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1.
J Manag Care Spec Pharm ; 29(4): 409-419, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36989453

ABSTRACT

BACKGROUND: Alopecia areata (AA) is an autoimmune disease characterized by nonscarring hair loss. AA frequently co-occurs with other inflammatory autoimmune conditions, presenting a significant clinical burden. OBJECTIVE: To compare the burden of illness, direct and indirect costs in adult patients with AA vs atopic dermatitis (AD). METHODS: This retrospective cohort study used US administrative claims data from the Merative MarketScan Commercial Claims and Encounters Database to compare commercially insured adults with AA to those with AD. Patients with an AA diagnosis between January 2017 and September 2019 were propensity score matched to patients with AD. Comorbidity burden, medication use, health care resource utilization, health care costs, and indirect costs during a 12-month follow-up period were compared between cohorts. RESULTS: Overall, 25,446 adult patients with AA were selected for the matched analysis with the AD cohort. Patients with AA generally had lower comorbidity burden than patients with AD; mean Deyo-Charlson Comorbidity Index scores were 0.36 (SD = 0.99) and 0.39 (SD = 0.92), for AA and AD, respectively (P = 0.007). Patients with AA had significantly lower proportions of allergic rhinitis, asthma, pruritus, skin infections, and urticaria, but higher proportions of thyroid disease, when compared with patients with AD (all P < 0.001). A smaller proportion of patients with AA had prescriptions for topical (45.3% vs 64.8%; P < 0.001) and oral (20.3% vs 29.6%; P < 0.001) corticosteroids and antianxiety and/or antidepressants (24.7% vs 29.7%; P < 0.001), but a significantly larger proportion for intralesional corticosteroids (triamcinolone) (49.6% vs 21.7%; P < 0.001), compared with patients with AD. Despite a lower comorbidity burden and generally less medication usage in patients with AA, total all-cause health care costs did not significantly differ between the AA and AD cohorts ($10,705 vs $10,816; P = 0.712), and outpatient costs were higher in patients with AA ($6,297 vs $5,859; P = 0.014). Female patients with AA had significantly greater costs for both outpatient and outpatient pharmacy when compared with female patients with AD. Patients with AA were more likely to have a claim for long-term disability (0.6% vs 0.3%; P = 0.001) and higher long-term disability-associated indirect costs ($73 [SD = $1,442] vs $25 [SD = $774]; P = 0.004) compared with patients with AD. CONCLUSIONS: We found similar total health care costs in patients with AA and AD, despite a lower proportion of comorbidities and prescription use in patients with AA. Outpatient costs were also significantly higher overall in patients with AA. Although often dismissed as a cosmetic condition, AA, an autoimmune disease, has a similar level of medical expenditure as AD. DISCLOSURES: This study was funded by Eli Lilly and Company. Mr Fenske and Drs Ding, Morrow, and Smith are employed by Eli Lilly and Company. Drs Manjelievskaia, Moynihan, and Silver are employed by Merative. Drs Manjelievskaia, Moynihan, and Silver were employed by IBM Watson Health at the time of study completion. IBM Watson Health received funding from Eli Lilly and Company to conduct this study.


Subject(s)
Alopecia Areata , Dermatitis, Atopic , Adult , Humans , Female , United States/epidemiology , Dermatitis, Atopic/drug therapy , Dermatitis, Atopic/epidemiology , Retrospective Studies , Alopecia Areata/drug therapy , Alopecia Areata/epidemiology , Silver/therapeutic use , Health Care Costs , Cost of Illness , Adrenal Cortex Hormones/therapeutic use
2.
Adv Ther ; 38(9): 4646-4658, 2021 09.
Article in English | MEDLINE | ID: mdl-34292518

