Frank R. Fronczek

Louisiana State University, Baton Rouge, Louisiana, United States

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Publications (782)1212.72 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Pr1.33Pt4Ga10 single crystals are prepared from the elements using excess Ga as flux (alumina crucible in evacuated silica ampoule, 1150 °C, 4 h, 2; ≈10% yield).
    ChemInform 11/2014; 45(46).
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    ABSTRACT: New mononuclear amidine complexes, fac-[Re(CO)3(Me2bipy)(HNC(CH3)(pyppz))]BF4 [(4,4'-Me2bipy (1), 5,5'-Me2bipy (2), and 6,6'-Me2bipy (3)] (bipy = 2,2'-bipyridine), were synthesized by treating the parent fac-[Re(I)(CO)3(Me2bipy)(CH3CN)]BF4 complex with the C2-symmetrical amine 1-(4-pyridyl)piperazine (pyppzH). The axial amidine ligand has an exposed, highly basic pyridyl nitrogen. The reaction of complexes 1-3 with a B12 model, (py)Co(DH)2Cl (DH = monoanion of dimethylglyoxime), in CH2Cl2 yielded the respective dinuclear complexes, namely, fac-[Re(CO)3(Me2bipy)(μ-(HNC(CH3)(pyppz)))Co(DH)2Cl]BF4 [(4,4'-Me2bipy (4), 5,5'-Me2bipy (5), and 6,6'-Me2bipy (6)]. (1)H NMR spectroscopic analysis of all compounds and single-crystal X-ray crystallographic data for 2, 3, 5, and 6 established that the amidine had only the E configuration in both the solid and solution states and that the pyridyl group is bound to Co in 4-6. Comparison of the NMR spectra of 1-3 with spectra of 4-6 reveals an unusually large "wrong-way" upfield shift for the pyridyl H2/6 signal for 4-6. The wrong-way H2/6 shift of (4-Xpy)Co(DH)2Cl (4-Xpy = 4-substituted pyridine) complexes increased with increasing basicity of the 4-Xpy derivative, a finding attributed to the influence of the magnetic anisotropy of the cobalt center on the shifts of the (1)H NMR signals of the pyridyl protons closest to Co. Our method of employing a coordinate bond for conjugating the fac-[Re(I)(CO)3] core to a vitamin B12 model could be extended to natural B12 derivatives. Because B12 compounds are known to accumulate in cancer cells, such an approach is a very attractive method for the development of (99m)Tc and (186/188)Re radiopharmaceuticals for targeted tumor imaging and therapy.
    Inorganic chemistry. 10/2014;
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    ABSTRACT: Catalytic hydrogenation of dibenzyl 5-dipyrroketone-2,9-dicarboxylates followed by decarboxylative iodination affords a 2,9-diiododipyrroketone which gives a 2,5,9-trichlorodipyrromethene hydrochloride after nucleophilic addition/elimination, with adventitious chloride to replace the two iodide groups. Treatment with BF3.Et2O gives a 3,5,8-trichloro-BODIPY that readily undergoes regioselective Stille coupling at the 8-position, or homo/mixed couplings at the 3,8- or 3,5 and 8-positions. Stepwise and controlled replacement of the 3,5 and 8 chlorine atoms using Stille reagents results in formation of a completely unsymmetrical trisubstituted BODIPY. Several examples of unsymmetrical BODIPYs were synthesized and characterized using this methodology. Structure features of new BODIPYs are discussed within the context of 14 new X-ray structures, and photophysical parameters of all new BODIPY compounds are reported and discussed.
    The Journal of organic chemistry. 09/2014;
  • Tetrahedron Letters 09/2014; 55(39):5361–5364. · 2.40 Impact Factor
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    ABSTRACT: A new binucleating tetraphosphine ligand, rac- and meso-(Et2P-1,2-C6H4)P(Ph)CH2(Ph)P(1,2-C6H4PEt2) (et,ph-P4-Ph), has been synthesized. Separation and purification of the ligand diastereomers have been accomplished via column chromatography. Ni2Cl4(et,ph-P4-Ph) complexes of both diastereomers have been prepared in high yield and crystallographically characterized.
