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  1. Arman HD, Tiekink ER
    PMID: 24427074 DOI: 10.1107/S160053681302271X
    The asymmetric unit of title co-crystal, C10H8N2·2C7H7NO2, comprises a centrosymmetric 4,4'-bi-pyridine mol-ecule, and a 2-amino-benzoic acid mol-ecule in a general position. The latter is effectively planar [C-C-C-O torsion angle = 5.0 (3)°] owing to an intra-molecular N-H⋯O(carbon-yl) hydrogen bond. Three-mol-ecule aggregates are formed via O-H⋯N(pyrid-yl) hydrogen bonds and these are connected into supra-molecular layers in the bc plane by N-H⋯O(carbon-yl) hydrogen bonds and π-π inter-actions between pyridyl and benzene rings [inter-centroid distance = 3.634 (2) Å]. Layers are connected along the a axis by weak π-π inter-actions between benzene rings [3.964 (2) Å].
  2. Arman HD, Tiekink ER
    PMID: 24427071 DOI: 10.1107/S1600536813022563
    The asymmetric unit of the title co-crystal, C10H6O8·2C8H10N4O2, comprises a centrosymmetric benzene-1,2,4,5-tetra-carb-oxy-lic acid (LH4) mol-ecule and a mol-ecule of caffeine in a general position. LH4 is nonplanar, with the dihedral angles between the ring and pendent carb-oxy-lic acid groups being 44.22 (7) and 49.74 (7)°. By contrast, the caffeine mol-ecule is planar (r.m.s. deviation = 0.040 Å). Supra-molecular layers parallel to (-1-10) are sustained by carb-oxy-lic acid O-H⋯O(carbon-yl) and O-H⋯N(imidazole) hydrogen bonds, as well as by meth-yl-carbonyl C-H⋯O inter-actions. These stack via π-π inter-actions between the benzene and imidazole rings [inter-centroid distance = 3.4503 (10) Å].
  3. Arman HD, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2013 Oct 5;69(Pt 11):o1616.
    PMID: 24454067 DOI: 10.1107/S1600536813027128
    The asymmetric unit of the title co-crystal, C12H12N2·2C7H7NO2, comprises a centrosymmetric 4-[2-(pyridin-4-yl)eth-yl]pyridine mol-ecule and a 2-amino-benzoic acid mol-ecule in a general position. The acid has a small twist between the carb-oxy-lic acid residue and the ring [dihedral angle = 7.13 (6)°] despite the presence of an intra-molecular N-H⋯O(carbon-yl) hydrogen bond. Three-mol-ecule aggregates are formed via O-H⋯N(pyrid-yl) hydrogen bonds, and these are connected into supra-molecular layers in the bc plane by N-H⋯O(carbon-yl) hydrogen bonds and π-π inter-actions between pyridine and benzene rings [inter-centroid distance = 3.6332 (9) Å]. Layers are connected along the a axis by weak π-π inter-actions between benzene rings [3.9577 (10) Å].
  4. Arman HD, Kaulgud T, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Apr 1;70(Pt 4):o402-3.
    PMID: 24826120 DOI: 10.1107/S1600536814004838
    The sulfa-thia-zole mol-ecule in the title 1:1 co-crystal, C9H9N3O2S2·C18H12N6, adopts an approximate L-shape [dihedral angle between the five- and six-membered rings = 86.20 (9)°] and features an intra-molecular hypervalent S⋯O inter-action [2.8666 (15) Å]. Overall, the triazine mol-ecule has the shape of a disk as the pendant pyridine rings are relatively close to coplanar with the central ring [dihedral angles = 18.35 (9), 6.12 (9) and 4.67 (9)°]. In the crystal packing, a linear supra-molecular chain aligned along [01-1] is formed as a result of amino-pyridyl N-H⋯N hydrogen bonding with syn-disposed pyridyl mol-ecules of one triazine, and amine-pyridyl N-H⋯N hydrogen bonding with the third pydridyl ring of a second triazine mol-ecule. A three-dimensional architecture arises as the chains are connected by C-H⋯O inter-actions.