ABSTRACT

INTRODUCTION: Alopecia areata (AA) is an autoimmune disorder causing sudden, non-scarring hair loss. There are currently no drugs approved for AA treatment. This study assessed prevalence of comorbidities, treatments, and healthcare costs and resource utilization among patients with AA in the USA. METHODS: Patients diagnosed with AA between January 2011 and December 2018 were identified in IBM MarketScan® Research Databases. Eligible patients had no other hair loss-related disorders and were continuously enrolled with medical and pharmacy benefits at least 12 months before and after AA diagnosis. Descriptive statistics were used to summarize comorbid conditions, treatments related to AA or other autoimmune/inflammatory conditions, and all-cause and AA-specific healthcare costs and resource utilization identified from claims data. RESULTS: A total of 68,121 patients with AA were identified. Mean (SD) age was 40.3 (17.8) years and 61.0% were female. The most common comorbidities included hyperlipidemia (22.4%), hypertension (21.8%), thyroid disorders (13.1%), contact dermatitis or eczema (10.8%), depression (9.5%), and anxiety (8.4%). Comorbid autoimmune diseases included atopic dermatitis (2.8%), psoriasis (2.1%), chronic urticaria (1.5%), and rheumatoid arthritis (1.1%). During the 12-month follow-up period, 37,995 patients (55.8%) were prescribed treatment for their AA or other comorbid autoimmune/inflammatory disease; 44.9% of treated patients were prescribed therapy within 7 days of AA diagnosis. Of patients receiving treatment, 80.3% received topical steroids and 30.0% received oral steroids. Mean (SD) total healthcare costs were $11,241.21 ($43,839.69) for all-causes and $419.12 ($1534.99) for AA. AA-related expenses were driven by outpatient and prescription costs. CONCLUSION: Patients with AA have a high comorbidity burden and lack of treatment. Current AA treatments, including systemic therapies other than oral steroids, were not frequently utilized in this study population. Healthcare costs incurred by patients with AA went beyond AA-related expenses. Longitudinal data are needed to better understand treatment trajectories and the disease burden in patients with AA.


Subject(s)
Alopecia Areata , Insurance , Adult , Alopecia Areata/drug therapy , Alopecia Areata/epidemiology , Comorbidity , Female , Health Care Costs , Humans , Patient Acceptance of Health Care , Retrospective Studies
3.
Clin Lung Cancer ; 18(6): 607-614, 2017 11.
Article in English | MEDLINE | ID: mdl-28571688

ABSTRACT

Brain metastases (BRM) occur frequently in non-small-cell lung cancer (NSCLC) and present a substantial unmet medical need. Previous literature on global BRM prevalence, treatment patterns, costs, and outcomes typically has described a subset of these factors. The primary objective of this systematic literature review was to summarize BRM-related epidemiology, treatment patterns, costs, and survival of patients with NSCLC in the United States, European Union, and Japan. The study was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards. Literature searches were conducted in PubMed, Ovid MedLine, and Embase to identify studies published between 2003 and 2014. Peer-reviewed, English language, and human observational studies of patients with NSCLC and BRM were identified. Demographic characteristics, treatment patterns, histology subtype, costs, and survival data were extracted into Microsoft Excel and descriptively analyzed using SAS version 9.2 (SAS Institute, Inc). Of 8257 studies, 243 were eligible. Data from 46,422 patients with NSCLC and 27,907 patients with BRM were summarized. Radiation therapy was used by 70.7% (n = 19,736) of the total BRM population, followed by systemic therapy (8.9%, n = 2497), and surgery (6.1%, n = 1690). Reported median survival was 9.78 months ranging from 2.5 to 38 months. Radiation therapy had the best outcome at 10.0 months with 41.6% (n = 101) of the studies reporting the use of stereotactic radiosurgery. Highly variable median survival and treatment patterns were reported between countries. Costs and histology subtype data were not reported for most countries, highlighting the need for additional research to describe the economic burden of BRM and improve the diagnosis, prognosis, and prescription of effective therapies.


Subject(s)
Brain Neoplasms/therapy , Carcinoma, Non-Small-Cell Lung/pathology , Lung Neoplasms/pathology , Brain Neoplasms/secondary , European Union , Humans , Japan , Prognosis , Radiosurgery/methods , Treatment Outcome , United States
4.
Inorg Chem ; 51(9): 5481-6, 2012 May 07.
Article in English | MEDLINE | ID: mdl-22515471

ABSTRACT

Using combinations of p-tert-butylthiacalix[4]arene (TCA) and [M(DMSO)(6)(BF(4))(2)] salts (M = Co(II) or Ni(II)), two almost isostructural core-shell-type thermally stable giant nanoclusters, composed of 32 metal centers, 6 deprotonated calix units binding the metal centers by both their O and S atoms, 24 µ-oxo or µ-hydroxo bridging groups, and 6 MeOH molecules, have been prepared under mild and reproducible conditions. For both giant clusters, the oxidation state II [M(II)(32)O(16)(OH)(8)(CH(3)OH)(6)TCA(6) (M = Co or Ni)] for the metal center was demonstrated by X-ray photoelectron and electronic absorption spectroscopies.