    Inorganic chemistry. 09/2014;
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    ABSTRACT: The continued proliferation of malaria throughout temperate and tropical regions of the world has promoted a push for more efficacious treatments to combat the disease. Unfortunately, more recent remedies such as artemisinin combination therapies (ACTs) have been rendered less effective due to developing parasite resistance and new drugs are required that target the parasite in the liver to support the disease elimination efforts. Research was initiated to revisit antimalarials developed in the 1940's and 1960's that were deemed unsuitable for use as therapeutic agents as a result of poor understanding of both physicochemical properties and parasitology. Structure activity studies (SAR) and structure property studies (SPR) were conducted to generate a set of compounds with the general 6-chloro-7-methoxy-2-methyl-4(1H)-quinolone scaffold which were substituted at the 3-position with a variety of phenyl moieties possessing various properties. Extensive physicochemical evaluation for the quinolone series was carried out to downselect the most promising 4(1H)-quinolones 7, 62, 66 and 67 which possessed low nanomolar EC50s against W2 and TM90-C2B as well as improved microsomal stability. Additionally, in vivo Thompson test results using P. berghei in mice showed that these 4(1H)-quinolones were efficacious for the reduction of parasitemia at >99% after 6 days.
    Journal of medicinal chemistry. 08/2014;
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    ABSTRACT: A series of tri[(p-carboranylmethylthio)tetrafluorophenyl]porphyrin conjugates of linear and branched polyamines, glucose, arginine, tri(ethylene glycol), and peptide Tyr-D-Arg-Phe-β-Ala (TAPA) were synthesized. These conjugates were investigated for their BBB permeability in human hCMEC/D3 brain endothelial cells as model, and their cytotoxicity and uptake in human glioma T98G cells. For comparison purposes, a symmetric tetra[(p-carboranylmethylthio)tetrafluorophenyl]porphyrin was also synthesized and its crystal structure was obtained. All porphyrin conjugates show low dark cytotoxicity (IC50 > 400 μM) and low phototoxicity (IC50>100 μM at 1.5 J/cm2) toward T98G cells. All conjugates were efficiently taken up by T98G cells, particularly the cationic polyamine and arginine conjugates, and localized in multiple cell organelles, including the mitochondria and lysosomes. All compounds showed relatively low in vitro BBB permeability compared with lucifer yellow, probably due to their higher molecular weight, hydrophobicity and tendency for aggregation in solutions. Among this series, the branched polyamine and TAPA conjugates showed the highest permeability coefficients, while the glucose conjugate showed the least.
    Journal of medicinal chemistry. 07/2014;
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    ABSTRACT: β-Nitrocorroles are potentially valuable platforms for the preparation of a wide range of more elaborated corrole derivatives possessing unique chemical functionalities and electronic properties. Here we report our results on the chemical manipulation of a copper 3-NO2-triarylcorrolate using different organic reactions, all involving the reduction of -NO2 to -NH2 at an early stage, followed by further transformations. By way of a β-acylated copper corrolate, a novel corrole derivative bearing an alkyl azide group on the peripheral positions was obtained and exploited in the Huisgen 1,3-dipolar cycloaddition.
    Organic & Biomolecular Chemistry 07/2014; · 3.57 Impact Factor
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    ABSTRACT: The palladium-catalyzed ortho monobromination and iodination of single E or Z geometric isomers of substituted diaryl ketoxime ethers [Ar1C(Ar2) = N–OCH3] have been accomplished in good yield (64–82% isolated yield). A minor amount of di-ortho-halogenation side product is produced in this reaction (0–10%). The aromatic ring that is halogenated is the one ‘trans’ to the OCH3 group, indicating that there is no isomerization about the C@N bond during the reaction. Further, the site of functionalization is presumably controlled by the lone pair electrons on nitrogen. This study is the first to demonstrate the ability of the geometry of the oxime ether group to target the functionalization of only one aromatic ring when there are two aromatic rings directly attached to the carbon of the C@N bond of the oxime ether. Electron-withdrawing substituents on either ring decrease reaction rate and diminish the amount of di-ortho-bromination side product.
