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van Bommel KJ, de Jong MR, Metselaar GA, Verboom W, Huskens J, Hulst R, Kooijman H, Spek AL, Reinhoudt DN. Complexation and (templated) synthesis of rhenium complexes with cyclodextrins and cyclodextrin dimers in water. Chemistry 2001; 7:3603-15. [PMID: 11560332 DOI: 10.1002/1521-3765(20010817)7:16<3603::aid-chem3603>3.0.co;2-e] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Several small, lipophilic rhenium complexes form inclusion complexes with native beta-cyclodextrin (beta-CD) and beta-CD dimers. Association constants larger than 10(9)M(-1) were obtained using dimers. The use of beta-CD also enabled the synthesis of these rhenium complexes in water, in excellent yields, through complexation of the otherwise insoluble corresponding ligands. The influence of the reaction time and temperature on the configuration of the reaction products has been investigated in depth for one of these complexes. Using a beta-CD dimer, it proved possible to specifically template the formation of one configuration. The strength of the complexes of the rhenium complexes in cyclodextrin dimers may allow radiolabeling of biomolecules.
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Hoogenraad M, Ramkisoensing K, Driessen WL, Kooijman H, Spek AL, Bouwman E, Haasnoot JG, Reedijk J. Catalytic and electrochemical properties of new manganese(III) compounds of 2-(2′-hydroxyphenyl)-oxazoline (Hphox or HClphox). Molecular structures of [Mn(Clphox)2(MeOH)2](ClO4) and [Mn(phox)2(MeOH)2][Mn(phox)2(ClO4)2](H2O)2. Inorganica Chim Acta 2001. [DOI: 10.1016/s0020-1693(01)00485-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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153
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Freund M, Adwan M, Kooijman H, Heiland S, Thomsen M, Hähnel S, Jensen K, Gerner HJ, Sartor K. [Measurement of CSF flow in the spinal canal using MRI with an optimized MRI protocol: experimental and clinical studies]. ROFO-FORTSCHR RONTG 2001; 173:306-14. [PMID: 11367838 DOI: 10.1055/s-2001-12463] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
PURPOSE Measurement of the oscillating CSF flow in the spinal canal (SC) of healthy volunteers and in patients with post-traumatic syringomyelia (PTS) using an optimized MRI protocol as well as to determine whether stenosis induced velocity changes are detectable using MRI. METHODS In 68 healthy volunteers quantitative studies of CSF flow in the cervical, thoracic, and lumbar regions were performed. First, an optimized sequence was developed and tested in 19 volunteers using four different flow-encoding velocities (4, 8, 12, 16 cm/s). Secondly, the optimized sequence was employed in 49 volunteers to measure the different CSF patterns in the cervical, thoracic, and lumbar spinal canals (CSC, TSC, LSC). Part three of the study, in which patients with PTS are being examined is still underway. We measured the maximum velocity (cm/s), the pixel area (mm2), and the stroke volume (ml/s). Using a flow model the velocities prior to and after compression with 5 different power levels were measured at the stenosis and at a distance of 70 cm. RESULTS A total of 226 dynamic measurements have been performed--so far 76 in the first part (62 = 81.5% evaluable) and 150 in the second part--using the optimized sequence and optimal flow velocities. A flow-encoding sequence of 12 cm/s was found best in the CSC and one of 6 cm/s in the TSC and LSC. The maximum velocity in the CSC was 0.95 cm/s with the flow being directed caudal and 0.38 cm/s with the flow being directed cranial. In the TSC the values were 4.7 cm/s and 1.65 cm/s and in the LSC 0.96 cm/s and 0.59 cm/s. The highest velocities were found at the TSC, which has the smallest diameter compared to the CSC and LSC. In the 4 patients with PTS, the maximum velocities were between 0.09 cm/s and 0.97 cm/s with the flow being directed cranial and between 0.04 cm/s and 1.03 cm/s with the flow being directed caudal. The stroke volumina in the CSC were between 0.1 and 1.23 ml/s (mean: 0.48 ml/s) and 0.2 and 2.45 ml/s (mean: 0.66 ml/s) in the TSC and in the LSC 0.08 ml/s and 0.67 ml/s (mean: 0.29 ml/s). The results of the flow model studies showed an increase of velocity between 2.06 and 4.94 cm/s (mean: 3.31 cm/s) at the stenosis and 1.1 and 1.33 cm/s (mean: 1.23 cm/s) at a distance of 70 cm. CONCLUSION Quantitative measurement of the oscillating CSF flow in the entire spinal canal (SC) is possible using an optimized MRI protocol as well as to detect stenosis induced velocity changes. Due to the high interindividual variability in the data of spinal CSF dynamics, further studies are necessary to collect normal data. The detection of movement of CSF in a post-traumatic spinal cord lesion may alter the therapeutic management.
