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Daniel C, Bissinger MC, Courcol RJ. Effects of host iron transport compounds on growth kinetics and outer-membrane protein expression of Bilophila wadsworthia. Anaerobe 2006; 4:103-9. [PMID: 16887629 DOI: 10.1006/anae.1998.0154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/1997] [Accepted: 03/04/1998] [Indexed: 11/22/2022]
Abstract
Since the environmental iron concentration has emerged as an important attribute in the expression of bacterial virulence, the purpose of this study was to determine the effects of transferrin, lactoferrin, heme compounds, and inorganic iron sources (ferric and ferrous sulfate) on the growth of Bilophila wadsworthia and to study its outer membrane composition when grown under these different simulated in vivo conditions. Lactoferrin, transferrin, hemin and hemoglobin supported full growth of the bacteria in media lacking other iron sources. Bilophila wadsworthia was also capable of growing in the presence of ferrous and ferric sulfate. Profiles obtained by SDS-PAGE showed two iron-regulated outer membrane proteins (IROMPs) of 190 kDa and 88 kDa. The 190 kDa was susceptible to proteinase K cleavage in whole cells, indicating its exposure at the cell surface. These two major IROMPs were expressed in iron-restricted media supplemented with iron-bound organic sources and repressed by the addition of inorganic iron sources.
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Daniel C, Repa A, Wild C, Pollak A, Pot B, Breiteneder H, Wiedermann U, Mercenier A. Modulation of allergic immune responses by mucosal application of recombinant lactic acid bacteria producing the major birch pollen allergen Bet v 1. Allergy 2006; 61:812-9. [PMID: 16792578 DOI: 10.1111/j.1398-9995.2006.01071.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
BACKGROUND Probiotic lactic acid bacteria (LAB) are able to modulate the host immune system and clinical trials have demonstrated that specific strains have the capacity to reduce allergic symptoms. Therefore, we aimed to evaluate the potential of recombinant LAB producing the major birch pollen allergen Bet v 1 for mucosal vaccination against birch pollen allergy. METHODS Recombinant Bet v 1-producing Lactobacillus plantarum and Lactococcus lactis strains were constructed. Their immunogenicity was compared with purified Bet v 1 by subcutaneous immunization of mice. Intranasal application of the live recombinant strains was performed to test their immunomodulatory potency in a mouse model of birch pollen allergy. RESULTS Bet v 1 produced by the LAB was recognized by monoclonal anti-Bet v 1 and IgE antibodies from birch pollen-allergic patients. Systemic immunization with the recombinant strains induced significantly lower IgG1/IgG2a ratios compared with purified Bet v 1. Intranasal pretreatment led to reduced allergen-specific IgE vs enhanced IgG2a levels and reduced interleukin (IL)-5 production of splenocytes in vitro, indicating a shift towards non-allergic T-helper-1 (Th1) responses. Airway inflammation, i.e. eosinophils and IL-5 in lung lavages, was reduced using either Bet v 1-producing or control strains. Allergen-specific secretory IgA responses were enhanced in lungs and intestines after pretreatment with only the Bet v 1-producing strains. CONCLUSIONS Mucosal vaccination with live recombinant LAB, leading to a shift towards non-allergic immune responses along with enhanced allergen-specific mucosal IgA levels offers a promising approach to prevent systemic and local allergic immune responses.
