Synthesis,characterization, and crystal structures of organonickel(II) complexes coordinated to novel 1‐bromo‐2,6‐bis{[(λ5‐phosphanylidene)imino]methyl}benzene NCN‐pincer ligands

A novel family of four 1‐bromo‐2,6‐bis{[(λ⁵‐phosphanylidene)imino]methyl}benzene ligands has been synthesized and characterized. The phosphiniminomethyl substituents are decorated with either three phenyl groups, two phenyl and one cyclohexyl group, one phenyl and two cyclohexyl groups, or three cyclohexyl groups. Each ligand was metallated using zero‐valent nickel through an oxidative addition to form a family of organonickel(II) complexes, namely (2,6‐bis{[(triphenyl‐λ⁵‐phosphanylidene)imino]methyl}phenyl‐κ³N,C¹,N′)bromidonickel(II) dichloromethane hemisolvate, [NiBr(C₄₄H₃₇N₂P₂)]·0.5CH₂Cl₂, (2,6‐bis{[(cyclohexyldiphenyl‐λ⁵‐phosphanylidene)imino]methyl}phenyl‐κ³N,C¹,N′)bromidonickel(II) diethyl ether hemisolvate, [NiBr(C₄₄H₄₉N₂P₂)]·0.5C₄H₁₀O, (2,6‐bis{[(dicyclohexylphenyl‐λ⁵‐phosphanylidene)imino]methyl}phenyl‐κ³N,C¹,N′)bromidonickel(II), [NiBr(C₄₄H₆₁N₂P₂)], and (2,6‐bis{[(tricyclohexyl‐λ⁵‐phosphanylidene)imino]methyl}phenyl‐κ³N,C¹,N′)bromidonickel(II), [NiBr(C₄₄H₇₃N₂P₂)]. This family of complexes represents a useful opportunity to investigate the impact of incrementally changing the steric characteristics of a complex on its structure and reactivity.     

Biodegradable polymers based on renewable resources. IX. Synthesis and degradation behavior of polycarbonates based on 1,4:3,6‐dianhydrohexitols and tartaric acid derivatives with pendant functional groups

Novel polycarbonates, with pendant functional groups, based on 1,4:3,6‐dianhydrohexitols and L ‐tartaric acid derivatives were synthesized. Solution polycondensations of 1,4:3,6‐dianhydro‐bis‐O‐(p‐nitrophenoxycarbonyl)hexitols and 2,3‐di‐O‐methyl‐L ‐threitol or 2,3‐O‐isopropylidene‐L ‐threitol afforded polycarbonates having pendant methoxy or isopropylidene groups, respectively, with number average molecular weight (M_n) values up to 3.6₁ × 10⁴. Subsequent acid‐catalyzed deprotection of isopropylidene groups gave well‐defined polycarbonates having pendant hydroxyl groups regularly distributed along the polymer chain. Differential scanning calorimetry (DSC) demonstrated that all the polycarbonates were amorphous with glass transition temperatures ranging from 57 to 98 °C. Degradability of the polycarbonates was assessed by hydrolysis test in phosphate buffer solution at 37 °C and by biochemical oxygen demand (BOD) measurements in an activated sludge at 25 °C. In both tests, the polycarbonates with pendant hydroxyl groups were degraded much faster than the polycarbonates with pendant methoxy and isopropylidene groups. It is noteworthy that degradation of the polycarbonates with pendant hydroxyl groups was remarkably fast. They were completely degraded within only 150 min in a phosphate buffer solution and their BOD‐biodegradability reached nearly 70% in an activated sludge after 28 days. The degradation behavior of the polycarbonates is discussed in terms of their chemical and physical properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3909–3919, 2005     