    Tetrahedron Letters 07/2014; · 2.40 Impact Factor
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    ABSTRACT: (LaxCe1−x)1.33Pt4Ga10 (0 ⩽ x ⩽ 1), synthesized with excess Ga flux, crystallize in the P63/mmc space group, Z = 1, with lattice parameters a = b ∼ 4.3 and c ∼ 16.5 Å for the entire range of the solid solution. Single-crystal diffraction and electron microscopy methods show that La substitution within the solid solution does not lead to systematic decrease in unit cell dimensions. The crystal structure of (LaxCe1−x)1.33Pt4Ga10 (0 ⩽ x ⩽ 1) can be viewed as a combination of RE2Ga3 (A) and double Pt2Ga4 (B) layers stacked along the c axis in an ABAB sequence. Ce1.33Pt4Ga10 exhibits a large negative Weiss constant, θW = −87.2 K, but does not reveal any signature of magnetic ordering. An examination of zero-field-cooled and field-cooled magnetization curves and AC susceptibility at low temperatures excludes a possible formation of spin-glass state down to 1.8 K. These findings support an earlier suggestion that Ce1.33Pt4Ga10 might exhibit non-Fermi liquid behavior.
    Journal of Alloys and Compounds 07/2014; 600:193–198. · 2.73 Impact Factor
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    ABSTRACT: DABCO (1,4-diazabicyclo[2.2.2]octane) catalyzed a multicomponent reaction using the starting precursor 2,3,4,9-tetrahydro-1H-carbazol-1-one, malononitrile, and aromatic/heteroaromatic aldehyde.
    Synthetic Communications 06/2014; 44(12). · 1.06 Impact Factor
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    ABSTRACT: Novel substituted 2,3-dihydrobenzofuran-7-carboxamide (DHBF-7-carboxamide) and 2,3-dihydrobenzofuran-3(2H)-one-7-carboxamide (DHBF-3-one-7-carboxamide) derivatives were synthesized and evaluated as inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1). A structure-based design strategy resulted in lead compound 3 (DHBF-7-carboxamide; IC50 = 9.45 µM). To facilitate synthetically feasible derivatives, an alternate core was designed, DHBF-3-one-7-carboxamide (36, IC50 = 16.2 μM). The electrophilic 2-position of this scaffold was accessible for extended modifications. Substituted benzylidene derivatives at the 2-position were found to be the most potent, with 3',4'-dihydroxybenzylidene 58 (IC50 = 0.531 µM) showing a 30-fold improvement in potency. Various heterocycles attached at the 4'-hydroxyl/4'-amino of the benzylidene moiety resulted in significant improvement in inhibition of PARP-1 activity (e.g., compounds 66-68, 70, 72 and 73; IC50 values from 0.718 to 0.079 µM). Compound 66 showed selective cytotoxicity in BRCA2-deficient DT40 cells. Crystal structures of three inhibitors (compounds (-)-13c, 59 and 65) bound to a multi-domain PARP-1 structure were obtained, providing insights into further development of these inhibitors.