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van den Broeke J, Lutz M, Kooijman H, Spek AL, Deelman BJ, van Koten G. Increasing the Lipophilic Character of Tetraphenylborate Anions through Silyl Substituents. Organometallics 2001. [DOI: 10.1021/om0009177] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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155
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Karstens WF, Stol M, Rutjes FP, Kooijman H, Spek AL, Hiemstra H. Palladium catalyzed cyclization reactions of acetylenic lactams. J Organomet Chem 2001. [DOI: 10.1016/s0022-328x(00)00935-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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156
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van Staveren DR, van Albada GA, Haasnoot JG, Kooijman H, Maria Manotti Lanfredi A, Nieuwenhuizen PJ, Spek AL, Ugozzoli F, Weyhermüller T, Reedijk J. Increase in coordination number of lanthanide complexes with 2,2′-bipyridine and 1,10-phenanthroline by using β-diketonates with electron-withdrawing groups. Inorganica Chim Acta 2001. [DOI: 10.1016/s0020-1693(01)00334-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Beyersdorff D, Schiemann T, Taupitz M, Kooijman H, Hamm B, Nicolas V. Sectional depiction of the pelvic floor by CT, MR imaging and sheet plastination: computer-aided correlation and 3D model. Eur Radiol 2001; 11:659-64. [PMID: 11354764 DOI: 10.1007/s003300000561] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The structures of the pelvic floor are clinically important but difficult to assess. To facilitate the understanding of the complicated pelvic floor anatomy on sectional images obtained by CT and MR imaging, and to make the representation more vivid, a computer-aided 3D model was created from a male and a female torso to develop a teaching tool. A male and a female cadaver torso were investigated by means of CT, MR imaging, and serial-section sheet plastination. A 3D reconstruction of the pelvic floor and adjacent structures was performed by fusion of CT and MR imaging data sets with sheet plastination sections. Corresponding sections from all three methods could be compared and visualized in their 3D context. Sheet plastination allows distinction of connective tissue, muscles, and pelvic organs down to a microscopic level. In combination with CT, MR imaging, and sheet plastination a 3D model of the pelvic floor offers a better understanding of the complex pelvic anatomy. This knowledge may be applied in the diagnostic imaging of urinary incontinence or prolapse and prior to prostate surgery.
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158
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Wijsman GW, Iglesias GA, de Wolf WH, Beekman MC, Bickelhaupt F, Kooijman H, Spek AL. X-ray crystal structures and conformational analysis of bicyclo[5.3.1]undec-1(11)-enes: twisting versus pyradidalization in anti-bredt olefins. J Org Chem 2001; 66:1216-27. [PMID: 11312951 DOI: 10.1021/jo0013195] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of several 9,11,11-trihalo[5.3.1]propellanes and their 4-dimethylsila analogues is described. They solvolyze under formation of the corresponding isomeric 7,9,11- trihalobicyclo[5.3.l]undec-1(11)-enes which are "anti-Bredt" olefins with a strained trans double bond in a bridged eight-membered ring; in the presence of nucleophiles such as water or ethanol, the corresponding 7-hydroxy or 7-ethoxy derivatives, respectively, are obtained. On the basis of the X-ray crystal structures of four of these compounds (1a, 9a, 15, 17b), the effect of strain and of the substitution pattern on the degree of twisting and pyramidalization of the double bond is discussed.
