scholarly journals Elements of fractal geometry in the 1H NMR spectrum of a copolymer intercalation-complex: identification of the underlying Cantor set

2018 ◽  
Vol 9 (17) ◽  
pp. 4052-4061 ◽  
Author(s):  
John S. Shaw ◽  
Rajendran Vaiyapuri ◽  
Matthew P. Parker ◽  
Claire A. Murray ◽  
Kate J. C. Lim ◽  
...  

Intercalation of pyrene into the chain-folds of a binary copolyimide results in a self-similar 1H NMR spectrum.

1992 ◽  
Vol 47 (6) ◽  
pp. 755-759 ◽  
Author(s):  
Thomas Kaukorat ◽  
Peter G. Jones ◽  
Reinhard Schmutzler

The 1H NMR spectrum of the spirophosphorane 3 at room temperature indicates dynamic behaviour of the cation. The low-temperature 1H NMR spectra of 3 exhibit two sets of doublets for the protons of the diastereotopic N(CH3)2 groups. The free enthalpy of activation for the dynamic process was determined (58.6 KJ/mole). In the reaction of 3 with sodium tetraphenylborate the crystalline compound, 4, involving the non-coordinating anion, [B(C6H5)4]-, was obtained. The X-ray crystal structure analysis of 4 reveals the presence of a five-membered ring, formally as a result of intramolecular donor-acceptor interaction between the nitrogen atom of the N(CH3)2 group and phosphorus. The geometry at phosphorus deviates somewhat from ideal trigonal bipyramidal.


1980 ◽  
Vol 58 (22) ◽  
pp. 2340-2348 ◽  
Author(s):  
Angel Luis Esteban ◽  
Ernesto Díez

The 1H nmr spectrum of tetrahydrothiophene has been analyzed. The best set of coupling values (Hz) is: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] (A and B refer to α-and β-protons and c and t denote respectively the same and opposite sides of the ring). The variances observed between the values of this set and those reported by Lozach etal., particularly the interchange of the [Formula: see text] and [Formula: see text] couplings, are discussed and it is concluded that our set is the one that reproduces the most fine details of the spectrum profile. The proposed set has been selected as being the most physically meaningful, from amongst 24 equally valid sets of couplings, on the basis of a better agreement with the [Formula: see text] and [Formula: see text] values calculated from a Karplus relationship and from the INDO-FPT method respectively. In these calculations it was assumed that the molecule was interconverting rapidly (on the nmr time scale) between two puckered conformations with C2 symmetry. A detailed discussion of the dependence of the couplings on the height of the pseudorotational barrier and on the temperature indicate that the minimum values of the potential energy correspond to these conformations.


1996 ◽  
Vol 51 (5) ◽  
pp. 691-697 ◽  
Author(s):  
W. Lübbe ◽  
W. Preetz

By reaction of [B6H6]2- with ω,ω′-dibromo-o-xylene in acetonitrile the 1,2-xylylenepentahydro-closo-hexaborat, cis-[B6H5(CH2)2C6H4]- , is formed. The new ansa compound has been separated from excess [B6H6]2- and other reaction products by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structures of cis-[P(C6H5)4][B6H5(CH2)2C6H4] (I) and as-[(n-C4H9)4N][B6H5(CH2)2C6H4] (II) have been determined by single crystal X-ray diffraction analysis: I is monoclinic, space group P 21/n with a = 13.715(5), b = 11.118(1) and c = 19.702(2) Å, β = 103.47(2)°; II is orthorhombic with a = 10.204(7), b = 13.352(4) and c = 20.824(8) Å. The 11B NMR spectrum confirms the structure with a hetero disubstituted octahedral B6 cage with local C2v symmetry. The 13C and 1H NMR spectra have been assigned in term of such a configuration. The IR and Raman spectra exhibit characteristic CH, BH, BC, B6 and arene vibrations.


1992 ◽  
Vol 47 (11) ◽  
pp. 1621-1627 ◽  
Author(s):  
Peter Jeske ◽  
Karl Wieghardt ◽  
Bernhard Nuber

Reaction of LTiCl3 (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) in CH3OH with sodium 2,4-pentanedionate (acac) in the presence of air yields upon addition of NaClO4 yellow crystals of the tetranuclear complex [{LTi(OCH3)}2(μ-O)4{Ti(acac)2}2](ClO4)2·2H2O (1), the crystal structure of which has been determined. Crystal data: monoclinic, P21/c, a = 9.563(4), b = 22.695(8), c = 13.842(5)Å, β = 93.69(3)°; Z = 2. The 400 MHz 1H NMR spectrum shows that two different isomers with Δ, Λ -configuration at the Ti(acac)2(μ-O)2- and (δδδ) or (λλλ) conformation at the LTi(OCH3)(μ-O)2-fragment cocrystallize.