Conformational studies on heteroleptic trifluoromethyl‐substituted phenylboranes

Organoboranes carrying electron‐withdrawing substituents are commonly used as Lewis acidic catalysts or cocatalysts in a variety of organic processes. These Lewis acids also became popular through their application in `frustrated Lewis pairs', i.e. combinations of Lewis acids and bases that are unable to fully neutralize each other due to steric or electronic effects. We have determined the crystal and molecular structures of four heteroleptic arylboranes carrying 2‐(trifluoromethyl)phenyl, 2,6‐bis(trifluoromethyl)phenyl, 3,5‐bis(trifluoromethyl)phenyl or mesityl substituents. [3,5‐Bis(trifluoromethyl)phenyl]bis[2‐(trifluoromethyl)phenyl]borane, C₂₂H₁₁BF₁₂, (I), crystallizes with two molecules in the asymmetric unit which show very similar geometric parameters. In one of the two molecules, both trifluoromethyl groups of the 3,5‐bis(trifluoromethyl)phenyl substituent are disordered over two positions. In [3,5‐bis(trifluoromethyl)phenyl]bis[2,6‐bis(trifluoromethyl)phenyl]borane, C₂₄H₉BF₁₈, (II), only one of the two meta‐trifluoromethyl groups is disordered. In [2,6‐bis(trifluoromethyl)phenyl]bis[3,5‐bis(trifluoromethyl)phenyl]borane, C₂₄H₉BF₁₈, (III), both meta‐trifluoromethyl groups of only one 3,5‐bis(trifluoromethyl)phenyl ring are disordered. [3,5‐Bis(trifluoromethyl)phenyl]dimesitylborane, C₂₆H₂₅BF₆, (IV), carries only one meta‐trifluoromethyl‐substituted phenyl ring, with one of the two trifluoromethyl groups disordered over two positions. In addition to compounds (I)–(IV), the structure of bis[2,6‐bis(trifluoromethyl)phenyl]fluoroborane, C₁₆H₆BF₁₃, (V), is presented. None of the ortho‐trifluoromethyl groups is disordered in any of the five compounds. In all the structures, the boron centre is in a trigonal planar coordination. Nevertheless, the bond angles around this atom vary according to the bulkiness and mutual repulsion of the substituents of the phenyl rings. Also, the ortho‐trifluoromethyl‐substituted phenyl rings usually show longer B—C bonds and tend to be tilted out of the BC₃ plane by a higher degree than the phenyl rings carrying ortho H atoms. A comparison with related structures corroborates the conclusions regarding the geometric parameters of the boron centre drawn from the five structures in this paper. On the other hand, CF₃ groups in meta positions do not seem to have a marked effect on the geometry involving the boron centre. Furthermore, it has been observed for the structures reported here and those reported previously that for CF₃ groups in ortho positions of the aromatic ring, disorder of the F atoms is less probable than for CF₃ groups in meta or para positions of the ring.     

Molecular recognition of nitrogen – containing bases by Zn[5,15-bis-(2,6-dodecyloxyphenyl)]porphyrin

By means of spectrophotometric titration and ¹H NMR spectroscopy, the selective binding ability of the Zn-5,15-bis-(2,6-dodecyloxyphenyl)porphyrin towards nitrogen containing organic molecules of various nature has been studied. It has been found that the presence of long alkoxy substituents at the ortho-positions of the Zn-porphyrin phenyl rings prevents the axial coordination of tertiary amines and, conversely, creates favourable conditions for binding of a primary diamine due to the presence of additional binding sites, namely the oxygen atoms of the ortho–ortho′- dodecyloxy substituents of the meso phenyl groups. The formation of stable complexes with multiple binding sites has been confirmed by DFT quantum chemical calculations and two-dimensional NMR experiments.     

Electron impact mass spectrometry of some 2,11-diaza[3.3]cyclophane derivatives

The most significant mass spectral features of thirteen title compounds are discussed with the aid of high-resolution mass measurements and metastable peak analysis. The decomposition patterns of the compounds investigated are strongly affected by N-substitution and by methyl substituents ortho to the bridging chains (ortho effects). A unique feature connected with symmetrical macrocycles, bearing at least two ortho methyl substituents on each phenyl ring, is the presence in their spectra of diagnostically important peaks, corresponding to [M ? RNH₂]⁺˙ and [M ? 2RNH₂]⁺˙ (R = Ts, H, CH₃). These daughter ions are proposed to be associated with the formation of cage compounds (multibridged cyclophanes), generated by an intramolecular [4 + 4] cycloaddition reaction of unstable linear bis-(o-xylylene) precursors.     