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Velders A, van der Geest B, Kooijman H, Spek A, Haasnoot J, Reedijk J. Ruthenium(III) Coordination to the Exocyclic Nitrogen of 9-Methyladenine and Stabilisation of the Rare Imine Tautomer by Intramolecular Hydrogen Bonding. Eur J Inorg Chem 2001. [DOI: 10.1002/1099-0682(200102)2001:2<369::aid-ejic369>3.0.co;2-n] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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160
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Rohrschneider WK, Hoffend J, Becker K, Darge K, Wunsch R, Clorius JH, Kooijman H, Tröger J. [Static-dynamic MR urography. Comparison with excretory urography and scintigraphy in experimentally-induced urinary tract obstruction]. Radiologe 2001; 41:154-67. [PMID: 11253101 DOI: 10.1007/s001170050958] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To assess the diagnostic value of combined static-dynamic MR urography (MRU) for the functional-morphological evaluation of experimentally induced urinary tract obstruction. METHODS Static-dynamic MRU--combination study with a respiratory-triggered 3D-IR-TSE sequence and a dynamic 2D-FFE sequence after Gd-DTPA and furosemide--was obtained in comparison with 99mTc-MAG3 diuretic renal scintigraphy (DRS), excretory urography (EU) and ultrasound (US) in 29 healthy piglets and in 20 piglets with surgically induced ureteric stenosis (total of 50 postoperative examination blocks). RESULTS MRU allowed complete depiction of the urinary tract in all controls, in operated piglets the stenosis was always correctly identified. Quality of MRU was superior to EU in 36 of 43 comparative studies. Calculation of single kidney function from parenchymal renograms, and assessment of urinary excretion from whole-kidney renograms resulted in a highly significant agreement of MRU with DRS. CONCLUSION Static-dynamic MR urography allows excellent depiction of experimentally induced urinary tract obstruction, and reliable assessment of individual renal function and urinary excretion. Two advantages of the method stand out, it does not require radiation and it permits a functional-morphological correlation.
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Kleij AW, Klein Gebbink RJM, van den Nieuwenhuijzen PAJ, Kooijman H, Lutz M, Spek AL, van Koten G. Halide-Assisted Macrocyclic Ring Formation in Cyclometalated Carbosilane Dendrimers with 1-[C6H3(CH2NMe2)-4-(PdCl)-3] Peripheral Groups: Application as Aldol Condensation Catalysts. Organometallics 2001. [DOI: 10.1021/om000647s] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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162
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van Koningsbruggen PJ, Garcia Y, Kooijman H, Spek AL, Haasnoot JG, Kahn O, Linares J, Codjovi E, Varret F. A new 3-D polymeric spin transition compound: [tris(1,4-bis(tetrazol-1-yl)butane-N1,N 1′)iron(II)] bis(perchlorate). ACTA ACUST UNITED AC 2001. [DOI: 10.1039/b008073j] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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163
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Pieterse K, Vekemans JA, Kooijman H, Spek AL, Meijer EW. Ladderlike oligomers; intramolecular hydrogen bonding, push-pull character, and electron affinity. Chemistry 2000; 6:4597-603. [PMID: 11192093 DOI: 10.1002/1521-3765(20001215)6:24<4597::aid-chem4597>3.0.co;2-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Symmetrical 2,5-bis(2-aminophenyl)pyrazines have been synthesized by application of the Stille coupling strategy. These cotrimers feature three important properties, namely strong intramolecular hydrogen bonding, push-pull character, and high electron affinity. The presence of intramolecular hydrogen bonds has been confirmed by 1H NMR, IR spectroscopy, and single-crystal X-ray diffraction. The hydrogen bond strength can be increased by substituting the amino groups with stronger electron-withdrawing functionalities. Despite the anticipated enhanced pi-conjugation through planarization, a hypsochromic shift was observed in the UV/Vis spectra, explained by a decrease in push-pull character. The electron affinity of the cotrimers was deduced from the first reduction potentials measured by cyclic voltammetry and is related to the electron-withdrawing character of the amino substituents. The results obtained have been compared with those of the corresponding 4-aminophenyl analogues and show that intramolecular hydrogen bonds can be used to design polymers with enhanced pi conjugation as well as a high electron affinity.
