16 research outputs found
Life on the wall: the diversity and activity of microbes on 13th – century AD. Lan Na mural painting
Diverse microorganisms from the three domains of life (Archaea, Bacteria, and Eukaryota) cause deterioration in mural paintings worldwide; however, few studies have simultaneously targeted these three domains. This study aims to survey the microbiome and its potential for biodeterioration on unpreserved Lan Na mural paintings in Sean Khan temple, Chiang Mai, Thailand. The overview of the archaeal, bacterial, and fungal communities was reported by Illumina sequencing, whereas the potential for deterioration was revealed by culturable techniques and a literature search. The abundant microbes reported in this study were also found in other ancient mural paintings worldwide. Halococcus, a salt-tolerant archaeon, as well as the eubacterial genus Crossiella dominated the prokaryotic community. On the other hand, the main fungal group was the genus Candida (Ascomycota). However, a low number of fungi and bacteria were isolated. Most of the isolates showed the ability to survive in the drought conditions of mural paintings but could not perform discoloration activities. The deterioration activity mainly affected calcium compounds, which are the main components of painting substrates. Aspergillus and several bacterial isolates could dissolve calcium compounds, but only Trichaptum species could induce crystal formation. These results suggest that deterioration of painting substrate should be taken into consideration in addition to deterioration of color in mural paintings. For the Lan Na painting in Sean Khan temple, the plaster is the prime target for biodeterioration, and thus we suggest that the preservation effort should focus on this component of the mural painting
Microwave assisted crystal growth of a new organic-decavanadate assembly: [V10O27(OH)] · 2(C6N2H14) · (C6N2H13) · (C6N2H12) · 2H2O
Microwave synthesis was used to grow single crystals of a new organic-inorganic supramolecular assembly, [V10O27(OH)]·2(C6N2H14)·(C6N2H13)·(C6N2H12)·2H2O, in a very short time compared to the conventional solution technique. In order to generate crystals suitable for single crystal experiments, an equimolar mixture of reactants and a few hours of microwave heating are required. Although non-merohedral twinning is an inherent problem, the crystal structure can be solved and refined in the orthorhombic space group Pna2 (1) with a = 20.972(4) , b = 10.3380(14) , c = 20.432(3) , Z = 4, with an excellent result, R(F2) = 0.0431. The assembly is hydrogen bond-assisted and built up of the monoprotonated decavanadate and 1,4-diazabicyclo[2.2.2]octane of various degrees of protonation. The number and location of protons on both the inorganic and organic motifs govern the formation of the extensive hydrogen bonding network, which in turn regulates the assembly architecture
Base-Directed Formation of Isostructural Lanthanide–Sulfate–Glutarate Coordination Polymers with Photoluminescence
Structural Variation and Preference in Lanthanide-pyridine-2,6-dicarboxylate Coordination Polymers
Ten
lanthanide coordination polymers were designed and synthesized using
pyridine-2,6-dicarboxylic acid (H<sub>2</sub>pdc) and two different
heating techniques (conventional and microwave): [LnÂ(pdc)Â(H<sub>2</sub>O)<sub>4</sub>]<sub>3</sub>·3Cl {<i>Pa</i>3Ě…; Ln = Pr (<b>I</b>), Nd (<b>II</b>), Sm (<b>III</b>), Eu (<b>IV</b>), and Gd (<b>V</b>)}, [LnÂ(pdc)Â(Hpdc)Â(H<sub>2</sub>O)<sub>2</sub>]·3H<sub>2</sub>O {<i>P</i>2<sub>1</sub>/<i>c</i>; Ln = Pr (<b>VI</b>), Nd (<b>VII</b>), and Sm (<b>VIII</b>)} and [LnÂ(pdc)Â(H<sub>2</sub>O)<sub>4</sub>]<sub>3</sub>·3Cl {<i>Ia</i>3Ě…; Ln = Sm (<b>IX</b>), and Eu (<b>X</b>)}. These
complexes show variation in structures depending on the heating technique
and the lanthanide ions. They can be classified into the cubic <i>Pa</i>3̅ (<b>I</b>–<b>V</b>) and <i>Ia</i>3̅ (<b>IX</b>, <b>X</b>), and the monoclinic <i>P</i>2<sub>1</sub>/<i>c</i> (<b>VI</b>–<b>VIII</b>) complexes. The cubic complexes exhibit supramolecular
isomerism and a tubular three-dimensional structure of interpenetrated <b>lcs</b> and <b>pcu</b> net topologies, while the monoclinic
complexes are the supramolecular assemblies of the one-dimensional
chains. As the cubic <i>Pa</i>3Ě… structures are favored
by the use of the microwave, there is variation in structures as conventional
heating was employed, although the cubic <i>Pa</i>3Ě…