Effect of isopropylidene replacement on gas transport properties of polycarbonates

The gas sorption and transport properties of a series of polycarbonates in which the isopropylidene unit of bisphenol A polycarbonate has been replaced with another molecular group are presented. Two new materials, bisphenol of norbornane polycarbonate (NBPC) and bisphenol Z polycarbonate (PCZ), are compared with several polymers which have been studied previously in this laboratory, including bisphenol A polycarbonate (PC), hexafluorobisphenol A polycarbonate (HFPC), and bisphenol of chloral polycarbonate (BCPC). The effect of molecular structure on chain mobility and chain packing is related to the gas transport properties. Dynamic mechanical thermal analysis and differential scanning calorimetry are used to judge chain mobility, while x-ray diffraction and free volume calculations give information about chain packing. Permeability measurements were made for He, H₂, O₂, N₂, CH₄, and CO₂ at 35°C over a range of pressures up to 20 atm. Sorption experiments were also done for N₂, CH₄, and CO₂ under the same conditions. The permeability coefficients of these polymers rank in the order HFPC ? NBPC>PC>BCPC ? PCZ for all of the gases. With the exception of BCPC, this order correlates well with fractional free volume. The low gas permeability of BCPC is attributed to a polarity effect. In general, bulky and relatively immobile substituents, as in HFPC and NBPC, can yield improved separation characteristics. The polar group of BCPC and the flexible cyclohexyl substituent of PCZ result in relatively low gas permeability.     

Stable,Hydroxyl Functional Polycarbonates With Glycerol Side Chains Synthesized From CO2 and Isopropylidene(glyceryl glycidyl ether)

A series of functional polycarbonates, poly((isopropylidene glyceryl glycidyl ether)‐co‐(glycidyl methyl ether) carbonate) (P((IGG‐co‐GME) C)) random copolymers with different fractions of 1,2‐isopropylidene glyceryl glycidyl ether (IGG) units, is synthesized. After acidic hydrolysis of the acetal protecting groups, a new type of functional polycarbonate prepared directly from CO₂ and glycerol is obtained, namely poly((glyceryl glycerol)‐co‐(glycidyl methyl ether) carbonate) (P((GG‐co‐GME) C)). All hydroxyl functional samples exhibit monomodal molecular weight distributions with PDIs between 2.5 and 3.3 and M _n between 12 000 and 25 000 g mol⁻¹. Thermal properties reflect the amorphous structure of the polymers. The materials are stable in bulk and solution.     

Catalytic Dibenzocyclooctene Synthesis via Cobalt(III)–Carbene Radical and ortho‐Quinodimethane Intermediates

The metalloradical activation of ortho‐benzallylaryl N‐tosyl hydrazones with [Co(TPP)] (TPP=tetraphenylporphyrin) as the catalyst enabled the controlled exploitation of the single‐electron reactivity of the redox non‐innocent carbene intermediate. This method offers a novel route to prepare eight‐membered rings, using base metal catalysis to construct a series of unique dibenzocyclooctenes through selective C_carbene?C_aryl cyclization. The desired eight‐membered‐ring products were obtained in good to excellent yields. A large variety of aromatic substituents are tolerated. The proposed reaction mechanism involves intramolecular hydrogen atom transfer (HAT) to Co^III–carbene radical intermediates followed by dissociation of an ortho‐quinodimethane that undergoes 8π cyclization. The mechanism is supported by DFT calculations, and the presence of radical‐type intermediates was confirmed by trapping experiments.     

trans‐Bis­(benzyl­amine)­di­chloro­palladium(II) bis(di­methyl sulfoxide) solvate

The title compound, [PdCl₂(C₇H₉N)₂]·2C₂H₆OS, crystallizes with two mol­ecules of di­methyl ­sulfoxide (DMSO) in monoclinic space group P2₁/n. The Pd complex is centrosymmetric and thus the phenyl rings of the benzyl­amine ligands are exo with respect to one another. The crystal packing reveals NH?O and CH?Cl hydrogen bonds between the organometallic mol­ecule and the DMSO mol­ecules, resulting in infinite chains. The distances of the ortho‐H atoms on the phenyl ring to the metal center are in the range 4.71–5.34 Å, precluding any significant intramolecular Pd?H interactions.     