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Manen HJ, Nakashima K, Shinkai S, Kooijman H, Spek A, Veggel F, Reinhoudt D. Coordination Chemistry of SCS PdII Pincer Systems. Eur J Inorg Chem 2000. [DOI: 10.1002/1099-0682(200012)2000:12<2533::aid-ejic2533>3.0.co;2-e] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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165
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de Loos M, Ligtenbarg A, van Esch J, Kooijman H, Spek A, Hage R, Kellogg R, Feringa B. Tripodal Tris-Urea Derivatives as Gelators for Organic Solvents. European J Org Chem 2000. [DOI: 10.1002/1099-0690(200011)2000:22<3675::aid-ejoc3675>3.0.co;2-k] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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166
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van Bommel KJ, Verboom W, Hulst R, Kooijman H, Spek AL, Reinhoudt DN. Calix[4]arene rhenium(V) complexes as potential radiopharmaceuticals. Inorg Chem 2000; 39:4099-106. [PMID: 11198865 DOI: 10.1021/ic000172x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The calix[4]arene platform was used for the syntheses of novel rhenium(V) complexes, that may have potential applications as radiopharmaceuticals. The reaction of ReO(PPh3)2Cl3 with tetradentate N2O2-calix[4]arene ligand 8 in ethanol gave the novel mixed-ligand rhenium complex 9 with the structure ReO(N2O2-calix)OEt. The configuration was elucidated by using a number of 1H NMR techniques. In 9, the ethoxy ligand could be easily and quantitatively exchanged for another monodentate ligand to give complex 12. Tetradentate N2S2-calix[4]arene ligand 15 formed the rhenium complex 16 either via reaction with ReO(PPh3)2Cl3 in an organic solvent or by reaction with rhenium gluconate in an aqueous solution. Complex 16 showed good stability in phosphate-buffered saline solution (37 degrees C, 5 d). The crystal structures of a mono- and a bimetallic complex were determined. The bimetallic N2O2-calixarene complex dimer 11 crystallized in the monoclinic space group C2/c, with a = 38.963(5) A, b = 23.140(6) A, c = 27.382(6) A, beta = 128.456(10) degrees, V = 19,333(7) A3, Z = 8, and final R = 0.0519. The monometallic N2S2 model complex 17 crystallized in the monoclinic space group Cc, with a = 15.715(2) A, b = 12.045(2) A, c = 20.022(3) A, beta = 94.863(12) degrees, V = 3776.3(10) A3, Z = 4, and final R = 0.0342.
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Hagen H, Bezemer C, Boersma J, Kooijman H, Lutz M, Spek AL, van Koten G. Vanadium(IV) and -(V) complexes with O,N-chelating aminophenolate and pyridylalkoxide ligands. Inorg Chem 2000; 39:3970-7. [PMID: 11198849 DOI: 10.1021/ic991415s] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two different monoanionic O,N-chelating ligand systems, i.e., [OC6H2(CH2NMe2)-2-Me2-4,6]- (1) and [OCMe2([2]-Py)]- (2), have been applied in the synthesis of vanadium(V) complexes. The tertiary amine functionality in 1 caused reduction of the vanadium nucleus to the 4+ oxidation state with either [VOCl3], [V(=NR)Cl3], or [V(=NR)(NEt2)3] (R = Ph, (3a, 5a), R = p-Tol (3b, 5b)), and applying 1 as a reducing agent resulted in the synthesis of the vanadium(IV) complexes [VO(OC6H2(CH2NMe2)-2-Me2-4,6)2] (4) and [V(=NPh)(OC6H2(CH2NMe2)-2-Me2-4,6)2] (6). In the case of [V(=N-p-Tol)(NEt2)(OC6H2(CH2NMe2)-2-Me2-4,6)2] (7b), the reduction was sufficiently slow to allow its characterization by 1H NMR and variable-temperature studies showed it to be a five-coordinate species in solution. Although the reaction of 1 with [V(=N-p-Tol)(O-i-Pr)3] (9b) did not result in reduction of the vanadium nucleus, vanadium(V) compounds could not be isolated. Mixtures of the vanadium(V) (mono)phenolate, [V(=N-p-Tol)(O-i-Pr)2(OC6H2(CH2NMe2)-2-Me2-4,6)] (10), and the vanadium(V) (bis)phenolate, [V(=N-p-Tol)(O-i-Pr)(OC6H2(CH2NMe2)-2-Me2-4,6)2] (11), were obtained. With the pyridylalkoxide 2, no reduction was observed and the vanadium(V) compounds [VOCl2(OCMe2([2]-Py))] (12) and [V(=N-p-Tol)Cl2(OCMe2([2]-Py)] (13) were obtained. 51V NMR showed 7b and 12 to be five-coordinate in solution, whereas for 10, 11, and 13 a coordination number of 6 was found. Compounds 12 and 13 showed decreased activity compared to their nonchelated vanadium(V) analogues when applied as catalysts in ethene polymerization. Two polymorphic forms with a difference in the V-N-C angle of 12.5 degrees have been found for 6. Crystal data: 6.Et2O, triclinic, P1, a = 11.1557(6) A, b = 12.5744(12) A, c = 13.1051(14) A, alpha = 64.244(8) degrees, beta = 70.472(7) degrees, gamma = 87.950(6) degrees, V = 1547(3) A3, Z = 2; 6.C6H6, triclinic, P1, a = 8.6034(3) A, b = 13.3614(4) A, c = 15.1044(5) A, alpha = 98.182(3) degrees, beta = 105.618(2) degrees, gamma = 107.130(2) degrees, V = 1551.00(10) A3, Z = 2; 12, orthorhombic, Pbca, a = 11.8576(12) A, b = 12.6710(13) A, c = 14.722(2) A, V = 2211.9(4) A3, Z = 8.