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Olafsen A, Daniel C, Schuurman Y, Råberg L, Olsbye U, Mirodatos C. Light alkanes CO2 reforming to synthesis gas over Ni based catalysts. Catal Today 2006. [DOI: 10.1016/j.cattod.2006.02.053] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Rigaux P, Daniel C, Ratajczak C, Pot B, Pestel J, Jacquet A. Immunomodulatory Properties of Recombinant Lactic Acid Bacteria Encoding a Major House-dust Mite Allergen. J Allergy Clin Immunol 2006. [DOI: 10.1016/j.jaci.2005.12.868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Daniel C, Renders L, Amann K, Schulze-Lohoff E, Hauser IA, Hugo C. Mechanisms of everolimus-induced glomerulosclerosis after glomerular injury in the rat. Am J Transplant 2005; 5:2849-61. [PMID: 16302997 DOI: 10.1111/j.1600-6143.2005.01120.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Despite the lack of nephrotoxicity, adverse effects of the new antiproliferative immunosuppressant everolimus have been reported. By varying time point and dose of everolimus treatment as well as the degree of glomerular injury, the specific conditions and potential mechanisms leading to adverse actions in the anti-Thy1 model have been determined. Only the combination of early and high-dose everolimus treatment (1-3 mg/kg bw) with a severe glomerular lesion ('full-dose' anti-Thy1 model) caused adverse effects with a high mortality rate, progressive apoptosis, crescent formation and glomerulosclerosis. In contrast, either later start or low-dose (0.3 mg/kg bw) therapy or treatment of a less severe lesion ('reduced dose' anti-Thy1 model) appeared to be relatively safe for the glomerular architecture. The adverse effects of everolimus were linked to its marked inhibition of endothelial cell, but not necessarily mesangial cell proliferation. In addition, everolimus markedly inhibited the angiogenic cytokine vascular endothelial growth factor in nephritic glomeruli in vivo. These experimental results suggest special caution regarding the use of everolimus in all situations of severe glomerular cell injury requiring extensive capillary repair, where at least adaption to a low dose needs to be considered.
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Vergnenègre A, Daniel C, Léna H, Fournel P, Kleisbauer JP, Le Caer H, Letreut J, Paillotin D, Pérol M, Bouchaert E, Preux PM, Robinet G. Docetaxel and concurrent radiotherapy after two cycles of induction chemotherapy with cisplatin and vinorelbine in patients with locally advanced non-small-cell lung cancer. A phase II trial conducted by the Groupe Francais de Pneumo-Cancerologie (GFPC). Lung Cancer 2005; 47:395-404. [PMID: 15713523 DOI: 10.1016/j.lungcan.2004.08.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2004] [Revised: 08/12/2004] [Accepted: 08/18/2004] [Indexed: 10/26/2022]
Abstract
CONTEXT The most satisfactory treatment for patients with locally advanced non-small-cell lung cancer (NSCLC) is combination chemotherapy-radiotherapy (CT-RT). The optimal treatment modalities remain to be determined. OBJECTIVE We conducted a multicenter phase II trial of the docetaxel-radiotherapy combination after induction chemotherapy with cisplatin-vinorelbine. The main endpoint was the objective response rate. PATIENTS AND METHODS Patient with inoperable stage locally advanced NSCLC received induction chemotherapy consisting of two cycles of cisplatin 100 mg/m2 on D1 and vinorelbine 25 mg/m2 on D1, D8, D15 and D22. Patients with responses or stable disease then received concurrent RT-CT consisting of 25 mg/m2/week docetaxel and single-fraction radiotherapy (66 grays (Gy) in 33 fractions) over 6.5 weeks. RESULTS Fifty-six patients were enrolled from 1 July 2000 to 31 December 2001. Sixteen patients left the trial after induction chemotherapy, eight for progression, five for toxicity, and two for intercurrent events. One patient underwent surgery after induction chemotherapy. In total, 40 of the 56 patients received RT-CT. Twelve (30%) of these 40 patients experienced grade III or IV pulmonary or esophageal toxicity. In the intention-to-treat analysis, the objective response rate was 46.4% (95% CI 33.0-60.2). The median time to progression was 6.2 months [1.1-26.0]. The median survival time was 13 months [0.3-44.9 months]. Nine patients progressed during RT-CT, six with brain metastases. CONCLUSION Weekly docetaxel with concurrent radiotherapy, following chemotherapy is acceptable. The tumor response rate is moderate. Further trials are required to determine the risk-benefit relationship of this treatment schedule, and the possible benefit of adding other cytotoxic drugs.
