine∙(R)-1; and salt 9, (R)-1-(3-chlorophenyl)ethylamine∙(R)-1] were elucidated by X-ray crystallography. The solid-state associations and conformations of the MαNP salts were defined using the concepts of supramolecular- and planar chirality, respectively, and the crystal structures of salts 6–9 were interpreted as a three-step hierarchical assembly. The para-substituents of the (R)-1-arylethylammonium cations were found on sheet structures consisting of 21 columns. Thus, salts possessing smaller para-substituents, that is, salt 7 (p-F) and salt 9 (p-H), and larger para-substituents, that is, salt 6 (p-OMe) and salt 8 (p-Cl), crystallized in the space groups P21 and C2, respectively. Additionally, weak intermolecular interactions, that is, aromatic C–H···π, C–H···F, and C–H···O interactions, were examined in crystalline salts 6–9.

A quinoline-based heptadentate ligand, N,N,N',N'-tetrakis(2-quinolylmethyl)-3-oxa-1,5-pentanediamine (TQOPEN), exhibits a fluorescence increase (I

A quinoline-based heptadentate ligand, N,N,N',N'-tetrakis(2-quinolylmethyl)-2,6-bis(aminomethyl)pyridine (TQLN), exhibits a Zn

A chlorophyll-a derivative possessing a trifluoroacetylacetonate moiety at the C3 position was prepared by Claisen condensation of the 3-acetyl group with ethyl trifluoroacetate in the presence of sodium methoxide. The Claisen condensation was successfully applied for the reaction of 3-acetyl-chlorin with ethyl pentafluoropropionate as well as that of 3-acetyl-bacteriochlorin with ethyl trifluoroacetate. The resulting Claisen condensation products took exclusively diketonate conformers in a CDCl3 solution and the single crystal, and gave red-shifted and broadened Qx/Qy absorption bands in the visible to near-infrared region, compared with the corresponding 3-acetyl-(bacterio)chlorins.

The tetrakisquinoline ligand HT(6-MeO8Q)HPN (N,N,N',N'-tetrakis(6-methoxy-8-quinolylmethyl)-2-hydroxy-1,3-propanediamine) exhibited Zn

An isoquinoline-based ligand, N,N,N',N'-tetrakis(1-isoquinolylmethyl)-2-hydroxy-1,3-propanediamine (1-isoHTQHPN), exhibits a fluorescence increase at 475 nm upon addition of 1 equiv. of Zn(2+) (IZn/I0 = 12, ϕZn = 0.023). This fluorescence enhancement turns and then decreases sharply after the addition of more than 1 equiv. of Zn(2+) reaching a constant minimum intensity with more than 2 equiv. of Zn(2+). In contrast, the fluorescence intensity at 353 nm continues to increase until the signal saturates at ca. 5 equiv. of Zn(2+). This observation can be explained by the formation of a fluorescent mononuclear complex ([Zn(1-isoHTQHPN)](2+)) followed by a non-fluorescent dinuclear complex ([Zn2(1-isoTQHPN)](3+)) at 475 nm during the titration of 1-isoHTQHPN with Zn(2+). Both the mono- and dinuclear complexes were characterized by UV-vis, fluorescence, (1)H NMR, ESI-MS, X-ray crystallography and TDDFT calculations. The fluorescence enhancement at 475 nm is Zn(2+)-specific; Cd(2+) induces a much smaller emission increase (ICd/I0 = 3.7, ICd/IZn = 31%). The Zn(2+)/Cd(2+) selectivity of the fluorescent response correlates with the difference in excimer-forming ability derived from the Cd-Nisoquinoline and Zn-Nisoquinoline bond distances.

A series of porphyrin derivatives with one to four maltohexaose moieties in their meso positions have been synthesized. Zinc or free-base m-THPP (5,10,15,20-tetrakis(m-hydroxyphenyl)-porphyrin) was used as the porphyrin platform. The reaction of m-THPP with 3-iodopropyl nonadecaacetylmaltohexaoside afforded a mixture of all possible combinations of glycoconjugated porphyrins having one to four maltohexaose moieties; monoglycosylated (Ac-1), bisglycosylated (Ac-cis-2 and Ac-trans-2), triglycosylated (Ac-3), and tetraglycosylated (Ac-4) porphyrins were obtained in 11–26% yield. Removal of acetyl groups at maltohexaose moiety afforded highly water-soluble glycoconjugated porphyrins 1–4. Zinc derivatives were synthesized in a similar manner. These maltohexaose-linked porphyrins exhibit remarkable water-solublity (530 mg/mL for 4). The singlet oxygen production ability upon visible light irradiation is not affected by the maltohexaose substitution. Photo- and dark cytotoxicities of the maltohexaose-conjugated porphyrins 1–4 and Zn-1–4 were examined against a HeLa cell line, which showed that the mono-maltohexaosylated derivative (1 and Zn-1) was the most effective photosensitizer for PDT.

Four platinum(II) and palladium(II) complexes with sugar-conjugated bipyridine-type triazole ligands, [Pt(II)Cl(2)(AcGlc-pyta)] (3), [Pd(II)Cl(2)(AcGlc-pyta)] (4), [Pt(II)Cl(2)(Glc-pyta)] (5), and [Pd(II)Cl(2)(Glc-pyta)] (6), were prepared and characterized by mass spectrometry, elemental analysis, (1)H- and (13)C-NMR, IR as well as UV/VIS spectroscopy, where AcGlc-pyta and Glc-pyta denote 2-[4-(pyridin-2-yl)-1H-1,2,3-triazol-1-yl]ethyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside (1) and 2-[4-(pyridin-2-yl)-1H-1,2,3-triazol-1-yl]ethyl β-D-glucopyranoside (2), respectively. The solid-state structure of complex 6 was determined by single-crystal X-ray-diffraction analysis. These complexes exhibited in vitro cytotoxicity against human cervix tumor cells (HeLa) though weaker than that of cisplatin.