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Rohrschneider WK, Hoffend J, Becker K, Clorius JH, Darge K, Kooijman H, Tröger J. Combined static-dynamic MR urography for the simultaneous evaluation of morphology and function in urinary tract obstruction. I. Evaluation of the normal status in an animal model. Pediatr Radiol 2000; 30:511-22. [PMID: 10993535 DOI: 10.1007/s002470000270] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVE A new approach, combined static-dynamic MR urography is evaluated to determine its potential utility for the functional-morphological diagnosis of paediatric urinary tract obstruction. In this initial investigation we sought to evaluate the procedure by imaging the urinary tract of piglets. MATERIALS AND METHODS Twenty-nine healthy piglets were studied with MR urography (MRU), 99mTc-MAG3 diuretic renal scintigraphy (DRS), ultrasound (US) and excretory urography (EU). The functional and morphological findings were compared. For MRU we combined a respiration-triggered 3D-IR-TSE sequence and a dynamic 2D-FFE sequence after Gd-DTPA injection. RESULTS MRU depicted the complete urinary tract with superior image quality compared to EU. Calculation of time-intensity curves from the dynamic sequence permitted determination of single kidney function from parenchymal ROIs and urinary excretion using the whole kidney ROI. MRU and DRS showed significant agreement in the assessment of both single kidney function and urinary excretion. Disturbances of urinary drainage were generally caused by an overfilled bladder. CONCLUSIONS Combined static-dynamic MRU is well suited for the depiction of the complete urinary tract and for the determination of individual kidney function and urinary excretion in the piglet.
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Rohrschneider WK, Becker K, Hoffend J, Clorius JH, Darge K, Kooijman H, Tröger J. Combined static-dynamic MR urography for the simultaneous evaluation of morphology and function in urinary tract obstruction. II. Findings in experimentally induced ureteric stenosis. Pediatr Radiol 2000; 30:523-32. [PMID: 10993536 DOI: 10.1007/s002470000273] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE To assess the diagnostic value of combined static-dynamic MR urography (MRU) for the functional-morphological evaluation of experimentally induced urinary tract obstruction in the piglet. MATERIALS AND METHODS In 20 piglets unilateral ureteric stenosis was created operatively. Post-surgery repeated comparative examinations were obtained with MRU, diuretic renal scintigraphy (DRS), excretory urography (EU) and ultrasound (US). MRU was performed as a combination study with a static 3D-IR-TSE sequence and a dynamic 2D-FFE sequence after Gd-DTPA with frusemide administration. RESULTS MRU allowed complete depiction of the prestenotic urinary tract and of the stenosis in all cases. In 43 comparative studies MRU was superior to EU in 36, EU to MRU in 2. When single kidney function was calculated with both MRU and DRS, results were highly correlated (r = 0.92). When urinary excretion was compared, significant agreement was achieved with concordant findings in 86% and slightly discordant results in 12%. CONCLUSIONS Static-dynamic MR urography permits excellent depiction of experimentally induced urinary tract obstruction in piglets and reliable assessment of individual renal function and urinary excretion. Two advantages of the method stand out--it does not require radiation and it permits functional-morphological correlation.