1997 ◽  
Vol 52 (8) ◽  
pp. 939-942 ◽  
Author(s):  
T Koch ◽  
W Preetz

By reaction of (n-Bu4N)2[B12H12] with 4-aminopyridine at 190°C the 4-aminopyridylundecahydro- closo-dodecaborate anion [(4-(NH)-C5H4N)B12H11]- is obtained which can be separated from excess [B12H12]2- by ion exchange chromatography on diethylaminoethyl(DEAE) cellulose. The X-ray structure determination of (Ph4As)[(4-(NH)-C5H4N)B12H11]-2CH3CN (orthorhombic, space group Pbca, a = 14.294(2), b = 19.587(2), c = 27.279(5)Å, Z = 8) reveals that the 4-aminopyridine substituent is bonded via the nitrogen atom of the amino group. The 11B NMR spectrum exhibits the characteristic feature (1:5:5:1) of a monosubstituated B12 cage with a downfield shift of ipso-B1 to -5.4 and antipodal-B12 to -18.1 ppm. The 1H NMR spectrum reveals the pattern of a monosubstituated pyridine. The IR and Raman spectra exhibit characteristic BH stretching vibrations between 2489 and 2521 cm-1 and the CC and CN stretching vibrations in the range of 1405 to 1636 cm-1.


2005 ◽  
Vol 60 (1-2) ◽  
pp. 121-126 ◽  
Author(s):  
B. Louati ◽  
K. Guidara ◽  
M. Gargouri ◽  
M. Fourati

CaHPO4 and SrHPO4 were investigated using Raman, 1H NMR and 31P NMR techniques to study the environment of their PO3−4 tetrahedra and the percentage of mobile protons. 1H NMR spectra at room temperature suggest the presence of three types of protons, in agreement with RX investigation. The percentage of mobile protons in SrHPO4 is greater than in CaHPO4 because Sr2+ is bigger than Ca2+. 31P NMR spectra at room temperature show two lines in the spectrum of SrHPO4, revealing an equal environment of two sets of pairs of PO3− 4 . The 31P NMR spectrum of CaHPO4, however, exhibits three lines. This result was confirmed using a cross polarization (CP) sequence program. The first peak is attributed to the first set of pairs of P(1)O4 units and the two other ones to P(2)O4 and P(2)O4 units.


1997 ◽  
Vol 52 (8) ◽  
pp. 935-938 ◽  
Author(s):  
T Koch ◽  
W Preetz

By reaction of [N(C4H9)4]2[B12H12] with chlorotriphenyltin at 170 °C the phenylundecahydro-closo-dodecaborate anion [(C6H5)B12H11]2- is formed which can be isolated by ion exchange chromatography on diethylaminoethyl(DEAE) cellulose. The crystal structure of [As(C6H5)4]2[(C6H5)B12H11] has been determined by single crystal X-ray diffraction analysis; triclinic, space group P1̄ with a = 11,0066(11), b = 11.1371(6), c = 22.236(2) Å, α = 93.040(6), β = 92.981(8), γ = 100.254(6)°, Z = 2. The 11B NMR spectrum reveals the features (1:5:5:1) of a monosubstituated B12 cage with the ipso B atom at - 6.1 and the antipodal B at -17.4 ppm. The 13C and 1H NMR spectra show the characteristic patterns of the phenyl group. The IR and Raman spectra exhibit characteristic BH stretching vibrations between 2464 and 2519 cm-1 and the CC stretching vibrations in the range of 1405 to 1592 cm-1.