5.
Philos Trans A Math Phys Eng Sci ; 368(1915): 1207-10, 2010 Mar 28.
Article in English | MEDLINE | ID: mdl-20156822
6.
Langmuir ; 24(16): 9011-6, 2008 Aug 19.
Article in English | MEDLINE | ID: mdl-18646780

ABSTRACT

Catalytic properties of Pt nanoparticles can significantly depend on the crystallite shape, which renders shape control an important aim in the chemical synthesis. Starting from a colloidal synthesis of quasispherical Pt nanocrystals capped with dodecylamine ligands, systematic variations of different synthesis parameters were performed in the present work in order to obtain Pt nanowires. Mechanistic investigations revealed that nanowires can form by aggregation of quasispherical particles. The process of wire formation was found to be influenced by parameters such as the concentration of the stabilizing ligands on the particle surface. Furthermore, the thermal stability of the obtained nanoparticles was examined. The nanowires were found to be stable up to approximately 140-160 degrees C. In this temperature range a structural transition to a more spherical crystallite shape occurred, which can be understood by thermodynamic considerations.

7.
Expert Opin Biol Ther ; 1(6): 923-47, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11728226

ABSTRACT

Liposomes are the leading drug delivery systems for the systemic (iv.) administration of drugs. There are now liposomal formulations of conventional drugs that have received clinical approval and many others in clinical trials that bring benefits of reduced toxicity and enhanced efficacy for the treatment of cancer and other life-threatening diseases. The mechanisms giving rise to the therapeutic advantages of liposomes, such as the ability of long-circulating liposomes to preferentially accumulate at disease sites including tumours, sites of infection and sites of inflammation are increasingly well understood. Further, liposome-based formulations of genetic drugs such as antisense oligonucleotides and plasmids for gene therapy that have clear potential for systemic utility are increasingly available. This paper reviews the liposomal drug delivery field, summarises the success of liposomes for the delivery of small molecules and indicates how this success is being built on to design effective carriers for genetic drugs.


Subject(s)
Drug Delivery Systems , Liposomes , Adjuvants, Immunologic , Animals , Humans , Transfection , Vaccines
8.
Inorg Chem ; 40(19): 4816-7, 2001 Sep 10.
Article in English | MEDLINE | ID: mdl-11531424
9.
J Am Chem Soc ; 123(10): 2354-64, 2001 Mar 14.
Article in English | MEDLINE | ID: mdl-11456885

ABSTRACT

The optical properties and electronic structure of a homologous series of CdSe cluster molecules covering a size range between 0.7 and 2 nm are investigated. CdSe cluster molecules with 4, 8 10, 17, and 32 Cd atoms, capped by selenophenol ligands, were crystallized from solution and their structures determined by single-crystal X-ray diffraction. The cluster molecules are composed of a combination of adamanthane and barylene-like cages, the building blocks of the zinc blende and the wurtzite structures of the bulk CdSe. The onset of the room temperature absorption and low-temperature photoluminescence excitation spectra exhibit a systematic blue shift with reduced cluster size manifesting the quantum confinement effect down to the molecular limit of the bulk semiconductor. Blue-green emission, shifted substantially to lower energy from the absorption onset, is observed only at low temperature and its position is nearly independent of cluster size. The wavelength dependence of both photoluminescence and photoluminescence excitation was measured. The emission is assigned to forbidden transitions involving the cluster-molecule surface-capping ligands. This assignment is supported by the emission decay which exhibits distributed kinetics with microsecond time scale. The temperature dependence of the emission intensity is quantitatively explained by multiphonon-induced nonradiative relaxation mediated by low-frequency vibrations of the selenophenol capping ligands. Upon irradiation, the emission of all cluster molecules is quenched. Warming up and recooling leads to recovery of the emission (partial or complete) for all but the cluster molecule with 10 Cd atoms. This temporary darkening is assigned to the photoinduced charging of the cluster-molecule surface ligands, resembling the reversible on-off blinking of the emission observed for larger CdSe nanocrystals.