The ether coordination of the oxygen atom to the copper(II) center supported by dipicolylamine (DPA)-derived ligands,N-[2-(2-pyridylmethyloxy)ethyl]-N,N-bis(2-pyridylmethyl)amine (LPy), N-[2-(2-quinolylmethyloxy)ethyl]-N,N-bis(2-pyridylmethyl)amine (LQ), N-[3-(2-pyridylmethyloxy)-1-propyl]-N,N-bis(2-pyridylmethyl)amine (L′Py), N-{2-[1-(2-pyridyl)ethyloxy]ethyl}-N,N-bis(2-pyridylmethyl)amine (LPy*1), N-[2-(2-pyridylmethyloxy)-1-propyl]-N,N-bis(2-pyridylmethyl)amine (LPy*2), and N-[2-(carboxymethyloxy)ethyl]-N,N-bis(2-pyridylmethyl)amine (HLCOO), have been examined. The factors that facilitate the coordination of the ether oxygen atom of these ligands to the copper center and the control of chirality around the copper-coordinated oxygen atom are discussed. The copper center exhibits a pentacoordinate geometry with these ligands, as evidenced by X-ray crystallography. The steric effect of the quinoline ring in the LQ complex prevents the coordination of a perchlorate anion to the copper center, which affords the pentacoordinate divalent complex with a shorter copper–oxygen bond than that for the corresponding pyridine ligand (LPy). The six-membered chelate in the L′Py complex also exhibits a shorter Cu–O distance. The conformation of the oxygen atom of the LPy complex is unstable because of fast lone pair inversion, but this inversion is prevented for the complexes with chiral ligands, LPy*1 and LPy*2. Upon chelation to the metal center, the HLCOO ligand forms a pentacoodinate monomer complex that further affords a 1-D polymer structure. With respect to the oxygen chirality, the water content of the solvent governs the formation of either a homochiral polymer (R-R-R-R- or S-S-S-S-) or an alternative chirality polymer (R-S-R-S-). In this case, the isomers with respect to the oxygen chirality were separated and characterized.

The crystal structures of salt 8, which was prepared from (R)-2-methoxy-2-(2-naphthyl)propanoic acid ((R)-MβNP acid, (R)-2) and (R)-1-phenylethylamine ((R)-PEA, (R)-6), and salt 9, which was prepared from (R)-2-methoxy-2-(1-naphthyl)propanoic acid ((R)-MαNP acid, (R)-1) and (R)-1-(p-tolyl)ethylamine ((R)-TEA, (R)-7), were determined by X-ray crystallography. The MβNP and MαNP anions formed ion-pairs with the PEA and TEA cations, respectively, through a methoxy-group-assisted salt bridge and aromatic CH⋅⋅⋅π interactions. The networks of salt bridges formed 2(1) columns in both salts. Finally, (S)-(2E,6E)-(1-(2) H(1) )farnesol ((S)-13) was prepared from the reaction of (2E,6E)-farnesal (11) with deuterated (R)-BINAL-H (i.e., (R)-BINAL-D). The enantiomeric excess of compound (S)-13 was determined by NMR analysis of (S)-MαNP ester 14. The solution-state structures of MαNP esters that were prepared from primary alcohols were also elucidated.

Twelve [ReIL(CO)3]n+ complexes with various carbohydrate-pendant ligands L have been prepared and their uptake into HeLa S3 cells were investigated. The ligand library includes: (i) glucose/galactose as the carbohydrate group; (ii) bis(2-pyridylmethyl)amine (DPA), bis(2-quinolylmethyl)amine (DQA), or N-(2-pyridylmethyl)glycine (NPG) as the metal binding component; and (iii) an ethylene chain as a linker between the metal binding site and the O/C-glycosides. Microwave induced plasma mass spectroscopy (MIP-MS) measurements revealed that all complexes were extensively incorporated into the HeLa cells over a 24 h period, and the DQA complexes showed the highest uptake of all the complexes in the series. However, in comparison to the corresponding Re complexes without the pendant carbohydrate functions (prepared with the related ligands LDPA, LDQA, and LNPG), only the NPG complexes exhibited carbohydrate enhanced cellular uptake. Considering their water solubility and cellular uptake properties, the NPG complexes containing an O-glycoside group (L1 and L′1) are the best candidates for enhancing cellular uptake of metal ions. Microscopic analysis with PC-12 cells in the presence of thefluorescent complex [Re(L′7)(CO)3]Cl, revealed that the complex stays in the cell cytosol and cannot penetrate into the nucleus.

The ether oxygen coordination to the zinc center in the complexes with dipicolylamine (DPA)-derived ligands, N-(2-methoxyethyl)-N,N-bis(2-pyridylmethyl)amine (L), N-(3-methoxypropyl)-N,N-bis(2-pyridylmethyl)amine (L′), and N-{3-(2-pyridylmethyloxy)propyl}-N,N-bis(2-pyridylmethyl)amine (LPy) has been discussed. Upon chelation of the oxygen atom, L forms a five-membered chelate ring with respect to the 2-aminoethyl ether moiety whereas L′ forms a six-membered chelate in 3-aminopropyl ether unit. This difference was highlighted by the crystal structures of ZnCl2 complexes, in which [Zn(L)Cl2] (1) exhibited ether oxygen coordination but [Zn(L′)Cl2] (2) had the ether oxygen non-coordinated. The terminal pyridyl group of LPy facilitates the ether oxygen atom coordination via a metal binding from the basal plane trans to the aliphatic nitrogen.