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Beljonne D, Hennebicq E, Daniel C, Herz LM, Silva C, Scholes GD, Hoeben FJM, Jonkheijm P, Schenning APHJ, Meskers SCJ, Phillips RT, Friend RH, Meijer EW. Excitation Migration along Oligophenylenevinylene-Based Chiral Stacks: Delocalization Effects on Transport Dynamics. J Phys Chem B 2005; 109:10594-604. [PMID: 16852286 DOI: 10.1021/jp050792p] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Atomistic models based on quantum-chemical calculations are combined with time-resolved spectroscopic investigations to explore the migration of electronic excitations along oligophenylenevinylene-based chiral stacks. It is found that the usual Pauli master equation (PME) approach relying on uncoherent transport between individual chromophores underestimates the excitation diffusion dynamics, monitored here by the time decay of the transient polarization anisotropy. A better agreement to experiment is achieved when accounting for excitation delocalization among acceptor molecules, as implemented in a modified version of the PME model. The same models are applied to study light harvesting and trapping in guest-host systems built from oligomers of different lengths.
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Daniel C, Schlauch T, Zügel U, Steinmeyer A, Radeke HH, Steinhilber D, Stein J. 22-ene-25-oxa-vitamin D: a new vitamin D analogue with profound immunosuppressive capacities. Eur J Clin Invest 2005; 35:343-9. [PMID: 15860047 DOI: 10.1111/j.1365-2362.2005.01492.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND The biologic role of 1,25-dihydroxyvitamin D(3), such as anti-inflammatory functions, reduction of cytokine production by T cells and immunoglobulin production by B cells, is well established. However, its clinical use as an immunosuppressive agent is limited because of the hypercalcemic toxicity occurring after systemic application. The purpose of this study was to investigate the immunmodulatory effects of 22-ene-25-oxa-vitamin D (ZK156979), a novel low calcemic vitamin D analogue. MATERIALS AND METHODS Human peripheral blood mononuclear cells (PBMCs) from healthy donors were isolated using the Ficoll Hypaque technique, cultured for 24 h and treated with different concentrations of ZK156979 ranging from 10(-5) to 10(-10) mol L(-1) compared with 1,25-dihydroxyvitamin D(3)[10(-5)-10(-10) mol L(-1)] following phytohaemagglutinin (PHA) stimulation. Interferon gamma (IFNgamma), tumour necrosis factor alpha (TNFalpha), interleukin 1 beta (IL-1beta), interleukin 10 (IL-10) and interleukin 4 (IL-4) secretion in supernatants were measured by ELISA. RESULTS ZK156979 inhibited the PHA-induced Th1-response (IFNgamma and TNFalpha levels) and the macrophage-product IL-1beta in a concentration-dependent manner (10(-10)-10(-5) mol L(-1)) with the efficiency on cytokine expression compared with 1,25-dihydroxyvitamin D(3) being slightly reduced. In contrast, ZK156979 and 1,25-dihydroxyvitamin D(3) both affected the Th2 response, leading to significantly increased IL-10- and IL-4 secretion. CONCLUSIONS ZK156979 is a member of novel vitamin D analogues revealing prominent immunomodulatory and suppressive characteristics with distinctive inhibition of Th1-cytokines whereas the Th2 compartment is augmented, thus providing a considerable therapeutic potential in T-cell -mediated diseases.
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Bayle S, Descourt R, Gouva S, Daniel C, Robinet G. [Efficacy of gefitinib (Iressa) in the treatment of an inoperable bronchioloalveolar cell carcinoma]. Rev Mal Respir 2004; 21:153-7. [PMID: 15260051 DOI: 10.1016/s0761-8425(04)71248-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
INTRODUCTION Bronchioloalveolar cell carcinoma (BAC) is a rare bronchial tumour. At present the only curative treatment is surgery and inoperable cases are often resistant to radio and chemotherapy. CASE REPORT A 76 year old woman was treated surgically for a BAC, stage T2N0M0. Three months later she presented with cough and dyspnoea. Investigation revealed recurrence of the disease with bilateral pulmonarymetastases. She then received two courses of chemotherapy leading, at best, to stabilisation of the disease. At that time the treatment decision was simple observation. Six months later when there was progression of the bilateral lesions treatment was initiated with gefitinib 250 mg daily. This lead to rapid improvement in the clinical symptoms and the chest x-ray and CT scan showed evidence of a partial response that persisted one year after the beginning of treatment. CONCLUSION This observation describes the effect of gefitinib in the treatment of inoperable BAC for which there is, at present, no effective therapy.