  5. Arman HD, Kaulgud T, Tiekink ER
    PMID: 24427073 DOI: 10.1107/S1600536813022691
    The asymmetric unit of the title co-crystal, 2C14H13N2 (+)·C10H4O8 (2-)·2C14H12N2·C10H6O8, comprises a 2,9-dimethyl-1,10-phenanthrolin-1-ium cation (Me2PhenH(+)) and a 2,9-dimethyl-1,10-phenanthroline mol-ecule (Me2Phen), each in a general position, and half each of a 2,5-di-carb-oxy-benzene-1,4-di-carboxyl-ate dianion (LH2 (2-)) and a benzene-1,2,4,5-tetra-carb-oxy-lic acid mol-ecule (LH4), each being disposed about a centre of inversion. Small twists are evident in the dianion [the C-C-C-O torsion angles are 168.41 (18) and 16.2 (3)°], whereas a major twist is found for one carb-oxy-lic acid group in the neutral mol-ecule [C-C-C-O = 66.3 (2) and 18.2 (3)°]. The most prominent feature of the crystal packing is the formation of linear supra-molecular chains along [001] mediated by charge-assisted O-H⋯O(-) hydrogen bonding between alternating LH4 and LH2 (2-). These are connected to the Me2PhenH(+) and Me2Phen species by N-H⋯O and O-H⋯N hydrogen bonds, respectively. A three-dimensional architecture is formed by C-H⋯O and π-π inter-actions [inter-centroid distance = 3.5337 (17) Å].
  6. Arman HD, Kaulgud T, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2013 Oct 5;69(Pt 11):o1615.
    PMID: 24454066 DOI: 10.1107/S1600536813027037
    The asymmetric unit of the title co-crystal, C12H14N4O2S·0.5C6H12N2, comprises the sulfonamide mol-ecule and half a mol-ecule of 1,4-di-aza-bicyclo-[2.2.2]octane (DABCO), the latter being disposed about a crystallographic twofold rotation axis. In the sulfonamide mol-ecule, the aromatic rings are almost perpendicular to one another [dihedral angle = 75.01 (8)°]. In the crystal, mol-ecules are connected into a three-mol-ecule aggregate via amide-DABCO N-H⋯N hydrogen bonds, and these are connected into a three-dimensional architecture via amino-DABCO N-H⋯O and amino-pyrimidine N-H⋯N hydrogen bonds.
  7. Arman HD, Miller T, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2013 Oct 2;69(Pt 11):o1606.
    PMID: 24454058 DOI: 10.1107/S1600536813026810
    The asymmetric unit of the title salt, C12H14N2 (2+)·2C7H3N2O6 (-), comprises half a 4-[2-(pyridin-1-ium-4-yl)eth-yl]pyridin-1-ium dication, being disposed about a centre of inversion, and a 2,6-di-nitro-benzoate anion, in a general position. In the anion, the carboxyl-ate group is inclined to the benzene ring [dihedral angle = 85.45 (9)°], whereas near-coplanar and twisted arrangements are found for the nitro groups [O-N-C-C torsion angles = 179.80 (14) and 20.2 (2)°]. In the crystal, three-component aggregates sustained by charge-assisted N(+)-H⋯O(-) hydrogen bonds are found and these are consolidated into a three-dimensional architecture by C-H⋯O and π-π [inter-centroid distances = 3.6796 (14) and 3.7064 (14) Å] inter-actions.
  8. Arman HD, Poplaukhin P, Tiekink ER
    PMID: 24426981 DOI: 10.1107/S1600536813021569
    The asymmetric unit of title salt co-crystal, [K(C9H11N2S2)(C12H24O6)], comprises a K(+) cation, an (-)S2CN(Et)py anion and a 18-crown-6 mol-ecule. Substantial delocalization of π-electron density is evident in the di-thio-carbamate anion, as indicated by the equivalent C-S bond lengths. The K(+) cation sits within an O6S2 donor set lying 0.7506 (6) Å out of the least-squares plane through the six O atoms (r.m.s. deviation = 0.1766 Å) of the 18-crown-6 mol-ecule with the two S atoms being on one side of this plane. Supra-molecular layers in the bc plane, sustained by C-H⋯O and C-H⋯π inter-actions, feature in the crystal packing.
  9. Poplaukhin P, Arman HD, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2017 Jul 01;73(Pt 8):1162-1166.
    PMID: 28932428 DOI: 10.1107/S2056989017010179
    The title compound, {[Zn(C9H11N2S2)2]·0.5C6H7N} n , comprises two independent, but chemically similar, Zn[S2CN(Et)CH2py]2 residues and a 4-methyl-pyridine solvent mol-ecule in the asymmetric unit. The Zn-containing units are connected into a one-dimensional coordination polymer (zigzag topology) propagating in the [010] direction, with one di-thio-carbamate ligand bridging in a μ2-κ(3) mode, employing one pyridyl N and both di-thio-carbamate S atoms, while the other is κ(2)-chelating. In each case, the resultant ZnNS4 coordination geometry approximates a square pyramid, with the pyridyl N atom in the apical position. In the crystal, the chains are linked into a three-dimensional architecture by methyl- and pyridyl-C-H⋯S, methyl-ene-C-H⋯N(pyrid-yl) and pyridyl-C-H⋯π(ZnS2C) inter-actions. The connection between the chain and the 4-methyl-pyridine solvent mol-ecule is of the type pyridyl-C-H⋯N(4-methyl-pyridine).
