Kristin Bowman Mertes

A binucleating “accordian” tetrapyrrole macrocycle

Abstract The synthesis of a side-by-side binucleating porphyrin-related ligand has been accomplished via a Schiff base template-assisted condensation of a 5,5′-diformyldipyrromethane and 1,3-propanediamine.

Potential ATPase mimics by polyammonium macrocycles: Criteria for catalytic activity

Abstract A series of polyammonium macrocycles, ranging in size from the 18-membered ring [18]aneN6 to the 36-membered [36]aneN12 were examined as potential ATPase mimics. The rates of hydrolysis of ATP were followed at pH 3.0 and 7.0 using 31P NMR and HPLC techniques. Stability constants as a function of degree of protonation, distribution curves for the ligands as a function of pH, and distribution curves for the mixed species of nucleotides, inorganic phosphate, and macrocycle were also determined. All of the macrocycles catalyzed the hydrolysis of ATP to some extent compared to noncatalyzed hydrolysis. A critical dependence on macrocyclic ring size was observed, with [21]aneN7 being the best catalyst at both pHs. Stability constants of the complexes formed between the phosphate species and macrocycle increase with increasing degree of protonation and decreasing ring size. The trend in stability constants for phosphate species was found to be PO43− > P2O74− > ATP4− > ADP3− > AMP2− for a given degree of protonation. The crystal structure of tetraprotonated [21]aneN7 was determined. The compound N7C14Cl4H41O crystallizes in the monoclinic space group P21 (#4) with unit cell dimensions a = 7.472(1), b = 19.480(2), c = 8.3638(9) A , β = 100.38(1)o, and V = 1197.4(3) A 3 . The structure was solved by direct methods and refined using full-matrix least-squares techniques to give a final R = 0.041 and Rw = 0.055.

A convenient synthesis of macrocyclic lactams

Abstract A facile method is described for the synthesis of macrocyclic lactams using dicarboxylic acids and diamines directly in the presence of diphenylphosphoryl azide.

Structural Aspects of the Dephosphorylation of Adenosine Triphosphate Catalyzed by Polyammonium Macrocycles

Abstract Four polyammonium macrocycles were synthesized and characterized: two with 21-membered rings and differing numbers of oxygen and nitrogen heteroatoms, [21]N6O (1) and [21]N5O2 (2), and two with bipyridine incorporated into the ring, [24]N4O2bipy (3) and [27]N3O2bipy (4). Their ability to catalyze the dephosphorylation of adenosine triphosphate was examined. It was found that ring size plays a crucial role in the catalytic ability of the macrocycles, with the 21-membered rings being superior to larger macrocycles. Also, rates of dephosphorylation were found to increase with increasing number of nitrogen atoms in the ring. For two of the macrocycles, crystal structures were determined. Macrocycle 2 crystallizes in the tricliriic space group PI, a = 10.692(1), b = 17.037(2), c = 8.1952(8)A, a = 92.550(9), β = 100.816(9), γ = 106.77(1)°, V = 1396.1(3) A3; the structure was solved to R = 0.089 and R w = 0.098. Macrocycle 4 crystallizes in the monoclinic space group P21/n, a = 14.589(1), b = 15.427(1),...

[Co(terpy)2] [NO3]2ṡ2H2O: Tetragonal Compression with Elongated Equatorial Bonds

Abstract The crystal and molecular structure of the dihydrate of [Co(terpy) 2 ] [NO 3 ] 2 was determined. The complex crystallizes in the tetragonal space group I 4/ a with a = 12.408(2) and c = 38.867(6) A. The structure was refined using 2272 independent reflections to a final R = 0.058 and R w = 0.081. The structure consists of Co(terpy) 2 2+ cations, disordered NO 3 − anions, and two watet molecules of crystallization. The cation exhibits compression along the molecular z axis along with significant elongation along the x and y axes with almost identical bond lengths (2.189(3) and 2.180(3) A). These are the longest CoN bonds observed in a cobalt(lI) bis- terpyridine complex to date.

Strategy for the synthesis of unsymmetrical N-substituted polyazamacrocycles

Abstract A convergent route is described for the preparation of unsymmetrical N-substituted polyammonium macrocycles that is potentially applicable for the synthesis of a wide variety of macrocycles of differing ring size and heteroatom substitution.