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Zális S, Amor NB, Daniel C. Influence of the Halogen Ligand on the Near-UV−Visible Spectrum of [Ru(X)(Me)(CO)2(α-diimine)] (X = Cl, I; α-Diimine = Me-DAB, iPr-DAB; DAB = 1,4-Diaza-1,3-butadiene): An ab Initio and TD-DFT Analysis. Inorg Chem 2004; 43:7978-85. [PMID: 15578835 DOI: 10.1021/ic049464e] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The near-UV-vis electronic spectroscopy of [Ru(X)(Me)(CO)(2)(iPr-DAB)] (X = Cl or I; iPr-DAB = N,N'-di-isopropyl-1,4-diaza-1,3-butadiene) is investigated through CASSCF/CASPT2 and TD-DFT calculations on the model complexes [Ru(X)(Me)(CO)(2)(Me-DAB)] (X = Cl or I). Convergence of the calculated transition energies for the low-lying metal-to-ligand charge-transfer (MLCT), X-to-ligand charge-transfer (XLCT, X halide ligand), or sigma-bond-to-ligand charge-transfer (SBLCT) to experimental values is analyzed for both methods. On the basis of these accurate calculations, it is shown that whereas the lowest singlet state can be assigned to a nearly pure XLCT state in [Ru(I)(Me)(CO)(2)(Me-DAB)], its character is mainly MLCT in [Ru(Cl)(Me)(CO)(2)(Me-DAB)]. These results are in agreement with time-resolved emission/IR and resonance Raman experimental data. The experimental UV-vis bands are well reproduced by the CASSCF/CASPT2 calculations. The TD-DFT transition energies to the long-range charge transfer states are dramatically affected by the nature of the functional, with lowering leading to meaningless values in the case of nonhybrid functionals. Both methods reproduce well the red shift of the absorption bands on going from the chloride to the iodide complex as well as the shift of the strongly absorbing higher MLCT transition from the visible to the UV domain of energy.
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Pérez-Ramírez J, Gallardo-Llamas A, Daniel C, Mirodatos C. N2O-mediated propane oxidative dehydrogenation over Fe-zeolites. TEOM studies for continuous propylene production in a cyclically-operated reactor. Chem Eng Sci 2004. [DOI: 10.1016/j.ces.2004.07.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Rosell R, Daniel C, Ramlau R, Szczesna A, Constenla M, Mennecier B, Pfeifer W, Mueser M, Montaner I, Gatzemeier U. Randomized phase II study of cetuximab in combination with cisplatin (C) and vinorelbine (V) vs. CV alone in the first-line treatment of patients (pts) with epidermal growth factor receptor (EGFR)-expressing advanced non-small-cell lung cancer (NSCLC). J Clin Oncol 2004. [DOI: 10.1200/jco.2004.22.90140.7012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Cottee LJ, Daniel C, Loh WS, Harrison BM, Burke W. Remyelination and recovery of conduction in cat optic nerve after demyelination by pressure. Exp Neurol 2003; 184:865-77. [PMID: 14769379 DOI: 10.1016/s0014-4886(03)00310-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2000] [Revised: 06/11/2003] [Accepted: 06/13/2003] [Indexed: 11/28/2022]
Abstract
Pressure has been applied to the optic nerve of cats sufficient to block conduction in the large (Y) nerve fibers. The pressure block produces a mixture of axotomy and demyelination. By means of implanted electrodes, recovery of conduction in these fibers was monitored. There is a short-term recovery starting about 2 weeks after block induction and finishing at about 4 weeks. A later recovery starts at about 6-7 weeks and finishes at about 10-11 weeks. The remyelination has been monitored in the electron microscope by measurement of the myelin thickness and axon diameter of the large fibers. The remyelination follows a time course similar to the late phase of conduction recovery. By reference to the work of others, we surmise that the early recovery of conduction is due to the reorganization of microtubules disorganized by the pressure.
