David R. McMillin's research while affiliated with Purdue University and other places

Publications (225)

Article
Atoms may repel or attract each other, but bound systems get virtually all of the attention in the classroom. To address the imbalance, instructors can explore the basis of repulsion in a few simple systems and highlight the important role played by the Pauli principle. A good example is the first triplet excited state of H2wherein both electrons h...
Article
PtI2(5,5'-bis(HCF2CH2OCH2)-2,2'-bpy)], 55-2FH-PtI 2 , is the first example of a substituted fluorinated diiodoplatinum diimine complex that exhibits polymorphism. The complex, upon recrystallization, forms two different polymorphs, denoted as α and β forms. The luminescence of the α and β forms are the same in glassy solution at 77 K; however, in t...
Article
The oxidation pathways and products of a discrete, sulfide endcapped donor-acceptor-donor (D/A/D) molecule, namely propylenedioxythiophene-benzothiadiazole-propylenedioxythiophene, are investigated. The electrochemical and chemical oxidations proceed by two distinct pathways. Specifically, electrochemical oxidation undergoes a sequential two-step,...
Article
The Pauli exclusion principle is a key postulate of the quantum theory and informs much of what we know about matter. In terms of electronic structure, the lone, deceptively simple mathematical requirement is that the total wave function be antisymmetric with respect to the exchange of any two electrons. However, visualizing the effect on the elect...
Article
Inserting a heteroatom between two pyridine rings of the trpy framework leads to an increase in the overall intraligand bite angle of 8−10° in crystal structures of [Pt(btp)Cl]⁺ and [Pt(bmap)C2Ph]⁺. However, angle strain within the six-membered chelate ring results in a boat-like local conformation and pseudotetrahedral coordination at the metal. O...
Article
Students collect magnetic susceptibility data to verify that Hund’s rule correctly predicts electronic configurations. Systems examined include three commercially available lanthanide(III)-containing complexes of the form M(acac)3(H2O)2 (where M = La(III), Nd(III), and Gd(III), and acac denotes the [CH3C(O)CHC(O)CH3]⁻ anion, i.e., deprotonated acet...
Article
Electronic spectra often exhibit vibronic structure when vibrational and electronic transitions occur in concert. Theory reveals (1) that orbital symmetry considerations determine specific roles played by the nuclear degrees of freedom and (2) that the vibrational excitation is often highly regiospecific, that is, attributable to an identifiable su...
Article
We report here the synthesis of bis(DEDT –S,S)-μ-(naphthyl-1,8) digold(II) (1) (DEDT = diethyldithiocarbamate) with a formal Au-Au bond. Complex 1 is formed from the reaction of Au(DEDT)Cl2 with 1,8-dilithioaphthalene, a unique synthesis as gold(II) complexes are traditionally synthesized by oxidative addition of digold(I) complexes. Complex 1 was...
Article
The goal of this work has been to synthesize and investigate Pd(TC3), an intercalating porphyrin that has conformable substituents capable of groove binding to B-form DNA. (TC3 denotes the doubly deprotonated form of 5,10,15,20-tetra[3-(3'-methylimidazolium-1'-yl)prop-1-yl]porphyrin.) Palladium(ii) is an apt choice for the central metal ion because...
Article
We report here a series of emissive biphenyl cyclometalated gold(III) diethyl dithiocarbamate complexes having H, CF3, OMe, and tBu substitutions on the biphenyl moiety. Synthesis of these complexes was accomplished by a single-step reaction of the appropriate dilithio-biphenyl reagent with Au(dtc)Cl2 (dtc = diethyl dithiocarbamate). All four compl...
Article
The f-f emissions of lanthanide ion complexes have predictable emission energies and many practical applications, but the emitting states are generally impervious to the surroundings. This investigation explores ligand- and metal-centered emission processes for a series of mixed-ligand complexes of composition M(X-T)(NO3)3 where the metal ion is eu...