    Journal of medicinal chemistry. 06/2014;
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    ABSTRACT: Hematotoxicity in individuals genetically deficient in glucose-6-phosphate dehydrogenase (G6PD) activity is the major limitation of primaquine (PQ), the only antimalarial drug in clinical use for treatment of relapsing P. vivax malaria. PQ is currently clinically used in its racemic form. A scalable procedure was developed to resolve racemic PQ thus providing pure enantiomers for the first time for detailed preclinical evaluation and potentially for clinical use. These enantiomers were compared for antiparasitic activity in several mouse models, and also for general and hematological toxicities in mice and dogs. (+)-(S)-PQ showed better suppressive and causal prophylactic activity than (-)-(R)-PQ in mice infected with Plasmodium berghei. Similarly, (+)-(S)-PQ was a more potent suppressive agent than (-)-(R)-PQ in a mouse model of Pneumocystis carinii pneumonia. However, at higher doses (+)-(S)-PQ also showed more systemic toxicity to mice. In Beagle dogs (+)-(S)-PQ caused more methemoglobinemia and was toxic at 5 mg/kg/day orally for 3 days, while the (-)-(R)-PQ was well tolerated. In a novel mouse model of hemolytic anemia associated with human glucose-6-phosphate dehydrogenase (G6PD) deficiency, it was also demonstrated that (-)-(R)-PQ was less hemolytic compared to (+)-(S)-PQ to the G6PD deficient human red cells engrafted in the NOD-SCID mice. All these data suggest that while (+)-(S)-PQ shows greater potency in terms of antiparasitic efficacy in rodents, it is also more hematotoxic than (-)-(R)-PQ in mice and dogs. Activity and toxicity differences of PQ enantiomers in different species can be attributed to their different pharmacokinetic and metabolic profiles. Taken together, these studies suggest that (-)-(R)-PQ may have a better safety margin than the racemate in human.
    Antimicrobial Agents and Chemotherapy 06/2014; · 4.57 Impact Factor
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    ABSTRACT: Brevianes are a family of bioactive meroterpenoids originally described in fungi of the family Penicillium. These compounds have attracted a great deal of interest not only because of their unusual skeleton, suggesting a mixed mevalonate and polyketide biogenetic pathway, and their unusual oxa-spiro ring fused to a α-pyrone, but also because of the bioactivities shown by many members of this family.
    Pest Management Science 05/2014; · 2.74 Impact Factor
  • ChemInform 05/2014; 45(18).
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    ABSTRACT: A number of 1,2,4-oxadiazolone and mercapto nitro benzimidazole derivatives containing 1,2,4-oxadiazole and hydantoin moieties have been prepared, and their structures were identified by means of spectral/physical characteristics including X-ray diffraction data.
    Molecular Diversity 05/2014; · 2.86 Impact Factor
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    ABSTRACT: Two new diterpene glycosides in addition to five known glycosides have been isolated from a commercial extract of the leaves of Stevia rebaudiana. Compound 1 (rebaudioside KA) was shown to be 13-[(O-β-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid 2-O-β-d-glucopyranosyl-β-d-glucopyranosyl ester and compound 2, 12-α-[(2-O-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid 2-O-β-d-glucopyranosyl ester. Five additional known compounds were identified, rebaudioside E, rebaudioside M, rebaudioside N, rebaudioside O, and stevioside, respectively. Enzymatic hydrolysis of stevioside afforded the known ent-kaurane aglycone 13-hydroxy-ent-kaur-16-en-19-oic acid (steviol) (3). The isolated metabolite 1 possesses the ent-kaurane aglycone steviol (3), while compound 2 represents the first example of the isomeric diterpene 12-α-hydroxy-ent-kaur-16-en-19-oic acid existing as a glycoside in S. rebaudiana. The structures of the isolated metabolites 1 and 2 were determined based on comprehensive 1D- and 2D-NMR (COSY, HSQC, and HMBC) studies. A high-quality crystal of compound 3 has formed, which allowed the acquisition of X-ray diffraction data that confirmed its structure. The structural similarities between the new metabolites and the commercially available stevioside sweeteners suggest the newly isolated metabolites should be examined for their organoleptic properties. Accordingly rebaudiosides E, M, N, O, and KA have been isolated in greater than gram quantities.