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Fizazi K, Doubre H, Le Chevalier T, Riviere A, Viala J, Daniel C, Robert L, Barthélemy P, Fandi A, Ruffié P. Combination of raltitrexed and oxaliplatin is an active regimen in malignant mesothelioma: results of a phase II study. J Clin Oncol 2003; 21:349-54. [PMID: 12525529 DOI: 10.1200/jco.2003.05.123] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE The aim of this open-label phase II study was to evaluate the activity of raltitrexed (Tomudex; AstraZeneca, Cergy, France) and oxaliplatin combination therapy in patients with diffuse malignant pleural mesothelioma. PATIENT AND METHODSs: Fifteen pretreated and 55 chemotherapy-naive patients (median age, 60 years; World Health Organization performance status of < or = 2) were enrolled. Most patients (66%) had advanced disease. Patients received raltitrexed 3 mg/m2 followed by oxaliplatin 130 mg/m2 every 3 weeks. RESULTS Twenty-four patients (34%) were classified as having a poor prognosis. In the overall study population, 14 patients (20%) had a partial response, and 32 patients (46%) had stable disease. The symptomatic response rates were as follows: shortness of breath, 36%; pain, 30%; activity, 23%; appetite, 21%; and asthenia, 20%. Median time to disease progression was 18 weeks (95% confidence interval [CI], 13 to 22 weeks). In chemotherapy-naive patients, median survival was 31 weeks (95% CI, 23 to 40 weeks) from the start of treatment and 49 weeks (95% CI, 40 to 52 weeks) from diagnosis of mesothelioma. In pretreated patients, median survival was 44 weeks (95% CI, 24 to 40 weeks) from the start of treatment and 226 weeks (95% CI, 63 to 292 weeks) from the diagnosis of mesothelioma. Overall 1-year survival was 26% (95% CI, 15.5% to 36.4%), survival was 22% (95% CI, 10.9% to 33.2%) in chemotherapy-naive patients and 40% (95% CI, 15.2% to 64.8%) in pretreated patients. Hematologic toxicity was mild, and there was no alopecia. The most common adverse events were asthenia, nausea/vomiting, and paraesthesia, and no treatment-related deaths were reported. CONCLUSION The raltitrexed and oxaliplatin combination is an active outpatient regimen in malignant mesothelioma and has an acceptable tolerability profile.
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Vallet V, Bossert J, Strich A, Daniel C. The electronic spectroscopy of transition metal di-hydrides H2M(CO)4(M = Fe,Os): a theoretical study based on CASSCF/MS-CASPT2 and TD-DFT. Phys Chem Chem Phys 2003. [DOI: 10.1039/b303239f] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Daniel C, Kolba E, Lehr L, Manz J, Schroeder T. Photodissociation Dynamics of Organometallic Complexes: Model Simulation for H + Co(CO)4 .rarw. HCo(CO)4 .fwdarw. HCo(CO)3 + CO. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100090a016] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Daniel C, Veillard A. Theoretical study of the cis-trans isomerism in disubstituted d6 metal carbonyls. Inorg Chem 2002. [DOI: 10.1021/ic00305a029] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Daniel C, Heitz MC, Lehr L, Manz J, Schroeder T. Polanyi rules for ultrafast unimolecular reactions: simulations for HCo(CO)4(1E)* .fwdarw. hydrogen atom + cobalt tetracarbonyl. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100150a007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Koga N, Daniel C, Han J, Fu XY, Morokuma K. Potential energy profile of a full catalytic cycle of olefin hydrogenation by the Wilkinson catalyst. J Am Chem Soc 2002. [DOI: 10.1021/ja00245a044] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Daniel C, Koga N, Han J, Fu XY, Morokuma K. Ab initio MO study of the full catalytic cycle of olefin hydrogenation by the Wilkinson catalyst RhCl(PR3)3. J Am Chem Soc 2002. [DOI: 10.1021/ja00220a010] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Matsubara T, Daniel C, Veillard A. Photosubstitution of d6 Metal Carbonyls M(CO)5L Revisited: A Theoretical Study. Organometallics 2002. [DOI: 10.1021/om00024a037] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Turki M, Daniel C, Zális S, Vlcek A, van Slageren J, Stufkens DJ. UV-visible absorption spectra of [Ru(E)(E')(CO)(2)(iPr-DAB)] (E = E' = SnPh(3) or Cl; E = SnPh(3) or Cl, E' = CH(3); iPr-DAB = N,N'-Di-isopropyl-1,4-diaza-1,3-butadiene): combination of CASSCF/CASPT2 and TD-DFT calculations. J Am Chem Soc 2001; 123:11431-40. [PMID: 11707120 DOI: 10.1021/ja010782b] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The UV-visible absorption spectra of [Ru(E)(E')(CO)(2)(iPr-DAB)] (E = E' = SnPh(3) or Cl; E = SnPh(3) or Cl, E' = CH(3); iPr-DAB = N,N'-di-isopropyl-1,4-diaza-1,3-butadiene) are investigated using CASSCF/CASPT2 and TD-DFT calculations on model complexes [Ru(E)(E')(CO)(2)(Me-DAB)] (E = E' = SnH(3) or Cl; E = SnH(3) or Cl, E' = CH(3); Me-DAB = N,N'-dimethyl-1,4-diaza-1,3-butadiene). The calculated transition energies and oscillator strengths allow an unambiguous assignment of the spectra of the nonhalide complexes [Ru(SnPh(3))(2)(CO)(2)(iPr-DAB)] and [Ru(SnPh(3))(Me)(CO)(2)(iPr-DAB)]. The agreement between the CASSCF/CASPT2 and TD-DFT approaches is remarkably good in the case of these nonhalide complexes. The lowest-energy part of the spectrum (visible absorption) originates in electronic transitions that correspond to excitations from the axial E-Ru-E' sigma(2) orbital into the low-lying pi(DAB) orbital (sigma-bond-to-ligand charge transfer, SBLCT, transitions), while the absorption between 25 000 and 35 000 cm(-1) is due to metal-to-ligand charge transfer (MLCT) excitations from the 4d(Ru) orbitals to pi(DAB) (MLCT). Above 35 000 cm(-1), the transitions mostly correspond to MLCT and SBLCT excitations into pi(CO) orbitals. Analysis of the occupied sigma orbitals involved in electronic transitions of the nonhalide complexes shows that the Kohn-Sham orbitals are generally more delocalized than their CASSCF/CASPT2 counterparts. The CASSCF/CASPT2 and TD-DFT approaches lead to different descriptions of electronic transitions of the halide complexes [Ru(Cl)(2)(CO)(2)(Me-DAB)] and [Ru(Cl)(Me)(CO)(2)(Me-DAB)]. CASSCF/CASPT2 reproduces well the observed blue-shift of the lowest absorption band on going from the nonhalide to halide complexes. TD-DFT systematically underestimates the transition energies of these complexes, although it reproduces the general spectral features. The CASSCF/CASPT2 and TD-DFT techniques differ significantly in their assessment of the chloride contribution. Thus, CASSCF/CASPT2 assigns the lowest-energy absorption to predominantly Ru --> DAB MLCT transitions, while TD-DFT predicts a mixed XLCT/MLCT character, with the XLCT component being predominant. (XLCT stands for halide (X)-to-ligand-charge transfer.) Analysis of Kohn-Sham orbitals shows a very important 3p(Cl) admixture into the high-lying occupied orbitals, in contrast to the CASSCF/CASSPT2 molecular orbitals which are nearly pure 4d(Ru) with the usual contribution of the back-donation to pi(CO) orbitals. Further dramatic differences were found between characters of the occupied sigma orbitals, as calculated by CASSCF/CASPT2 and DFT. They differ even in their bonding character with respect to the axial E-Ru and Cl-Ru bonds. These differences are attributed to a drawback of the DFT technique with respect to the dynamical correlation effects which become very important in complexes with a polar Ru-Cl bond. Similar differences in the CASSCF/CASPT2 and TD-DFT descriptions of the lowest allowed transition of [Ru(Cl)(2)(CO)(2)(Me-DAB)] and [Ru(Cl)(Me)(CO)(2)(Me-DAB)] were found by comparing the changes of Mulliken population upon excitation. This comparison also reveals that CASSCF/CASPT2 generally predicts smaller electron density redistribution upon excitation than TD-DFT, despite the more localized character of CASSCF/CASPT2 molecular orbitals.
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