  10. Arman HD, Poplaukhin P, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2017 Oct 01;73(Pt 10):1501-1507.
    PMID: 29250367 DOI: 10.1107/S2056989017012956
    The title structures, [Zn2(C3H6NS2)4(C14H14N4O2)]·2C3H7NO (I) and [Zn2(C7H14NS2)4(C14H14N4O2)] (II), each feature a bidentate, bridging bipyridyl-type ligand encompassing a di-amide group. In (I), the binuclear compound is disposed about a centre of inversion, leading to an open conformation, while in (II), the complete mol-ecule is completed by the application of a twofold axis of symmetry so that the bridging ligand has a U-shape. In each of (I) and (II), the di-thio-carbamate ligands are chelating with varying degrees of symmetry, so the zinc atom is within an NS4 set approximating a square-pyramid for (I) and a trigonal-bipyramid for (II). The solvent di-methyl-formaide (DMF) mol-ecules in (I) connect to the bridging ligand via amide-N-H⋯O(DMF) and various amide-, DMF-C-H⋯O(amide, DMF) inter-actions. The resultant three-mol-ecule aggregates assemble into a three-dimensional architecture via C-H⋯π(pyridyl, chelate ring) inter-actions. In (II), undulating tapes sustained by amide-N-H⋯O(amide) hydrogen bonding lead to linear supra-molecular chains with alternating mol-ecules lying to either side of the tape; no further directional inter-actions are noted in the crystal.
  11. Arman HD, Poplaukhin P, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2017 Apr 01;73(Pt 4):488-492.
    PMID: 28435704 DOI: 10.1107/S2056989017003516
    The title compound, {[Cd(C9H11N2S2)2]·C6H7N} n , features two μ2-κ3-di-thio-carbamate ligands each of which chelates one CdII atom, via the S atoms, while simultaneously bridging to another via the pyridyl-N atom. The result is a two-dimensional coordination polymer extending parallel to the ab plane with square channels along the b axis. The CdII atom geometry is based on a distorted cis-N2S4 octa-hedron. The 3-methyl-pyridine mol-ecules reside in the channels aligned along the b axis, being held in place by methyl-ene-C-H⋯N(3-methyl-pyridine) and (3-methyl-pyridine)-C-H⋯π(pyrid-yl) inter-actions. Pyridyl-C-H⋯S and di-thio-carbamate-methyl-C-H⋯π(pyrid-yl) inter-actions provide connections between layers along the c axis.
  12. Jotani MM, Poplaukhin P, Arman HD, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Aug 01;72(Pt 8):1085-92.
    PMID: 27536388 DOI: 10.1107/S2056989016010768
    The asymmetric unit of the title compound, [Cd2(C12H10N2)3(C6H12NOS2)4]·4C2H3N, comprises a Cd(II) atom, two di-thio-carbamate (dtc) anions, one and a half trans-1,2-dipyridin-4-yl-ethyl-ene (bpe) mol-ecules and two aceto-nitrile solvent mol-ecules. The full binuclear complex is generated by the application of a centre of inversion. The dtc ligands are chelating, one bpe mol-ecule coordinates in a monodentate mode while the other is bidentate bridging. The resulting cis-N2S4 coordination geometry is based on an octa-hedron. Supra-molecular layers, sustained by hy-droxy-O-H⋯O(hy-droxy) and hy-droxy-O-H⋯N(bpe) hydrogen bonding, inter-penetrate to form a three-dimensional architecture; voids in this arrangement are occupied by the aceto-nitrile solvent mol-ecules. Additional inter-molecular inter-actions falling within the specified framework have been analysed by Hirshfeld surface analysis, including π-π inter-actions.