Article
The laboratory experiment described provides insight into the energetics of hydrogen evolution at an electrode as well as the intrinsic barrier that typically impedes reaction. In the course of the exercise, students find that Sn(s) is thermodynamically capable of combining with protons to form hydrogen, but that the direct reaction occurs at a neg...
Article
This investigation explores binding interactions involving G-quadruplex DNA and two copper(II)-containing porphyrins (5,10,15,20-tetra(N-methylpyridinium-4-yl)porphyrinato)copper(II) and the sterically friendlier analogue (trans-5,15-di(N-methylpyridinium-4-yl)porphyrinato)copper(II), or Cu(T4) and Cu(tD4), respectively. The study incorporates five...
Article
All-synthetic molecular donor-acceptor complexes are designed, which are capable of counteracting the effect of photo-induced degradation of donor chromophores. Anionic gallium protoporphyrin IX (GaPP) and semiconducting carbon nanotube (CNT) are used as a model donor-acceptor complex, which is assembled using DNA oligonucleotides. The GaPP-DNA-CNT...
Article
This investigation explores DNA-binding interactions of various forms of an alkyl-substituted cationic porphyrin, H2TC3 (5,10,15,20-tetra[3-(3'-methylimidazolium-1'-yl)]porphyrin). The motivating idea is that incorporating alkyl rather than aryl substituents in the meso positions will enhance the prospects for intercalative as well as external bind...
Article
Donor–acceptor complexes of porphyrins and semiconducting single-walled carbon nanotubes (SWCNTs) are noncovalently assembled using oligonucleotide DNA, and their photophysical interactions are studied for light-harvesting. Five cationic 5,10,15,20-tetrakis(N-methylpyridynium-4-yl)porphyrins with a free-base (H2T4) or metal ions at the core (MT4, M...
Article
Absorbance, induced circular dichroism, and emission studies establish that the tetrasubstituted cationic porphyrin Cu(T4) preferentially binds externally to single-stranded (ss) DNA sequences, except in a purine-rich system like 5'-(dA)10-3' where a degree of internalization occurs. On the other hand, the sterically friendly, disubstituted Cu(tD4)...
Article
Studies reveal that it is possible to design a palladium(II)-containing porphyrin to bind exclusively by intercalation into double-stranded DNA while simultaneously enhancing the ability to sensitize the formation of singlet oxygen. The comparisons revolve around the cations [5,10,15,20-tetra(N-methylpyridinium-4-yl)porphyrin]palladium(II), or Pd(T...
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Full-text available
The yellow () and orange () crystalline polymorphs of [PtBr2(5,5'-bis(CF3CH2OCH2)-2,2'-bipyridine)] exhibit surprisingly short nearest neighbour PtPt separations of 3.526 Å and 3.590 Å, respectively, at 295 K. Both distances are much shorter than those found in structures of the unsubstituted [PtBr2(2,2'-bipyridine)] analogue. Consistent with a lin...
Article
Ruthenium(II) in combination with monodentate, bidentate, and tridentate ligands has proven to be a useful design for a variety of applications, but the majority of systems are virtually nonluminescent in solution. The goal of this work has been to design luminescent forms with practicable emission quantum yields, and the focus has been on [Ru(X-T)...
Article
The preparation of nanoparticulate RuO2 supported on mesoporous silica SBA-15 was optimized to achieve a uniform dispersion and confinement of RuO2. The supported RuO2 (NP2) has been used as the catalyst for photoinduced water oxidation with Ru(bpy)32+ as the photosensitizer and S2O82– as the sacrificial oxidant. Both NP2 and the previously prepare...
Article
Introducing electron-donating groups extends the excited-state lifetimes of platinum(II)-terpyridine complexes in fluid solution. Such systems are of interest for a variety of applications, viz., as DNA-binding agents or as components in luminescence-based devices, especially sensors. The complexes investigated here are of the form [Pt(4'-X-T)Y](+)...