10.
Biochim Biophys Acta ; 1512(2): 259-72, 2001 Jun 06.
Article in English | MEDLINE | ID: mdl-11406103

ABSTRACT

This paper describes a new method for enhancing the interaction of liposomes with cells. A novel class of cationic poly(ethyleneglycol) (PEG)-lipid (CPL) conjugates have been characterized for their ability to insert into pre-formed vesicles and enhance in vitro cellular binding and uptake of neutral and sterically-stabilized liposomes. The CPLs, which consist of a distearoylphosphatidylethanolamine (DSPE) anchor, a fluorescent dansyl moiety, a heterobifunctional PEG polymer (M(r) 3400), and a cationic headgroup composed of lysine derivatives, have been described previously [Bioconjug. Chem. 11 (2000) 433]. Five separate CPL, possessing 1-4 positive charges in the headgroup (referred to as CPL(1)-CPL(4), respectively), were incubated (as micellar solutions) in the presence of neutral or sterically-stabilized cationic large unilamellar vesicles (LUVs), and were found to insert into the external leaflet of the LUVs in a manner dependent on temperature, time, CPL/lipid ratio, and LUV composition. For CPL/lipid molar ratios < or =0.1, optimal insertion levels of approximately 70% of initial CPL were obtained following 3 h at 60 degrees C. The insertion of CPL resulted in aggregation of the LUVs, as assessed by fluorescence microscopy, which could be prevented by the presence of 40 mM Ca(2+). The effect of CPL-insertion on the binding of LUVs to cells was examined by fluorescence microscopy and quantified by measuring the ratio of rhodamine fluorescence to protein concentration. Neither control LUVs or LUVs containing CPL(2) displayed significant uptake by BHK cells. However, a 3-fold increase in binding was observed for LUVs possessing CPL(3), while for CPL(4)-LUVs values as high as 10-fold were achieved. Interestingly, the increase in lipid uptake did not correlate with total surface charge, but rather with increased positive charge density localized at the CPL distal headgroups. These results suggest that incorporation of CPLs into existing liposomal drug delivery systems may lead to significant improvements in intracellular delivery of therapeutic agents.


Subject(s)
Glycerophospholipids/pharmacokinetics , Liposomes/pharmacokinetics , Phosphatidylcholines/pharmacokinetics , Phosphatidylethanolamines/pharmacokinetics , Polyethylene Glycols/pharmacokinetics , Animals , Biological Transport , Cell Line , Cricetinae , Glycerophospholipids/chemistry , Kidney , Kinetics , Liposomes/chemistry , Models, Molecular , Molecular Conformation , Phosphatidylcholines/chemistry , Phosphatidylethanolamines/chemistry , Polyethylene Glycols/chemistry , Quaternary Ammonium Compounds/pharmacokinetics
11.
Curr Opin Mol Ther ; 3(2): 153-8, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11338928

ABSTRACT

The development of vectors capable of treating systemic diseases is an important goal for gene therapy protocols. In order for a carrier system to preferentially accumulate at sites of systemic disease, such as tumors, sites of inflammation and sites of infection, the carrier must exhibit long circulation lifetimes following intravenous injection. Unfortunately, most gene delivery systems, including viral vectors as well as non-viral vectors, e.g., lipoplexes, polyplexes and lipopolyplexes, are rapidly cleared from the circulation and are preferentially taken up by the 'first-pass' organs such as liver, lung and spleen. Here we review recent literature concerning the ability of non-viral vectors to act as systemic gene therapy agents. The most promising systemic vectors are liposomal systems in which plasmid DNA is encapsulated within a lipid bilayer. The stabilized plasmid-lipid particle (SPLP) system, for example, exhibits circulation half-lives of the order of 6 h following intravenous injection, and preferentially accumulates in distal tumors with gene expression primarily localized to the tumor site.


Subject(s)
Gene Transfer Techniques , Genetic Therapy , Genetic Vectors , Animals , DNA/genetics , DNA/metabolism , Genes, Reporter , Humans , Lipid Metabolism , Liposomes/chemistry , Plasmids , Polymers/metabolism
12.
Inorg Chem ; 40(7): 1459-65, 2001 Mar 26.
Article in English | MEDLINE | ID: mdl-11261951

ABSTRACT

Three ruthenium sulfide clusters with labile CH3CN ligands have been photochemically synthesized. Irradiation of [(cymene)3Ru3S2](PF6)2 ([1](PF6)2) in CH3CN gives [(cymene)2(CH3CN)3Ru3S2](PF6)2 ([2](PF6)2), which has been characterized by 1H NMR spectroscopy, ESI mass spectrometry, and chemical reactivity. Treatment of [2](PF6)2 with PPh3 gives [(cymene)2(CH3CN)2(PPh3)Ru3S2](PF6)2 ([3](PF6)2) and [(cymene)2(CH3CN)(PPh3)2Ru3S2](PF6)2 ([4](PF6)2), while treatment with 1,4,7-trithiacyclononane (9S3) gives [(cymene)2(9S3)Ru3S2](PF6)2 ([5](PF6)2). A crystallographic study demonstrated that the Ru3 core in [3](PF6)2, [4](PF6)2, and [5](PF6)2 is distorted with a pair of elongated Ru-Ru bonds. Cyclic voltammetry shows that [3](PF6)2 and [4](PF6)2 undergo two closely spaced reversible one-electron reductions whereas [5](PF6)2 undergoes one irreversible one-electron reduction and one reversible one-electron reduction. Prolonged irradiation of [1](PF6)2 in CH3CN causes decomposition, resulting in the pentanuclear cluster [(cymene)4Ru5S4](PF6)2 ([6](PF6)2).