    Journal of Natural Products 04/2014; · 3.29 Impact Factor
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    ABSTRACT: X-ray crystal structure study of cocrystallites of buckycatcher (2, C60H28) demonstrates a remarkable versatility of the molecular clip to accommodate guest molecules of various sizes and shapes. As demonstrated by the B97-D calculations, concave–concave conformation of the clip seems to be preferred for the gas-phase 1:1 inclusion complexes of 2 with a series of potential guests. However, the unprecedented concave–convex conformations were found in two of the reported solvates [i.e., 2·0.75(p-xylene) and 2·2PhNO2]. Three of the studied inclusion complexes with the highest calculated gas-phase binding energies (1,3,5-trinitrobenzene@2, and the previously reported C60@2 and C70@2) exhibit the analogous 1:1 supramolecular arrangements in the crystal state. On the other hand, p-xylene and PhNO2 solvates as well as DDQ/MeCN cocrystallite exhibit quite different stoichiometries and supramolecular arrangements, presumably enforced by the crystal packing forces. Dramatic variations of the intercentroid distances between the central five-membered rings of the corannulene pincers in the inclusion complexes (from 7.87 to 11.51 Å) expose an impressive flexibility of the buckycatcher tether.
    Crystal Growth & Design 04/2014; 14(5):2633–2639. · 4.69 Impact Factor
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    ABSTRACT: The phenyl-iron complex of 5,10,15-tritolylcorrole was prepared by reaction of the starting chloro-iron complex with phenylmagnesium bromide in dichloromethane. The organometallic complex was fully characterized by a combination of spectroscopic methods, X-ray crystallography, and density functional theory (DFT) calculations. All of these techniques support the description of the electronic structure of this phenyl-iron derivative as a low-spin iron(IV) coordinated to a closed-shell corrolate trianion and to a phenyl monoanion. Complete assignments of the (1)H and (13)C NMR spectra of the phenyl-iron derivative and the starting chloro-iron complex were performed on the basis of the NMR spectra of the regioselectively β-substituted bromo derivatives and the DFT calculations.
    Inorganic Chemistry 04/2014; · 4.59 Impact Factor
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    ABSTRACT: Symmetric dipyrrylketones 1 a,b were synthesized in two steps from the corresponding α-free pyrroles, by reaction with thiophosgene followed by oxidative hydrolysis under basic conditions. The dipyrrylketones produced the corresponding 5-chloro-dipyrrinium salts or 5-ethoxy-dipyrrins on reaction with phosgene or Meerwein’s salt, respectively. Boron complexation of the dipyrrins afforded the corresponding 8-functionalized BODIPYs (borondipyrromethenes) in high yields. The 5-chloro-dipyrrinium salts reacted with methoxide or ethoxide ions to produce monopyrrole esters, presumably via a 5,5-dialkoxy-dipyrromethane intermediate. In contrast, 8-chloro-BODIPYs underwent a variety of nucleophilic substitutions of the chloro group in the presence of alkoxide ions, Grignard reagents, and thiols. In the presence of excess alkoxide or Grignard reagent, at room temperature or above, substitution at the boron center also occurred. The 8-chloro-BODIPY was a particularly useful reagent for the preparation of 8-aryl-, 8-alkyl-, and 8-vinyl-substituted BODIPYs in very high yields, using Pd0-catalyzed Stille cross-coupling reactions. The X-ray structures of eleven BODIPYs and two pyrroles are presented, and the spectroscopic properties of the synthesized BODIPYs are discussed.