Article
Light harvesting nanostructure hybrids have been designed and demonstrated using single-wall carbon nanotubes (SWCNTs) and porphyrin chromophores. DNA oligonucleotides are used to conjugate SWCNTs with light-absorbing chromophores for transparent films which generate photocurrents. High-purity semiconducting SWCNTs demonstrate significant enhanceme...
Article
Many platinum(II) polypyridine complexes are good luminophores, an enigmatic exception being Pt(trpy)Ph(+), where trpy denotes 2,2':6',2″-terpyridine. A new analysis suggests the complex is nonemissive due to (3)SBLCT (sigma-bond-to-ligand charge transfer) character in the lowest energy excited state. Bases for two distinct strategies for inducing...
Article
A cationic, copper(II)-containing ligand, derived from bulky 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin, Cu(T4), and two sterically friendlier forms, [trans-5,15-di(N-methylpyridinium-4-yl)porphyrinato]copper(II), Cu(tD4), and [cis-5,10-di(N-methylpyridinium-4-yl)porphyrinato]copper(II), Cu(cD4), bind to DNA and RNA hosts. Six hairpin-fo...
Article
The carbometalated complex Pt(dppzφ*)Cl, where dppzφ* denotes the 6-(4-tert-butylphenyl)-dipyrido[3,2-a:2',3'-c]phenazine ligand, exhibits emission in a dichloromethane solution at room temperature with a concentration-dependent excited-state lifetime. Extrapolation to zero Pt(dppzφ*)Cl concentration yields a limiting lifetime of 11.0 μs in the abs...
Article
Full-text available
This report describes photoluminescence studies of copper-containing [2]pseudorotaxanes that mimic elements of functioning molecular machines. Excitation with visible light induces a formal oxidation of the metal center and simulates an actuation process. In all four [2] pseudorotaxanes studied, the ring ligand is the same, but the thread ligand is...
Article
There are many possible applications for luminescent platinum terpyridine (trpy) complexes, but the emission quantum yield and lifetime vary greatly depending upon the design. One reason is that potentially emissive metal-to-ligand charge-transfer (MLCT) states occur at relatively high energies because a planar coordination geometry is not the best...
Article
Full-text available
The emission spectra of the solids [n-Bu(4)N](2)Tc(2)X(8) (X = Cl, Br) have been investigated at room temperature and 77 K. In each case, the emission originates in the (1)δ-δ* excited state, as with the rhenium homologues, but has a shorter lifetime.
Article
Delocalization of the charge-transfer excitation in the series [Ru(NNN)(bpy)CN](+) [bpy = 2,2'-bipyridine; 1, NNN = 2,2':6',2''-terpyridine; 2, NNN = 2-(2'-pyridyl)-1,10-phenanthroline or php; 3, NNN = 6'-(2''-pyridyl)dipyrido[3,2-a:2',3'-c]phenazine or dppzp] proves to be an effective way of tuning photophysical properties. Red-emitting 3 function...
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Full-text available
The synthesis and characterisation of the 4-(o-tolyl)-6-(3´´-isoquinolyl)-2,2´-bipyridyl [4-(otolyl) isqbipy] ligand is described. A single-crystal X-ray structure determination shows that it adopts a trans-trans conformation about the interannular bonds linking the central pyridine ring to the outer pyridine ring and the isoquinolyl moiety. The o-...
Article
The binding motifs of copper(II) porphyrins with G quadruplex DNA structures vary markedly depending on the steric demands of the ligand and the host structure.
Article
This paper focuses on DNA-binding interactions exhibited by Pt(dma-T)CN(+), where dma-T denotes 4'-dimethylamino-2,2':6',2''-terpyridine, and includes complementary studies of the corresponding pyrr-T complex, where pyrr-T denotes 4'-(N-pyrrolidinyl)-2,2':6',2''-terpyridine. The chromophores are useful for understanding the interesting and rather i...