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Kooijman H, Spek AL. (1 R,4b S,8a R)-(1,2,3,4b,5,6,7,8,8a,9a-Decahydro-4,9a-diazafluoren-1-yl)methanol. Acta Crystallogr C 2000. [DOI: 10.1107/s0108270100007678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
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Velders AH, Kooijman H, Spek AL, Haasnoot JG, de Vos D, Reedijk J. Strong differences in the in vitro cytotoxicity of three isomeric dichlorobis(2-phenylazopyridine)ruthenium(II) complexes. Inorg Chem 2000; 39:2966-7. [PMID: 11196889 DOI: 10.1021/ic000167t] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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172
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Siebenlist R, Frühauf HW, Vrieze K, Kooijman H, Smeets WJJ, Spek AL. Preparation and Properties of Carbonyliron Complexes of 1-Aza-4-oxa-1,3-butadiene (α-Imino Ester). X-ray Crystal Structures of Fe(CO)2(σ(N): σ(C)-i-PrN(H)C(H)C(O)OEt)2 and Fe(CO)2(σ(N): σ(C)-i-PrN(H)C(H)C(O)OMe)(i-PrNC(H)C(O)O). Organometallics 2000. [DOI: 10.1021/om9910266] [Citation(s) in RCA: 10] [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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173
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Siebenlist R, de Beurs M, Feiken N, Frühauf HW, Vrieze K, Kooijman H, Veldman N, Lakin MT, Spek AL. 1,3-Dipolar Cycloaddition to the Fe−XC Fragment 18. Chemoselectivity in the Addition of Activated Alkynes across the Fe−OC Fragment vs the Fe−NC Fragment in Chelate (α-Imino ester)tricarbonyliron Complexes. Organometallics 2000. [DOI: 10.1021/om991027y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
The course of the hydrogenation of [5]- and [6]metacyclophane (1b and 1c) and their thermochemistry is described. Both compounds are hydrogenated rapidly (within 10 s) to furnish the bridgehead olefins 13b and 12c. The accompanying hydrogenation enthalpies are -220 and -141 kJmol(-1), respectively. Strain energies (SE) and olefinic strains (OS) of a number of bridgehead olefins have been evaluated by DFT calculations; it was concluded that 13b belongs to the class of hyperstable olefins which correlates nicely with its reluctance to undergo hydrogenation. By combining experimental hydrogenation enthalpies and DFT calculations, SE of 187 and 121 kJmol(-1) were derived for 1b and 1c.
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van Koningsbruggen PJ, Garcia Y, Kahn O, Fournès L, Kooijman H, Spek AL, Haasnoot JG, Moscovici J, Provost K, Michalowicz A, Renz F, Gütlich P. Synthesis, crystal structure, EXAFS, and magnetic properties of catena [mu-tris(1,2-bis(tetrazol-1-yl)propane-N1,N1')iron(II)] bis(perchlorate). First crystal structure of an iron(II) spin-crossover chain compound. Inorg Chem 2000; 39:1891-900. [PMID: 11428109 DOI: 10.1021/ic991118n] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[Fe(btzp)3](ClO4)2 (btzp = 1,2-bis(tetrazol-1-yl)propane) represents the first structurally characterized Fe(II) linear chain compound exhibiting thermal spin crossover. It shows a very gradual spin transition (T1/2 = 130 K) which has been followed by magnetic susceptibility measurements and 57Fe Mössbauer spectroscopy. The structure has been solved at 200 and 100 K by single-crystal X-ray analysis. It crystallizes in the trigonal space group P3c1 with Z = 2 Fe(II) units at both temperatures. The molecular structure consists of chains running along the c axis in which the Fe(II) ions are linked by three N4,N4' coordinating bis(tetrazole) ligands. The main difference between the two forms appears to be in the Fe-N bond lengths, which are 2.164(4) A at 200 K and 2.038(4) A at 100 K. The Fe-Fe separations are 7.422(1) A at 200 K and 7.273(1) A at 100 K. The EXAFS results are consistent with the crystal structure. In both spin states, the FeN6 octahedron is almost regular within the EXAFS resolution. The Fe-N distance is found as 2.16(2) A at 300 K and 2.00(2) A at 40 K. The absence of the "7 A peak" in the EXAFS spectra of [Fe(btzp)3](ClO4)2, in contrast with what has been observed for the [Fe(4-R-1,2,4-triazole)3]-(anion)2 chain compounds, confirms that this peak can be used as the signature of a metal alignment only when it involves a strongly enhanced multiple scattering M-M-M path, with M-M spacing less than 4 A. Irradiation with green light at 5 K has led to the population of the metastable high-spin state for the iron(II) ion. The nature of the spin-crossover behavior has been discussed on the basis of the structural features.
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