  13. Jotani MM, Arman HD, Poplaukhin P, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Dec 01;72(Pt 12):1700-1709.
    PMID: 27980812
    The common feature of the mol-ecular structures of the title compounds, [Zn(C5H10NS2)2(C5H5NO)], (I), and [Zn(C4H8NOS2)2(C5H5NO)], (II), are NS4 donor sets derived from N-bound hy-droxy-pyridyl ligands and asymmetrically chelating di-thio-carbamate ligands. The resulting coordination geometries are highly distorted, being inter-mediate between square pyramidal and trigonal bipyramidal for both independent mol-ecules comprising the asymmetric unit of (I), and significantly closer towards square pyramidal in (II). The key feature of the mol-ecular packing in (I) is the formation of centrosymmetric, dimeric aggregates sustained by pairs of hy-droxy-O-H⋯S(di-thio-carbamate) hydrogen bonds. The aggregates are connected into a three-dimensional architecture by methyl-ene-C-H⋯O(hy-droxy) and methyl-C-H⋯π(chelate) inter-actions. With greater hydrogen-bonding potential, supra-molecular chains along the c axis are formed in the crystal of (II), sustained by hy-droxy-O-H⋯O(hy-droxy) hydrogen bonds, with ethyl-hydroxy and pyridyl-hydroxy groups as the donors, along with ethyl-hydroxy-O-H⋯S(di-thio-carbamate) hydrogen bonds. Chains are connected into layers in the ac plane by methyl-ene-C-H⋯π(chelate) inter-actions and these stack along the b axis, with no directional inter-actions between them. An analysis of the Hirshfeld surfaces clearly distinguished the independent mol-ecules of (I) and reveals the importance of the C-H⋯π(chelate) inter-actions in the packing of both (I) and (II).
  14. Abdul Hadi D, Mansharan Kaur CS, Effat O, Siew SF
    Trop Biomed, 2019 Dec 01;36(4):850-854.
    PMID: 33597457
    Tuberculosis (TB) is a highly infectious disease on the rise caused by the organism Mycobacterium tuberculosis and health care workers working in emergency departments, medical wards and autopsy rooms are in danger of contacting this disease. We present a case of a 42 year old man found dead under a pedestrian bridge with no medical history available. Post mortem computed tomography showed multiple cavities involving upper lobes of both lungs and areas of consolidation in both lung fields raising the suspicion of pulmonary tuberculosis. This was followed by a computed tomography guided lung biopsy and a limited conventional autopsy done in situ in a special high risk autopsy suite with appropriate ventilation. This case highlights the importance of cross sectional imaging which can be coupled with image guided biopsy in cases of infectious disease to reduce the risk of transmission to health care workers.
  15. Ong TL, Lau YH, Ngu LH, Hadi D, Lau KM, Mawardi AS
    Mov Disord Clin Pract, 2023 Aug;10(Suppl 3):S38-S40.
    PMID: 37636236 DOI: 10.1002/mdc3.13780
  16. Anuar MA, Lee JX, Musa H, Abd Hadi D, Majawit E, Anandakrishnan P, et al.
    Brain Dev, 2023 Nov;45(10):547-553.
    PMID: 37661525 DOI: 10.1016/j.braindev.2023.06.004
    INTRODUCTION: Since the emergence of COVID-19, we have experienced potent variants and sub-variants of the virus with non-specific neurological manifestations. We observed a surge of the Omicron variant of COVID-19 patients with neurological manifestations where less cases of multisystem inflammatory syndrome in children (MIS-C) were reported. This article describes our experience of children with severe and rare neurological manifestations following COVID-19 infection.

    METHODS: This is a retrospective observational case series of patients under 18 years old who fulfilled the WHO COVID-19 case definition and were referred to our paediatric neurology unit at Hospital Tunku Azizah Kuala Lumpur. Their demographic data, neurological symptoms, laboratory and supporting investigations, neuroimaging, treatment and outcomes were collected and analysed.

    RESULTS: There were eleven patients with neurological manifestations who fulfilled the WHO COVID-19 case definition. Nine patients presented with seizures and/or encephalopathy, one patient with eye opsoclonus and another patient with persistent limbs myokymia. Based on the history, clinical, electrophysiological and radiological findings, two of them had febrile infection-related epilepsy syndrome, two had acute disseminated encephalomyelitis, two had acute necrotising encephalopathy of childhood, one each had hemiconvulsion-hemiplegia-epilepsy syndrome, acute encephalopathy with bilateral striatal necrosis, hemi-acute encephalopathy with biphasic seizures and reduced diffusion, infection-associated opsoclonus and myokymia.

    CONCLUSIONS: This case series highlighted a wide spectrum of neurological manifestations of COVID-19 infection. Early recognition and prompt investigations are important to provide appropriate interventions. It is essential that these investigations should take place in a timely fashion and COVID-19 quarantine period should not hinder the confirmation of various presenting clinical syndromes.

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