Article
Neutral orthometalated platinum(II) complexes of the deprotonated 6-phenyl-2,2'-bipyridine ligand (bearing a trialkoxygallate, tolyl, ethynyltrialkoxygallate, or ethynyltolyl substituent) and a sigma-bonded Cl, ethynyltolyl, or ethynyltrialkoxygallate coligand have been prepared by a stepwise procedure based on copper-promoted cross-coupling reacti...
Article
For most molecules molecular orbital theory predicts a ground-state electronic configuration that is useful for rationalizing relative bond lengths, magnetic properties, and so forth. However, when electron correlation is a dominant consideration, the ground-state configuration may provide a poor representation of the system. In such cases, invokin...
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Full-text available
Vapour diffusion of diethyl ether into a concentrated solution of [Pt{4′-(o-ClC6H4)trpy}(CN)]SbF6 (trpy = 2,2′:6′,2″-terpyridine) in acetonitrile induces the concomitant formation of orange and yellow single crystals that have been shown by means of X-ray crystal structure determinations at 200 K to be different polymorphs of the compound. The [Pt{...
Article
This report describes platinum(II) complexes of 6-(2-pyridyl)-dipyrido[3,2- a:2',3'- c]phenazine (dppzp) and 6-phenyl-dipyrido[3,2- a:2',3'- c]phenazine (dppzphi). The [Pt(dppzp)Cl] (+) ( 1) system exhibits an excited-state lifetime of 5.0 micros in deoxygenated dichloromethane. Lewis bases quench the emission with rate constants on the order of 10...
Article
Positively charged N-methylpyridinium-4-yl substituents promote the binding of a porphyrin to DNA, but they also impose steric constraints. To clarify when intercalative binding is most feasible, this report describes syntheses and binding studies of two tricationic ligands: 5,10,15-tri(N-methylpyridinium-4-yl)porphyrin (H2Tri4) and 5-methyl-10,15,...
Article
Abstract— The concentration dependence of the lifetimes of the charge transfer excited states of Cu(dmp)+2 and Cu(dpp) +2 has been investigated in CH2C12 solution at 20°C. (dmp denotes 2,9-dimethyf-1,10-phenanthroline, and dpp denotes 2,9-diphenyl-l,10-phenanthroline.) In dilute solution (< 30 μM) the lifetime of Cu(dmp)+2, is 95 ± 5 ns, independen...
Article
Cationic porphyrins have an affinity for DNA and potential for applications in the fields of photodynamic therapy and cellular imaging. This report describes a new dicationic porphyrin, 5,15-dimethyl-10,20-di(N-methylpyridinium-4-yl)porphyrin, abbreviated H2tMe2D4. Although tetrasubstituted, H2tMe2D4 presents modest steric requirements and forms in...
Article
The synthesis and characterisation of an orange polymorph of [Pt(trpy)(CCPh)]SbF6 is described where trpy=2,2′:6′,2″-terpyridine. An X-ray crystal structure determination at 293K reveals that the cations are planar and stacked head-to-tail with alternating Pt⋯Pt distances of 3.604(1) and 4.412(1)Å. The perpendicular distances between successive cat...
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Full-text available
The synthesis and characterisation of the 4-(o-R-C6H 4)pzbipy [R = H, CH3 or CF3; pzbipy = 6-(2″-pyrazinyl)-2,2′-bipyridyl] ligands are described. Reaction of the 4-(o-MeC6H4)pzbipy ligand with [Pt(PhCN) 2Cl2] in the presence of AgSbF6 affords [Pt(4-(o-MeC6H4)pzbipy}Cl]SbF6 as a marooncoloured microcrystalline solid. The [Pt{4-(o-MeC6H 4)pzbipy)Cl]...