The ortho effect in the mass spectra of ortho/para isomers of bisphenol a derivatives and related compounds

New examples of the ortho effect in bisphenol A derivatives including interaction of the hydrogen of the ortho-hydroxy group with the neighbouring aromatic ring have been observed. The characteristic ions [M ? PhOH]^+middot; (m/z = 134) and [M ? CH₃ ? PhOH]⁺ (m/z = 119) were shown to form through the hydrogen transfer from hydroxy and isopropyl groups, respectively. The spectra of cyclic derivatives having ortho-hydroxy functions show [M ? 43]⁺, [M ? C₈H₉O]⁺, m/z = 147, m/z = 135 and [M ? C₉H₁₀O]⁺ ions. The proposed mechanims of the corresponding transformations were supported by mass spectra of deuterated analogues, methyl and trimethyl silyl ethers.     

17O NMR studies of ortho‐substituent effects in substituted phenyl tosylates

¹⁷O NMR spectra for 35 ortho‐, para‐, and meta‐substituted phenyl tosylates (phenyl 4‐methylbenzenesulfonates), 4‐CH₃‐C₆H₄SO₂OC₆H₄‐X, at natural abundance in acetonitrile at 50 °C were recorded. The ¹⁷O NMR chemical shifts, δ(¹⁷O), of the sulfonyl (SO₂) and the single‐bonded phenoxy (OPh) oxygens for para and meta derivatives correlated well with dual substituent parameter treatment using the Taft inductive, σ_I, and resonance, σº_R, constants. The influence of ortho substituents on the sulfonyl oxygen and the single‐bonded phenoxy oxygen chemical shifts, δ(¹⁷O), was found to be nicely described by the Charton equation: δ(¹⁷O)_ortho = δ(¹⁷O)_H + ρ_Iσ_I + ρ_Rσ°_R + δE_s^B when the data treatment was performed separately for electron‐donating +R substituents and electron‐attracting ?R substituents. Electron‐attracting meta and para substituents in the phenyl moiety caused deshielding while the electron‐donating meta, para and ortho +R substituents produce shielding effects on the sulfonyl (SO₂) and single‐bonded phenoxy (OPh) oxygens. The influence of ortho inductive and resonance effects in the case of +R substituents was found to be approximately twice higher than the corresponding influence from the para position. Due to the steric effect of ortho substituents a decrease in shielding of the oxygens at the sulfonyl group (δE_s^B > 0, E_s^B < 0) was detected. Copyright © 2012 John Wiley & Sons, Ltd.     

The mutual influence of the imine substituents of terephthal-bis-imines concerning their reactivity towards Fe2(CO)9

The reaction of terephthal-bis-imines with Fe₂(CO)₉ proceeds via a C---H activation reaction in the ortho position with respect to one of the imine functions. The corresponding hydrogen atom is shifted towards the former imine carbon atom producing a methylene group instead. The dinuclear iron complexes formed by this reaction sequence and showing no coordination of the second imine group were isolated from reactions of bis-imines with both phenyl and cyclohexyl substituents at the imine nitrogen atoms. In addition, we observed three different reaction pathways of the second imine substituent of the starting material which is obviously thus influenced by the fact that the first one is coordinating an Fe₂(CO)₆ moiety. If the organic substituent at the imine nitrogen atoms is a phenyl group the formation of a trinuclear complex is achieved in which an additional Fe(CO)₃ group is coordinating the CN double bond and one of the carbon---carbon bonds of the central phenyl ring in an η⁴-fashion. The same reaction leads to the isolation of a tetranuclear iron---carbonyl compound in which both imine substituents were transformed via the pathway described above, each building up dinuclear subunits. In contrast to this the reaction of a bis-imine with cyclohexyl groups at the imine nitrogen and thus an enhanced nucleophilicity leads to the formation of a tetranuclear complex in which only one imine group reacts under C---H activation with subsequent hydrogen migration towards the former imine carbon atom. The second imine substituent also shows a C---H activation reaction in the ortho position with respect to the imine group but the corresponding hydrogen atom is transferred to one of the aromatic carbon atom of the central phenyl ring of the ligand. The C=N double bond remains unreacted and only coordinates the second Fe₂(CO)₆ moiety via the nitrogen lone pair.     