14.
Angew Chem Int Ed Engl ; 39(10): 1857-1860, 2000 May 15.
Article in English | MEDLINE | ID: mdl-10934386
15.
Chemistry ; 6(12): 2103-11, 2000 Jun 16.
Article in English | MEDLINE | ID: mdl-10926214

ABSTRACT

The multisubunit ligand 2 combines two complexation substructures known to undergo, with specific metal ions, distinct self-assembly processes to form a double-helical and a grid-type structure, respectively. The binding information contained in this molecular strand may be expected to generate, in a strictly predetermined and univocal fashion, two different, well-defined output inorganic architectures depending on the set of metal ions, that is, on the coordination algorithm used. Indeed, as predicted, the self-assembly of 2 with eight CuII and four CuI yields the intertwined structure D1. It results from a crossover of the two assembly subprograms and has been fully characterized by crystal structure determination. On the other hand, when the instructions of strand 2 are read out with a set of eight CuI and four MII (M = Fe, Co, Ni, Cu) ions, the architectures C1-C4, resulting from a linear combination of the two subprograms, are obtained, as indicated by the available physico-chemical and spectral data. Redox interconversion of D1 and C4 has been achieved. These results indicate that the same molecular information may yield different output structures depending on how it is processed, that is, depending on the interactional (coordination) algorithm used to read it. They have wide implications for the design and implementation of programmed chemical systems, pointing towards multiprocessing capacity, in a one code/ several outputs scheme, of potential significance for molecular computation processes and possibly even with respect to information processing in biology.

16.
Bioconjug Chem ; 11(3): 433-7, 2000.
Article in English | MEDLINE | ID: mdl-10821661

ABSTRACT

The synthesis of a new class of fluorescent cationic poly(ethylene glycol) lipid conjugates (CPLs) is described. These lipids consist of a hydrophobic distearoyl-phosphatidylethanolamine (DSPE) anchor coupled to a highly fluorescent N(epsilon)-dansyl lysine moiety, which is attached to a hydrophilic poly(ethylene glycol) (PEG) spacer that is linked to a cationic headgroup made of lysine residues. Introduction of the dansyl moiety allows rapid and accurate quantification of CPLs within lipid bilayers using fluorescence techniques. The synthetic scheme is straightforward, using repeated amino-carboxyl coupling reaction steps, with purification by precipitation. A series of dansylated CPLs was synthesized with zero, one, three, and seven lysine residues located at the distal end of the PEG chain, giving rise to CPLs with one, two, four, and eight distal positive charges, respectively. The structures of the CPLs were confirmed by (1)H NMR spectroscopy and chemical analysis. CPLs provide a means of introducing positive charge to a bilayer that is localized some distance from the membrane surface, and are of particular interest for nonviral gene delivery applications. The usefulness of CPLs is demonstrated by the enhanced in vitro cellular binding and uptake of liposomes containing CPL(4).


Subject(s)
Cations , Fluorescent Dyes , Lipids/chemistry , Polyethylene Glycols/chemistry , Electrochemistry , Indicators and Reagents , Lipid Bilayers/chemistry , Lysine/analogs & derivatives , Lysine/chemistry , Magnetic Resonance Spectroscopy , Molecular Structure , Phosphatidylethanolamines/chemistry
17.
Chemistry ; 6(3): 545-51, 2000 Feb 04.
Article in English | MEDLINE | ID: mdl-10747422

ABSTRACT

The silylated derivative of thiophosphoric acid (S)P(SSiMe3)3 is used as a convenient starting compound for the synthesis of multinuclear Cu and Au cluster complexes. (S)P(SSiMe3)3 reacts with CuCI/PPh3 and [AuCClPPh3] to give the following compounds: [Cu4(P2S6)(PPh3)4] (1), [Cu6(P2S6)Cl2-(PPh3)6] (2) and [Au4(P2S6)(PPh3)4](3). According to X-ray structure determination, these compounds contain P2S6(4-) ions, in which S atoms act as ligands for Cu+ and Au+ ions. Although 1 and 3 have the same stoichiometry, bonding of the metal ions to the P2S6 skeleton displays small but remarkable differences. Au is twofold coordinated, whereas Cu shows a threefold coordination. Ab initio calculations have been carried out to rationalise these structural differences. The theoretical treatment of the corresponding Ag compound indicates the latter to be less stable.