Reactions of formyl phosphate with linear and macrocyclic polyamines

Abstract The aminolysis of formyl phosphate by both linear and macrocyclic polyamines at pH 7 and 5°C was examined and found to proceed primarily by C-O cleavege to give the N-formylated amines. In the presence of excess bromide ion (ionic strength 0.3) the reaction was second-order with rate constants ranging from 7.1 to 12 liter m −1 min−1 for the macrocyclic amines 1,4,7,13,16,19-hexaaza-10,22-dioxacyclotetraeicosane ([24]N6O2, 1) and 1,4,7,10,13,16-hexaazacyclooctadecane ([18]N6, 4) and the linear amines 1,4,7,10,13-pentaazatridecane ([L]N5, 5) and 1,4,7,10-tetraazadecane ([L]N4, 6). In the absence of excess bromide ion the reaction was first-order with a rate constant of 0.30 min−1 for 1 and ranged from 0.26 to 0.54 min−1 for the other amines. The addition of a stable substrate analog (phosphonoacetaldehyde) to the reaction significantly decreased the rate of aminolysis. The reaction is proposed to proceed through a supramolecular complex of polyprotonated polyamine and formyl phosphate with a dissociation constant less than 1 × 10−3 m . A similar complex has been proposed for the reaction of acetyl phosphate and 1 which gives P-O, not C-O, cleavage. The rate as a function of pH for the aminolysis of formyl phosphate by 1 is reasonably constant in the mid-pH region and the rate decreases at the extremes of pH 4 and 9. The results of this study more fully characterize the activation of formate in neutral aqueous media by adenosine 5′-triphosphate in the presence of 1, a model for the reaction catalyzed by the enzyme N10-formyltetrahydrofolate synthetase for which formyl phosphate is a proposed intermediate.

Synthesis, characterization, and pressure dependence of conductivity for a partially‐oxidized tetra‐aza macrocyclic palladium complex

The synthesis and characterization of the I2 oxidation product of a tetra‐aza macrocyclic complex of Pd (II) is described. The product is formulated as [Pd (TAAB)] [I3]2.7 where TAAB is tetrabenzo [b, f, j, n] [1, 5, 9, 13] tetra‐azacyclohexadecine. The presence of I3 was confirmed by Raman and far‐infrared spectroscopy. Electrical conductivity measurements for pressed powder samples using a diamond‐anvil pressure cell showed an unusually large pressure dependence.

The mechanism of formyl phosphate hydrolysis

Abstract The hydrolysis of formyl phosphate was studied in unbuffered and buffered solutions. In the absence of buffer the rate constant (8.8 × 10 −3 min −1 at 25°C and pH 7) varies little from about pH 5 to 8 and increases dramatically at low and high pH values. At pH 7 the hydrolysis appears to proceed via two mechanisms, nucleophilic attack on the carbonyl carbon and a mechanism involving PO bond cleavage. This is based on the facts that the reaction proceeds 45% by CO bond cleavage and 55% by PO bond cleavage (shown using H 2 18 O) ; there is a solvent isotope effect of 1.6; the Δ S ‡ (−11.8 e.u.) is intermediate between that expected for a unimolecular and a bimolecular reaction; the reaction rate is affected by organic solvent and buffer. At pH 1 and 11 the mechanism is entirely nucleophilic substitution at the carbonyl since the reaction proceeds 100% by CO cleavage, and the Δ S ‡ (−21.3 and −25.5 e.u.) is that expected for a bimolecular reaction. In the presence of Tris and glycine the formyl phosphate disappearance is accompanied by formylation of the primary amines with a 100% yield in the case of glycine. Imidazole and pyridine also catalyze formyl phosphate breakdown. In the former case the reaction proceeds primarily by CO cleavage, but no formylated product was observed. Differences in the hydrolyses of formyl phosphate and acetyl phosphate are discussed.

The crystal structure of triphenylselenonium isothiocyanate

Abstract Three dimensional X-ray crystal structure analysis shows that triphenylselenonium isothiocyanate consists of discrete ion pairs in the solid state with each pair having an Se-N contact (3.197(4)A) and SeC(NCS) contact (3.260(5)A) significantly shorter than the respective van der Waals distance. These short distances are accompanied by acute SeNC (83.0(3)°) and SeCN (76.8(3)°) angles, and suggest a weak interaction between the triphenylselenonium cation and the π-electron system of isothiocyanate anion. Ph 3 Se(NCS) is neither isomorphous nor isostructural with Ph 3 Te(NCS). Refinement of the structure, based on 3126 reflections collected by automatic diffractometry, converged to a conventional R factor of 5.5% and a weighted R factor of 5.2%. Crystal data for Ph 3 Se(NCS) are as follows: a = 12.417(4)A, b = 11.556(5)A, c = 12.633(3)A, β = 113.17(2)°, V = 1666A 3 (23 ± 2°C) and Z = 4; space group P2 1 /c.