1997 ◽  
Vol 52 (10) ◽  
pp. 1165-1168 ◽  
Author(s):  
T. Koch ◽  
W. Preetz

By reaction of (n-Bu4N)2[B12H12] with 2,2′-bipyridine at 190 °C the 2,2′-bipyridyl-undecahydro- closo-dodecaborate anion [(2,2′-C10H8N2)B12H11]− is formed which can be seperated from excess [B12H12]2− by ion exchange chromatography on diethylaminoethyl (DEAE) cellulose. The X-ray structure determination of (Ph4As)[(2, 2′-C10H8N2)B12H11] (monoclinic, space group P21/c with a = 13.3190(9), b = 10.1532(14), c = 28.788(3′) Å, β = 96.761(7)°, Z = 4) reveals that the bipyridyl substituent is bonded via one nitrogen atom. The 11B NMR spectrum exhibits a 1:5:5:1 pattern with ipso-B1 at -0.3, B2-B6 at -14.5, B7-B11 at -15.3 and antipodal-B12 at -15.9 ppm. The 13C and 1H NMR spectra show the characteristic patterns of the bipyridyl group in the range of 124.5 to 158.6 (13C) and 7.4 to 9.6 ppm (1H) respectively. The IR and Raman spectra exhibit characteristic BH stretching vibrations between 2445 and 2568 cm-1 and the stretching of the CC and CN bonds in the range of 1427 to 1619 cm-1 .


1996 ◽  
Vol 51 (3) ◽  
pp. 363-369 ◽  
Author(s):  
W. Lübbe ◽  
W. Preetz

Abstract By reaction of [B6H6]2- with dibromoethane in acetonitrile μ-dimethylene-bis-hexahydro-closo-hexaborate(2-), [B6H6(CH2)2B6H6]2-, is formed. The compound was separated from excess [B6H6]2- by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structures of [As(C6H5)4]2[B6H6(CH2)2B6H6]·[(CH3)2CO] (I) and [P(C6H5)4]2[B6H6(CH2)2B6H6]·[C2H5OH] (II) have been determined by single crystal X-ray analysis: I is triclinic, space group P1̄ with a = 10.264(2), b = 13.804(2) and c = 20.242(2) Å, α = 97.857(10)°, β = 92.734( 11)° and γ = 103.024( 13)°; II is monoclinic, space group P21/n with a = 12.742(2), b = 7.532(2) and c = 26.887(3) Å, β = 95.765( 10)°. The 11B NMR spectrum of this compound reveals the feature of monosubstituted octahedral B6 cages. The 13C NMR spectrum exhibits a triplet at 16.20 ppm with 1J(C,H) = 120.4 Hz. In the 1H NMR spectrum a singulet at 0.72 ppm of the CH2-groups and two singulets at 1.72 and -4.95 ppm of the BH fragments are observed. The IR and Raman spectra exhibit strong CH stretching bands between 2908 and 2789 cm-1, BH stretching bands between 2463 and 2396 cm-1, and the BC stretching vibration at 1144 in the IR and at 1150 cm-1 in the Raman spectrum.


1994 ◽  
Vol 49 (8) ◽  
pp. 1115-1122 ◽  
Author(s):  
W. Lübbe ◽  
A. Franken ◽  
W. Preetz

By reaction of [B6H6]2- with diiodopropane or diiodobutane in dichloromethane the 1,2- rimethylene-pentahydro-closo-hexaborate(1-), cis-[B6H5(CH2)3]-, and the 1,2-tetra-methylene- entahydro-closo-hexaborate(1-), dv-[B6H5(CH2)4]- are obtained, respectively. The compounds were separated from excess [B6H6]2- by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structures of [P(C6H5)4][B6H5(CH2)3] (I) and [P(C6H5)4][B6H3(CH2)4] (II) have been determined by single crystal X-ray diffraction analy­sis: I is triclinic, space group P1̅ with a = 7,388(2), b = 12,254(2), c = 14,415(2) Å, α = 85,638(12)°, β= 84,06(2)°, γ = 85,13(2)°; II is monoclinic, space group P21/c with a =9,7855(10), b = 11,0793(10), c = 25,2386(10) Å, β= 2,491(10)°. The 11B NMR spectra of oth compounds reveal the feature of a cis-disubstituted octahedral B6 cage. The 13C NMR pectrum of I exhibits a quartet at 15,46 ppm with 1J(C,B) = 121,7 Hz (B-CH2) and a triplet at 37,98 ppm with 1J(C,H) = 124,4 Hz (CH2). For II a quartet at 12,89 ppm with 1J(C,B) = 105,5 Hz (B-CH2) and a triplet at 30,00 ppm with 1J(C,H) = 124,4 Hz (CH2) are observed. In the 1H NMR spectrum of I two multiplets at 0,73 and 1,90 ppm of the CH2 groups and two singlets at 2,23 and -3,71 ppm of the BH fragments are bserved; the signals of the CH2 groups of II are at 0,60 and 1,35 ppm and of the BH fragments at 2,15 and -4,81pm,respectively. The IR and Raman spectra exhibit five very strong CH stretching bands between 2807 and 2938 cm-1 in case of I and between 2817 and 2889 cm 1 in case of II.


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