Article
The synthesis and characterization of [Pt{4′-(R)trpy}(CN)]X (R = Ph, X = BF4 or SbF6; R = o-CH3C6H4, X = SbF6; R = o-ClC6H4, X = SbF6; or R = o-CF3C6H4, X = SbF6) are described where trpy = 2,2′:6′,2″-terpyridine. Single crystals of [Pt{4′-(Ph)trpy}(CN)]BF4·CH3CN were grown by vapour diffusion of diethyl ether into an acetonitrile solution of [Pt{4...
Article
The synthesis and characterisation of [Pt{4′-(Np1)-trpy}(CCPh)]SbF6 (1) and [Pt{4′-(Np1)-trpy}{CC(CH2)2CH3}]SbF6 (2) [4′-(Np1)-trpy = 4′-(1-naphthyl)-2,2:6′,2′-terpyridine] are described. Complexes 1 and 2 exhibit unimolecular 3MLCT (MLCT = metal-to-ligand charge transfer) emission in acetonitrile and in a low concentration 77 K glass solution in b...
Article
Reactions between Re2(DMBA)4(NO3)2 (1; DMBA is dimethylbenzamidinate) and a bidentate dianion, either tungstate (WO4(2-)) or terephthalte (1,4-(O2C)2C6H4(2-)), resulted in the one-dimensional coordination polymers [Re2(DMBA)4(mu-O,O'-WO4)](infinity) (2) and [Re2(DMBA)4(mu-O,O'-1,4-(O2C)2C6H4)](infinity) (3), respectively. Both polymers display phos...
Article
As part of an effort to develop new lumaphors involving late transition metal ions, this report describes the synthesis and characterization of the first platinum(II) derivatives containing 2,2':6',2''-terpyridine (trpy) and cyanide as co-ligands. According to existing models, including cyanide in the coordination sphere should raise the energies a...
Article
The DNA-binding interactions of 5,10,15,20-tetra(N-methylpyridinium-4-yl)porphyrin, herein denoted H2T4, and related cationic porphyrins have long been of interest because of the potential for therapeutic applications and the novel binding interactions observed with DNA. A brief review of available physical studies reveals that the monomeric porphy...
Article
The ligand 2-(8'-quinolinyl)-1,10-phenanthroline (1) was prepared in 79% yield by the Friedlander condensation of 8-amino-7-quinolinecarbaldehyde and 8-acetylquinoline. The complex [Pt(1)Cl]+ was prepared and compared with the isomeric 2-(2'-quinolinyl)-1,10-phenanthroline (2) complex. An X-ray analysis indicated that the six-membered chelate ring...
Article
DNA hairpins are extremely versatile hosts for investigating DNA-binding interactions, but studies with a dicationic zinc(II) porphyrin reveal that the choice of loop sequence is critical when the aim is to understand adduct formation with very much longer, naturally occurring sequences.
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This paper describes the synthesis and characterization of a new series of sterically nondemanding, dicationic porphyrins that exhibit novel DNA-binding interactions. Cationic porphyrins continue to be the focus of a great deal of effort because of the promise they have for use in photodynamic, antiviral, and anticancer therapies. The systems explo...
Article
The synthesis and characterisation of 4′-(2-chlorophenyl)-2,2′:6′,2″-terpyridine [4′-(o-ClC6H4)trpy] and [Pt{4′-(o-ClC6H4)trpy}Cl]SbF6 are described. An X-ray crystal structure determination of the salt reveals columns of cations and anions with the cations stacked parallel and head-to-tail. At 295 K the PtPt distances alternate between 3.374(1) an...
Article
This research deals with the synthesis and characterization of a new series of platinum(II) polypyridine complexes that incorporate a relatively rigid and hydrophobic ligand. The parent complex Pt(php)Cl(+), where php denotes 2-(2'-pyridyl)-1,10-phenanthroline, resembles Pt(trpy)Cl(+), where trpy denotes 2,2':6',2''-terpyridine, but is photolumines...