    Chemistry 03/2014; · 5.93 Impact Factor

Publication Stats

2k Citations
1,212.72 Total Impact Points

Institutions

  • 1984–2014
    • Louisiana State University
      • Department of Chemistry
      Baton Rouge, Louisiana, United States
  • 2013
    • University of Southern Mississippi
      • Department of Chemistry and Biochemistry
      Hattiesburg, MS, United States
    • Erciyes Üniversitesi
      • Department of Physics
      Kayseri, Kayseri, Turkey
    • Zhejiang Normal University
      • College of Chemistry and Life Sciences
      Jinhua, Zhejiang Sheng, China
    • Southwest University
      Kenner, Louisiana, United States
  • 2004–2013
    • Jackson State University
      • Department of Chemistry and Biochemistry
      Jackson, MS, United States
    • Louisiana College
      Louisiana, United States
  • 2003–2013
    • University of Louisiana at Monroe
      • Department of Chemistry
      Louisiana, United States
    • University of Rome Tor Vergata
      • • Dipartimento di Scienze e Tecnologie Chimiche
      • • Dipartimento di Scinze e Tecnologie Chimiche
      Roma, Latium, Italy
  • 2012
    • Mississippi State University
      • Department of Chemistry
      Starkville, MS, United States
    • Anyang Normal University
      Chang-te, Henan Sheng, China
    • Manchester Metropolitan University
      • Division of Chemistry and Environmental Science
      Manchester, ENG, United Kingdom
  • 2011–2012
    • Bharathiar University
      • Department of Chemistry
      Coimbatore, State of Tamil Nadu, India
    • University of Louisiana at Lafayette
      • Department of Chemistry
      Lafayette, LA, United States
    • Royal College of Surgeons in Ireland
      • Department of Pharmaceutical & Medicinal Chemistry
      Dublin, L, Ireland
  • 2010–2012
    • University of Texas at San Antonio
      • Department of Chemistry
      San Antonio, TX, United States
    • University of Oklahoma
      • Department of Chemistry and Biochemistry
      Norman, Oklahoma, United States
    • Moi University
      • Department of Chemistry and Biochemistry
      Nairoba, Nairobi Area, Kenya
  • 2002–2012
    • University of Mississippi
      • • National Center for Natural Products Research
      • • Department of Pharmacognosy
      • • School of Pharmacy
      Oxford, MS, United States
    • Case Western Reserve University
      • Department of Chemistry
      Cleveland, OH, United States
    • University of West London
      Londinium, England, United Kingdom
  • 2010–2011
    • University of South Florida
      • Department of Chemistry
      Tampa, FL, United States
  • 2005–2011
    • Abant İzzet Baysal Üniversitesi
      • Department of Chemistry
      Bolu, Bolu, Turkey
    • McNeese State University
      • Department of Chemistry
      Lake Charles, LA, United States
    • La Salle University
      • Department of Chemistry and Biochemistry
      Philadelphia, Pennsylvania, United States
  • 2009
    • The University of Tampa
      Tampa, Florida, United States
    • United States Department of Agriculture
      • Agricultural Research Service (ARS)
      Washington, D. C., DC, United States
  • 2008
    • Mississippi College
      Clinton, Michigan, United States
  • 1998–2008
    • University of Houston
      • Department of Chemistry
      Houston, Texas, United States
  • 2007
    • International Union of Toxicology
      Reston, Virginia, United States
  • 2005–2006
    • University of Akron
      • Department of Polymer Science
      Akron, OH, United States
  • 1990–2006
    • Universidad de Cádiz
      • • Facultad de Ciencias
      • • Department of Organic Chemistry
      Cadiz, Andalusia, Spain
  • 2003–2005
    • Virginia Polytechnic Institute and State University
      • Department of Chemistry
      Blacksburg, VA, United States
  • 2001–2002
    • Iowa State University
      • Department of Chemistry
      Ames, Iowa, United States
    • Roanoke College
      Blacksburg, Virginia, United States
  • 1987–1997
    • Universidad Nacional Autónoma de México
      • Institute of Chemistry
      Mexico City, The Federal District, Mexico
  • 1994
    • University of Münster
      • Institut für Pharmazeutische Biologie und Phytochemie
      Münster, North Rhine-Westphalia, Germany
  • 1988
    • University of Pittsburgh
      • Department of Chemistry
      Pittsburgh, PA, United States