Reaction of N‐(phenyl and methyl)‐C‐arylnitrones with DMAD in ionic liquid: Efficient synthesis of Δ4‐isoxazolines

Facile synthesis of N‐(methyl and phenyl)‐Δ⁴‐isoxazolines via the reaction of (Z)‐N‐(methyl and phenyl)‐C‐arylnitrones with dimethyl acethylenedicarboxylate, DMAD, in ionic liquid is described. (Z)‐N‐methyl‐C‐arylnitrones afforded the high yield of N‐methyl‐Δ⁴‐isoxazolines 4a , 4b , 4c , 4d , 4e in ionic liquid, [bmim]BF₄, at room temperature. However, the reaction of (Z)‐N‐phenyl‐C‐arylnitrones with DMAD afforded the mixtures of cis and trans isomers of related N‐phenyl‐Δ⁴‐isoxazolines ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h , 6i , 6j ) under these conditions. J. Heterocyclic Chem., (2012).     

Control of Conformation and Chirality of Nonplanar π‐Conjugated Diporphyrins Using Substituents and Axial Ligands

Nonplanar conformations of pyrazine‐fused Zn^II diporphyrins could be controlled by the choice of the meso‐aryl substituents and an axial ligand on the central metals. Zn^II diporphyrins bearing sterically demanding meso‐aryl groups with ortho‐substituents led to a twisted chiral D₂ conformation, while an achiral C_2h form was preferred in the case of aryl groups without ortho‐substituents. Helical chirality induction on Zn^II diporphyrins in the twisted conformation was achieved by controlling their handedness of the molecular twist through coordination of optically active 1‐phenethylamine.     

1‐[4‐(Methyl­sulfonyl)­phenyl]‐5‐phenyl‐1H‐pyrazole derivatives

Three related compounds containing a pyrazole moiety with vicinal phenyl rings featuring a methyl­sulfonyl substituent are described, namely 3‐methyl‐1‐[4‐(methyl­sulfonyl)­phenyl]‐5‐phenyl‐1H‐pyrazole, C₁₇H₁₆N₂O₂S, ethyl 1‐[4‐(methyl­sul­fonyl)­phenyl]‐5‐phenyl‐1H‐pyrazole‐3‐carboxyl­ate, C₁₉H₁₈N₂O₄S, and 1‐[4‐(methyl­sulfonyl)­phenyl]‐3‐[3‐(morpholino)­phenoxy­methyl]‐5‐phenyl‐1H‐pyrazole, C₂₇H₂₇N₃O₄S. The design of these compounds was based on celecoxib, a selective cyclo­oxy­genase‐2 (COX‐2) inhibitor, in order to study the influence of various substituents on COX‐2 and 5‐lipoxy­genase (5‐LOX) inhibition.     

How do the substituents affect and regulate the relative retention times of polychlorinated biphenyls during gas chromatography?

The effects and regulatory actions of the polychlorinated biphenyls (PCBs) substituent characteristics on their relative retention times (RRTs) during gas chromatography were analyzed based on known experimental RRTs of 209 PCB congeners and biphenyl; the substituent characteristics used for this analysis included the total amount of substituents, the similarity between two phenyl rings in a single PCB congener, the substituents distribution in single phenyl ring, the main/second‐order interactions effects at each position, and the combined effect of two phenyl rings. At last, the universality of regulation was validated on other experimental conditions. Among them, the full factorial experimental design included 10 factors correlated with each substituent position and two levels (0, 1) were initially applied to the domains of the substituent characteristics. The obtained results have revealed that increasing the total amount of substituents can increase the RRTs of PCBs linearly, but similarities between the two rings cannot control the RRTs effectively. Meanwhile, the more compact the substituent distributions on a single phenyl ring are, the bigger the RRTs of PCBs are. Based on a full factorial experimental design, the overall important trend for each position is as follows: para > meta > ortho and the main regulatory substituents for the second‐order interaction effects are distributed in the same phenyl ring in the following sequence: N_o > N_m > N_p. The congener with two perpendicular phenyl rings exhibits a milder combined effect on RRTs and smaller RRT relatively. The regulation has a good universality among different experimental conditions, revealing the dominant effect of substituent characteristics on RRTs of PCBs. Copyright © 2015 John Wiley & Sons, Ltd.     