Article
The pseudotetrahedral complexes [Cu(NN)(DPEphos)]BF(4), where DPEphos = bis[2-(diphenylphosphino)phenyl]ether and NN = 1,10-phenanthroline (1), 2,9-dimethyl-1,10-phenanthroline (2), 2,9-di-n-butylphenanthroline (3), or two dimethylcyanamides (4), and NiCl(2)(DPEphos) (5) have been synthesized and structurally characterized by X-ray crystallography...
Article
This report outlines progress to date in preparing Pt(trpy)Cl+ derivatives that exhibit long-lived photoluminescence in solution (trpy=2,2′;6′,2″-terpyridine). The trpy complex itself is a versatile binding agent/reporter probe for biological macromolecules but is non-emissive, except in solids or low-temperature glasses. Derivatives investigated a...
Article
Full-text available
The synthesis and characterisation of 4′-(2-methylphenyl)-2,2′:6′,2″-terpyridine [4′-(o-CH3–Ph)trpy] and 4′-(2-trifluoromethylphenyl)-2,2′:6′,2″-terpyridine [4′-(o-CF3–Ph)trpy] are described. Reaction of these ligands with [Pt(PhCN)2Cl2] in the presence of the appropriate silver salt afforded [Pt{4′-(o-CH3–Ph)trpy}Cl]A and [Pt{4′-(o-CF3–Ph)trpy}Cl]...
Article
This report describes new, readily accessible copper(I) complexes that can exhibit unusually long-lived, high quantum yield emissions in fluid solution. The complexes are of the form [Cu(NN)(POP)]+ where NN denotes 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,9-di-n-butyl-1,10-phenanthroline (dbp) and POP denotes bis[2-(d...
Article
Cationic porphyrins such as meso-tetrakis(4-(N-methylpyridiumyl))porphyrin, or H2T4, are remarkably versatile DNA binding agents of interest for potential therapeutic applications. This study focuses on the influence the DNA bases have in determining the mode of uptake and the relative binding affinity. For convenience the host is usually a DNA hai...
Article
Pt(trpy)Cl+, where trpy denotes 2,2':6',2' '-terpyridine, is a versatile binding agent but has a limited photochemistry due to a short excited-state lifetime. However, this work shows that the introduction of aryl substituents at the 4' position of the trpy ligand drastically alters the picture. For the substituents phenyl, p-methoxyphenyl, 1-napht...
Article
Quenching studies involving a range of Lewis bases establish that exciplex quenching can affect the lifetime of the emissive charge-transfer state of a platinum(II) terpyridine. The evidence comes from studies of Pt(trpy)SCN+, where trpy denotes 2,2′:6′,2″-terpyridine, and a Pt(4′-XT)Cl+ series where 4′-XT denotes a 4′-substituted trpy derivative...
Article
The potential for therapeutic applications has provided much of the impetus for investigating the DNA-binding interactions of cationic metalloporphyrins, but there are also signs of intriguing base and sequence dependences. More recent work has established that the stem regions of DNA hairpins are extremely useful as model duplexes. Mainly the focu...
Article
For a variety of reasons, relating the photophysical properties of a copper phenanthroline to a structure in solution is problematic. To elucidate some of the issues involved, in this paper we describe the crystal and molecular structures of a series of Cu(NN)2(+)-containing systems along with spectral data obtained from the solids themselves. The...
Article
Attaching an electron-rich aryl substituent at the 4' position of the trpy ligand in Pt(trpy)Cl+ endows the low-lying excited state with intraligand charge-transfer (ILCT) character, enhances the emission intensity, extends the excited-state lifetime, and inhibits exciplex quenching by Lewis bases. When pyrene is the substituent, the complex exhibi...
Article
Copper phenanthrolines are attractive as potential photosensitizers because of the ready availability of the metal, but efficient nonradiative decay including a solvent-induced quenching phenomenon ordinarily limits their utility. However, the present studies show that the addition of methyl substituents in the 3,8-positions of 1,10-phenanthroline...
