0000000001298908
AUTHOR
Judith A. K. Howard
showing 28 related works from this author
Interplay between spin crossover and proton migration along short strong hydrogen bonds
2021
The iron(ii) salt [Fe(bpp)2](isonicNO)2·HisonicNO·5H2O (1) (bpp = 2,6-bis(pyrazol-3-yl)pyridine; isonicNO = isonicotinate N-oxide anion) undergoes a partial spin crossover (SCO) with symmetry breaking at T1 = 167 K to a mixed-spin phase (50% high-spin (HS), 50% low-spin (LS)) that is metastable below T2 = 116 K. Annealing the compound at lower temperatures results in a 100% LS phase that differs from the initial HS phase in the formation of a hydrogen bond (HB) between two water molecules (O4W and O5W) of crystallisation. Neutron crystallography experiments have also evidenced a proton displacement inside a short strong hydrogen bond (SSHB) between two isonicNO anions. Both phenomena can al…
Experimental and theoretical studies into the structural perturbations between neutral, oxidised and reduced forms of 1,4-dithiinoquinoxaline derivat…
2000
The syntheses and electrochemistry of thieno[3',4'r5,6][1,4]dithiino[2,3-b]quinoxaline (9), 2,3-bis(methylsulfanyl)[1,4]dithiino[2,3-b]quinoxaline (16) and 2,3-ethylenedisulfanyl[1,4]dithiino[2,3-b]quinoxaline (17) are reported, together with the X-ray crystal structures of 9, 16 and the charge-transfer complex 9.TCNQ. In the thieno derivative 9, the molecular structure undergoes a significant change from a boat conformer to a planar system, upon oxidation with TCNQ. Theoretical calculations show that oxidation leads to planarisation of the molecular structure due to the aromatisation of the dithiine moiety. The study of the oxidised/reduced species helps to rationalise the electrochemical …
Donor-π-Acceptor Species Derived from Functionalised 1,3-Dithiol-2-ylidene Anthracene Donor Units Exhibiting Photoinduced Electron Transfer Propertie…
1998
Steric interactions between the anthraquinoid core and the 1,3-dithiole and dicyanomethylene groups play a key role in determining the physical properties of system 1. The intramolecular charge transfer properties of this donor–π-acceptor species have been explored and cyclic voltammetric data, X-ray crystal structures and ab initio calculations are also reported.
Sulfur, tin and gold derivatives of 1-(2'-pyridyl)-ortho-carborane, 1-R-2-X-1,2-C2B10H10 (R = 2'-pyridyl, X = SH, SnMe3 or AuPPh3).
2004
Reaction of the lithium salt of 1-(2'-pyridyl)-ortho-carborane, Li[1-R-1,2-C(2)B(10)H(10)](R = 2'-NC(5)H(4)), with sulfur, followed by hydrolysis, gave the mercapto-o-carborane, 1-R-2-SH-1,2-C(2)B(10)H(10) which forms chiral crystals containing helical chains of molecules linked by intermolecular S-H...N hydrogen bonds. The cage C(1)-C(2) and exo C(2)-S bond lengths (1.730(3) and 1.775(2)[Angstrom], respectively) are indicative of exo S=C pi bonding. The tin derivative 1-R-2-SnMe(3)-1,2-C(2)B(10)H(10), prepared from Li[1-R-1,2-C(2)B(10)H(10)] and Me(3)SnCl, crystallises with no significant intermolecular interactions. The pyridyl group lies in the C(1)-C(2)-Sn plane, oriented to minimise th…
A reversible hydrogen‐bond isomerization triggered by an abrupt spin crossover near room temperature.
2020
The spin crossover salt [Fe(bpp) 2 ](isonicNO) 2 ·2.4H 2 O ( 1 ·2.4H 2 O) (bpp = 2,6‐bis(pyrazol‐3‐yl)pyridine; isonicNO = isonicotinate N‐oxide anion) exhibits a very abrupt spin crossover at T 1 /2 = 274.4 K. This triggers a supramolecular linkage (H‐bond) isomerization that responds reversibly towards light irradiation or temperature change. Isotopic effects in the thermomagnetic behaviour reveal the importance of hydrogen bonds in defining the magnetic state. Further, the title compound can be reversibly dehydrated to afford 1 , a material that also exhibits spin crossover coupled to H‐bond isomerization, leading to strong kinetic effects in the thermomagnetic properties.
Synthesis, crystal structure, magnetic properties and 57Fe Mossbauer spectroscopy of the new trinuclear [Fe3(4-(2'-hydroxyethyl)-1,2,4- triazole)6(H2…
2000
Hyetrz = 4-(2prime-hydroxyethyl)-1,2,4-triazole represents the first structurally characterized iron(II) spin crossover compound for which the structure has been solved above and below room temperature in both spin states. The compound crystallizes in the trigonal system, space group R3, a = 12.763(1) b= 67.144(1), V = 1684.3(1) 3, Z = 6 at 120K. At 330K the space group is retained and a = 13.0183(3) b=67.376(3), V = 1805.8(1) 3. The molecular structure consists of trinuclear FeII entities linked together by an unprecedented three-dimensional network of hydrogen bonds. This compound shows a gradual spin crossover behavior centered around room temperature, which has been followed by temperat…
CCDC 1984964: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B
CCDC 1984962: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B
CCDC 1973926: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2020|Chem.-Eur.J.|27|740|doi:10.1002/chem.202003654
CCDC 1973938: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2020|Chem.-Eur.J.|27|740|doi:10.1002/chem.202003654
CCDC 1984958: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B
CCDC 2013419: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2020|Chem.-Eur.J.|27|740|doi:10.1002/chem.202003654
CCDC 1973924: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2020|Chem.-Eur.J.|27|740|doi:10.1002/chem.202003654
CCDC 1973940: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2020|Chem.-Eur.J.|27|740|doi:10.1002/chem.202003654
CCDC 1984961: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B
CCDC 1973936: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2020|Chem.-Eur.J.|27|740|doi:10.1002/chem.202003654
CCDC 1832988: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B
CCDC 1973941: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2020|Chem.-Eur.J.|27|740|doi:10.1002/chem.202003654
CCDC 1984957: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B
CCDC 1974500: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2020|Chem.-Eur.J.|27|740|doi:10.1002/chem.202003654
CCDC 1832962: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B
CCDC 1984960: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B
CCDC 1973928: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2020|Chem.-Eur.J.|27|740|doi:10.1002/chem.202003654
CCDC 1984963: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B
CCDC 1973929: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2020|Chem.-Eur.J.|27|740|doi:10.1002/chem.202003654
CCDC 1984959: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B
CCDC 1873604: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B
CCDC 1873602: Experimental Crystal Structure Determination
2020
Related Article: Verónica Jornet-Mollá, Carlos Giménez-Saiz, Laura Cañadillas-Delgado, Dmitry S. Yufit, Judith A. K. Howard, Francisco M. Romero|2021|Chemical Science|12|1038|doi:10.1039/D0SC04918B