Conformational Behaviour of Substituted 2-Methoxy-2-Oxo-1,2-Oxaphospholan-3-Ols

Abstract

Conformational behaviour of about 30 2-methoxy-2-oxo-1,2- oxaphospho l an-3-0 1 s containing various substituents was examined by ¹H and ¹³C NMR. Vicinal coupling constants J(HCCH), J(HCCP), J(HCOP), J(CCOP) and J(CCCP) were employed in this study. Conformation of the 1,2-oxaphospholane ring is governed almost exclusively by substituents at C-3, C-4 and C-5, as we l l as by their orientation. The configuration of the P atom has little or no influence on conformation of the ring in diastsreomeric pairs. Strong preference of phenyl, methyl and substituted methyl groups to occupy the equatorial or pseudoequatoria l positions was observed for all but one compounds studied. In the cis-fused bicyclic syst ems conformat ionally rigid 6-membered rings forced the 1,2-oxaphospholane rings to adopt an enve l ope-l ike (E₄) conformation. No influence of the p=o……HO-C-3 hydrogen bond on conformation of the 1,2-oxaphospholane ring was found. Preferred conformations for (2R, 3R, 4R)-3-(hydroxymethyI)-2-methoxy-2-oxo-1,2-oxaphospho lane-3,4-diol and its triacetate are shown below.     

Methylene Bridging Effect on the Structures,Lewis Acidities and Optical Properties of Semi-planar Triarylboranes

Three synthetic methods towards semi-planar triarylboranes with two aryl rings connected by a methylene bridge have been developed. The fine-tuning of their stereoelectronic properties and Lewis acidities was achieved by introducing fluorine, methyl, methoxy, n-butyl and phenyl groups either at their exocyclic or bridged aryl rings. X-ray diffraction analysis and quantum-chemical calculations provided quantitative information on the structural distortion experienced by the near planar hydro-boraanthracene skeleton during the association with Lewis bases such as NH₃ and F⁻. Though the methylene bridge between the ortho-positions of two aryl rings of triarylboranes decreased the Gibbs free energies of complexation with small Lewis bases by less than 5 kJ mol⁻¹ relative to the classical Lewis acid BAr₃, the steric shielding of the CH₂ bridge is sufficient to avoid the formation of Lewis adducts with larger Lewis bases such as triarylphosphines. A newly synthesized spirocyclic amino-borane with a long intramolecular B−N bond that could be dissociated under thermal process, UV-irradiation, or acidic conditions might be a potential candidate in Lewis pairs catalysis.     

Losartan potassium,a non‐peptide agent for the treatment of arterial hypertension

In the title compound, potassium 2‐butyl‐4‐chloro‐1‐{[2′‐(5‐tetrazolido)­bi­phenyl‐4‐yl]­methyl}‐1H‐imidazol‐5‐yl­methanol, K⁺·C₂₂H₂₂ClN₆O^?, the imidazole and tetrazole rings are at angles of 85.0 (2) and 51.8 (1)°, respectively, to the phenyl rings to which they are attached, while the dihedral angle between the latter two rings is 46.7 (1)°. The coordination sphere of the metal cation consists of six tetrazoyl N atoms, the methanol O atom and the π cloud of one of the phenyl rings. These interactions determine the formation of columns of molecular anions that lie parallel to the b axis, while hydrogen bonding contributes to intercolumnar cohesion. Far from the centre of the columns, the hydro­carbon chain is immersed in a hydro­phobic environment.     

THE EFFECTS OF PERIPHERAL SUBSTITUENTS ON THE KINETICS OF ZINC ION INCORPORATION AND ACID CATALYZED REMOVAL FROM WATER SOLUBLE SULFONATED PORPHYRINS

Abstract

The kinetics of Zn²⁺ and Zn(OH)⁺ incorporation into and the kinetics of the acid catalyzed removal of Zn(II) from twelve water-soluble, sulfonated derivatives of tetraphenylporphyrin with alkyl or halogen groups in the para, ortho or di-ortho positions were investigated. While the incorporation reactions showed little dependence on porphyrin basicity, the Zn-P (P = porphyrin derivative) acid solvolysis reactions were faster the higher the basicity of the free base (H₂-P) compound. Equilibrium constants for the formation of cadmium porphyrins decreased with an increase in porphyrin basicity. The predeformed tetrakis(4-sulfonatophenyl)-β-octabromo-porphyrin reacted with Zn²⁺ about 10³ times faster than porphyrins of similar basicity. These results indicate how substituents on the phenyl and beta-pyrrole rings influence the solution chemistry of water soluble porphyrins.