Article
The possibility that ceruloplasmin (CP) functions as a copper transferase has fueled a continuing interest in studies of the copper release process. The principal goal of the current investigation has been to identify the most labile copper centers in sheep protein. In fact, subjecting the enzyme to a slow flux of cyanide at pH 5.2 under nitrogen i...
Article
Very little work has been done on exploring the transition metals as suitable cationizing agents for the analysis of polymers by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF). This paper reports on the characterization of polystyrenes and polyethylene glycols with select metallocenes as cationizing agents. It was found that...
Article
Understanding the structure and function of the three copper atoms in the dioxygen reduction site of the blue oxidases such as laccase has been a long standing challenge. In the case of a widely studied derivative, known as type 2-depleted laccase, the removal of one copper from the cluster abolishes the EPR signal of the so-called type 2 copper. H...
Article
The complexes [Pt(4′Ph-terpy)Cl]A (4′Ph-terpy = 4′-phenyl-2,2′:6′,2″-terpyridine; A = SbF6, CF3SO3, or BF4) have been prepared by reaction of [Pt(PhCN)2Cl2] with the appropriate silver salt followed by addition of the 4′-phenyl-2,2′:6′,2″-terpyridyl ligand. The hexafluoroantimonate salt is yellow but, depending on the method of crystallisation, the...
Article
Inosine-for-guanine replacement in DNA hairpin hosts reveals that the intercalative binding of Cu(T4) depends upon strong hydrogen bonding within the stem.
Article
The metal-to-ligand charge-transfer excited states of Cu(NN)(2)(+) systems tend to be good reducing agents but poor oxidants for kinetic and thermodynamic reasons. However, this report demonstrates that reductive electron-transfer quenching is an important pathway for ferrocenes that react with the photoexcited states of Cu(dipp)(2)(+) and Cu(tptap...
Article
Water-soluble, cationic metalloporphyrins that bind to DNA show promise as artificial nucleases and as sensitizers for photodynamic therapy, but fundamental questions remain about the binding motifs and sequence specificities. To address these issues, we have studied the interactions of Cu(T4) with a series of oligonucleotides that form hairpin str...
Article
In view of the interest in probing the binding interactions that occur between platinum complexes and biological macromolecules, the aim of this work has been to develop systems that exhibit enhanced excited-state lifetimes and emission yields in fluid solution. The investigation focuses on a series of complexes of the type Pt(4′-X-T)Cl+ where 4′-X...
Article
The X-ray structure of [Cu(dnpp)2]PF6, where dnpp denotes 2,9-dineopentyl-1,10-phenanthroline, reveals a flattened tetrahedral copper complex with a dihedral angle between the least-squares planes of the ligands of only 63.4(1)°. Steric interactions involving γ methyl groups of the substituents have an important role in shaping the complex, but lat...
Article
The crystal structure of [Pt(trpy)(MeCN)](SbF6)2, where trpy denotes 2,2‘:6‘,2‘‘-terpyridine, shows that the platinum complex packs as a monomer; however, the 3π−π* emission of the solid occurs at surprisingly long wavelengths at room temperature. At lower temperatures new, shorter-wavelength maxima appear. Of the known salts with the composition [...
Article
For a series of copper(II) porphyrins, we report EPR data from solid solutions as well as E0 values for the first ring oxidation, emission spectra, and luminescence lifetimes in methylene chloride. Although the EPR parameters are fairly constant, the potentials vary by almost 700 mV, and the room-temperature lifetimes range from 300 ns for Cu(TCl2P...
Article
This investigation focuses on a series of pseudotetrahedral complexes of the form Cu(NN)2+, where NN denotes a 1,10-phenanthroline ligand with alkyl substituents in the 2 and 9 positions and the counterion is PF6-. In these copper(I) systems, steric effects are of considerable interest because the electronic configuration predisposes the reactive c...