This paper describes preliminary results in the design, construction, and characterization of cobalt(Il) porphyrins derivatized with alkanethiol appendages. The use of the thiol appendages leads to the formation of a chemisorbed monolayer of the corresponding thiolate at gold electrodes. Our findings suggest that this approach may serve as a beginning for fabricating electrocatalytic monolayers with a preselected architecture through the manipulation of the number and location of the appendages. Voltammetric data indicate that monolayers from both I(Co) and II(Co) catalyze the two-electron reduction of 0 2 to H20 2• The monolayer from I(Co), however, has a lower electrocatalytic activity. Infrared, X-ray photoelectron, and visible spectroscopic data are presented that argue the difference in reactivity arises from a difference in interfacial architecture. The results from attempts to metalate monolayers from I(Hz) and II(H2) support this interpretation. Findings are also reported that indicate the preparation of mixed monolayers (e.g., twocomponent mono layers from I(Co) and CHs(CH2)aSH) may prove valuable to this area of research.

A series of mono-, bis-, and tetrakisporphyrin assemblies was synthesized from 5-(ppyridyl)-10,15,20-triphenylporphyrin, (pyPP)H2, 5-(p-pyridyl)-10,15,20-tri(p-tolyl)porphyrin, (pyTP)H2, (pyPP)Zn, (pyTP)Zn, and Pt(II) and Pd(II) complexes. Porphyrin subunits assemble around the central metal ions through the pyridyl group. Treating trans-Pd(DMSO)2Cl2 with 2 equiv of the pyridyl porphyrins resulted in the formation of trans-bisporphyrin assemblies Pd[(pyPP)H2]2Cl, Pd[(pyTP)H2]2Cl2, Pd[(pyPP)Zn]2Cl2, and Pd[(pyTP)Zn]2Cl2. Treating cis-Pt(DMSO)2Cl2 with 1 equiv of each pyridylporphyrin produced the cis-monoporphyrin complexes Pt(DMSO)[(pyPP)H2]Cl2, Pt(DMSO)[(pyTP)H2]Cl2, Pt(DMSO)[(pyPP)Zn]Cl2, and Pt(DMSO)[(pyTP)Zn]Cl2. The treatment of Pt(DMSO)(pyPOR)Cl2 with one more equiv of pyridylporphyrin resulted in the formation of cisbisporphyrin assemblies, Pt[(pyPP)H2]2Cl2, Pt[(pyTP)H2]2Cl2, Pt[(pyPP)Zn]2Cl2, and Pt[(pyTP)Zn]2Cl2. Also, the reaction of Pt(DMSO)(pyPOR)Cl2 and 4-pyridyl-4'-methylpyridinium iodide (MQ+I-) afforded cis-porphyrin−Pt−viologen assemblies. Treatment of M(DPPP)(OTf)2 (M = Pt, Pd; DPPP = 1,3-bis(diphenylphosphino)propane; OTf = triflate anion) with 2 equiv of pyridylporphyrin resulted in cis-bisporphyrin assemblies [M(DPPP)[(pyPOR)H2]2](OTf)2 and [M(DPPP)[(pyPOR)Zn]2(OTf)2. Synthesis of tetrakisporphyrin assemblies [M{(pyTP)H2}4]X2 (M = Pt, Pd; X = BF4, OTf) was accomplished by the reaction of [M(CH3CN)4]X2 with (pyTP)H2. Solution 1H NMR studies show that the four porphyrins are equivalent and that the central metals have square planar geometry. The crystal structure of [Pd(DPPP){(pyTP)H2}2](OTf)2 was determined by single-crystal X-ray diffraction analysis (monoclinic,

A series of thiol-derivatized porphyrins and the corresponding cobalt and zinc complexes were synthesized from 5-(p-aminophenyl)-10,15,20-triphenylporphyrin ( H 2 TPP - NH 2), and 5α,15α-bis(o-aminophenyl)porphyrin ( H 2 DPE - ( NH 2)2). These derivatized porphyrins have a different number of thiol appendages attached via amide linkages at different locations. The thiol-derivatized porphyrins made from H 2 TPP - NH 2, H 2 TPP - NHC ( O )( CH 2) n SH ( n = 2, 4, 5, 10), have one alkyl-thiol appendage attached to the porphyrin through an amide linkage on the p-aminophenyl position. The derivatives made from H 2 DPE -( NH 2)2 have two alkyl-thiol appendages attached to the porphyrin through amide linkages on the o-aminophenyl positions on the same face of the porphyrin ring. These thiol-derivatized porphyrins are important adsorbates for the preparation of thiol–porphyrin monolayers on gold.

No abstract

Calix[4]arenes, or endo-calix [4]arenes, 1 have been extensively studied for the past several decades, 1 but exocalix [4]arenes 2 have only recently attracted much attention. [2][3][4] With respect to structure, an exo-calixarene, having the OH groups on the "upper rim" of the bowlshaped molecules, is actually more similar to a resorcinarene (3a) 5 or cavitand (3b) 5 than to the corresponding endo-isomer. We report here the preparation of a tetra-(propyl-substituted) exo-calix [4]arene and a study of the conformational properties of it and some covalentlylinked derivatives. Experimental SectionGeneral. All reagents used were analytical grade. DMF, CH2Cl2, and CHCl3 were distilled from CaH2. 1 H NMR spectra were recorded on a Varian VXR 300 MHz or on a Varian XL400 spectrometer. Mass spectra and high-resolution mass spectra were obtained at the Mass Spectrometry Laboratory for Biotechnology at the North Carolina State University in Raleigh. Elemental analyses were performed by Atlantic Microlabs, Norcross, GA. 2,2-Bis[4′-(allyloxy)phenyl]propane (4b).Bisphenol A (235 g, 1.00 mol), allyl chloride (330 mL, 4.00 mol), potassium carbonate (276 g, 2.00 mol), sodium iodide (6.00 g, 0.040 mol), and absolute ethanol (1.50 L) were added to a 3 L three-necked round-bottomed flask. The mixture was allowed to reflux for 24 h under argon, cooled to ambient temperature, and filtered to remove solid material. The solvent was evaporated under reduced pressure to give a brown liquid (301 g, 98%). 1 H NMR (CDCl3): δ 7.12 (dd, 4H,