18.
Chemistry ; 6(22): 4132-9, 2000 Nov 17.
Article in English | MEDLINE | ID: mdl-11128276

ABSTRACT

The synthesis and X-ray structures of three metal complexes with terpyridine-derived ligands that contain amino-pyrimidine and amino-pyrazine moieties are presented. They have been designed in view of directing their self-assembly into specific supramolecular arrays through molecular recognition interactions. The solid-state structures indeed reveal extensive hydrogen-bonded networks. The Co complex 4a with PF6- counterions builds a two-dimensional infinite interwoven grid through strong double hydrogen bonds (d(N-H-N) =2.918-3.018 A) between the amino groups and the N atoms of the rings, with all H-bonding sites saturated. Changing the anions to BF4- in 4b leads to a similar infinite but partially broken grid with a quarter of the H-bonding sites unsaturated (d(N-H-N)=2.984-3.206 A). In the case of the Zn complex 12 with triflate anions, half of the hydrogen bonds are formed. Only one of the two orthogonal ligands has hydrogen bonds (d(N-H-N) = 3.082, 3.096 A) to the neighbouring complexes and thus builds linear, supramolecular, polymeric chains. These structural differences are mainly attributed to crystal-packing effects caused by the different anions. The data presented here may also be regarded as a prototype for the generation of organised arrays through sequential self-assembly processes.

19.
Chemistry ; 6(22): 4140-8, 2000 Nov 17.
Article in English | MEDLINE | ID: mdl-11128277

ABSTRACT

Ligand 3 has been shown to self-assemble under coordination of copper(II) cations in a 1:1 ratio in acetonitrile to give equilibrating mixtures of a [2 x 2] grid-type tetranuclear structure 1 and a hexanuclear achitecture of hexagonal shape 2. The latter was confirmed by determination of the crystal structure which further indicated that 2 contained acetonitrile molecules and hydroxo groups bound to the copper(II) centers, which are therefore five-coordinate. The structures assigned to 1 and 2 were further supported by the spectral (mass, UV/Vis) data. The self-assembly process is strongly dependent on the conditions of the medium. An increase in concentration in acetronitrile increases the relative amount of hexamer 2, which appears to be the favored entity at the highest concentrations that can be reached before precipitation occurs. On the other hand, in nitromethane only the tetranuclear complex 1 was detected by mass spectrometry. Replacement of nitromethane by acetonitrile and vice versa indicated the reversible switching between a solution containing either 1 alone or an equilibrium mixture of 1 and 2, respectively. In conclusion, the system described presents several remarkable features: 1) self-assembly with substrate binding, 2) dynamic combinatorial structure generation, and 3) environment-induced structural switching amounting in effect to a process of adaptive self-assembly.

20.
Chemistry ; 6(24): 4510-7, 2000 Dec 15.
Article in English | MEDLINE | ID: mdl-11192084

ABSTRACT

Coordination of the pentatopic ligand 3 with AgI leads to the simultaneous self-assembly of two polynuclear architectures: a [4 x 5] grid-type species 10 and a quadruple-helicate 11, which contain twenty and ten silver ions. respectively. Their structures have been established by X-ray diffraction analysis of the crystals obtained as a mixture on crystallisation. Complex 10 contains two [2 x 5]-AgI10 rectangular subgrids located on opposite sides of an array of parallel ligands of 3 that are twisted into a transoid N=C-C=N arrangement around the central C-C bond; it may thus be formulated as a grid of grids: [2 x (2 x 5)]. Complex 11 is an inorganic quadruple helicate that consists of two sets of two parallel ligands of 3 connected by an array of ten silver ions. Both compounds 10 and 11 are novel types of polynuclear complexes that are composed of two subunits. Their formation points to the possibility of generating specific arrays of metal ions by self-assembly, involving, in particular, a combination of subunits within the overall entity. They represent organised patterns of ion dots of special significance in view of their formal relationship to quantum dots.

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