structures are still the most favored except for the <b>VI</b> case. The title complexes showed moderate thermal stabilities. The
organic ligand is revealed to be a modest sensitizer to initiate the
photoluminescence in the title complexes
Base-Directed Formation of Isostructural Lanthanide–Sulfate–Glutarate Coordination Polymers with Photoluminescence
A series of five
isostructural 3D lanthanide-based coordination
polymers [LnIII2(H2O)6(glu)(SO4)2]n [Ln
= Pr(1), Nd(2), Sm(3), Eu(4), and Gd(5)] was effortlessly obtained within
a few minutes via the microwave-heating method. The employment of
auxiliary bases, that is, sodium hydroxide, 4,4′-bipyridine,
and 1,4-diazabicyclo[2.2.2]octane, led to the formation of the title
complex, whereas base-free synthesis yielded a three-dimensional inorganic
coordination polymer, [Ln2(H2O)4(SO4)3]n·nH2O, Ln = Nd (2a). The robustness of the
synthetic method was illustrated as both microwave-heating and conventional
hydrothermal techniques also enabled the formation of a high-crystalline
phase-pure complex 1–5. In the structure
of 1–5, glutarato (glu2–) and sulfato ligands link dinuclear Ln(III) building units into
three-dimensional frames. The glu2– ligands act
as tethering linkers, expanding the structure into a neutral 3D coordination
network. Hydrogen bonds were found to be the predominant intermolecular
interactions in the crystal structures. Photoluminescence of the complex 1–5 was studied
Base-Directed Formation of Isostructural Lanthanide–Sulfate–Glutarate Coordination Polymers with Photoluminescence
A series of five
isostructural 3D lanthanide-based coordination
polymers [LnIII2(H2O)6(glu)(SO4)2]n [Ln
= Pr(1), Nd(2), Sm(3), Eu(4), and Gd(5)] was effortlessly obtained within
a few minutes via the microwave-heating method. The employment of
auxiliary bases, that is, sodium hydroxide, 4,4′-bipyridine,
and 1,4-diazabicyclo[2.2.2]octane, led to the formation of the title
complex, whereas base-free synthesis yielded a three-dimensional inorganic
coordination polymer, [Ln2(H2O)4(SO4)3]n·nH2O, Ln = Nd (2a). The robustness of the
synthetic method was illustrated as both microwave-heating and conventional
hydrothermal techniques also enabled the formation of a high-crystalline
phase-pure complex 1–5. In the structure
of 1–5, glutarato (glu2–) and sulfato ligands link dinuclear Ln(III) building units into
three-dimensional frames. The glu2– ligands act
as tethering linkers, expanding the structure into a neutral 3D coordination
network. Hydrogen bonds were found to be the predominant intermolecular
interactions in the crystal structures. Photoluminescence of the complex 1–5 was studied
Base-Directed Formation of Isostructural Lanthanide–Sulfate–Glutarate Coordination Polymers with Photoluminescence
A series of five
isostructural 3D lanthanide-based coordination
polymers [LnIII2(H2O)6(glu)(SO4)2]n [Ln
= Pr(1), Nd(2), Sm(3), Eu(4), and Gd(5)] was effortlessly obtained within
a few minutes via the microwave-heating method. The employment of
auxiliary bases, that is, sodium hydroxide, 4,4′-bipyridine,
and 1,4-diazabicyclo[2.2.2]octane, led to the formation of the title
complex, whereas base-free synthesis yielded a three-dimensional inorganic
coordination polymer, [Ln2(H2O)4(SO4)3]n·nH2O, Ln = Nd (2a). The robustness of the
synthetic method was illustrated as both microwave-heating and conventional
hydrothermal techniques also enabled the formation of a high-crystalline
phase-pure complex 1–5. In the structure
of 1–5, glutarato (glu2–) and sulfato ligands link dinuclear Ln(III) building units into
three-dimensional frames. The glu2– ligands act
as tethering linkers, expanding the structure into a neutral 3D coordination
network. Hydrogen bonds were found to be the predominant intermolecular
interactions in the crystal structures. Photoluminescence of the complex 1–5 was studied
Synergistic Induction of Solvent and Ligand-Substitution in Single-Crystal to Single-Crystal Transformations toward a MOF with Photocatalytic Dye Degradation
External-stimuli
responsiveness as found in natural organisms
and
smart materials is attractive for functional materials scientists
who attempt to design and imitate fascinating behavior into their
materials. Herein, we report a couple of new solvent-responsive isostructural
two-dimensional cationic metal–organic frameworks (MOFs) of
Mn(II) (1a) and Zn(II) (2a) that undergo
unprecedented single-crystal to single-crystal (SCSC) transformation
toward the corresponding isostructural three-dimensional MOFs of Mn(II)
(1b) and Zn(II) (2b). The 2D MOFs 1a and 2a have been effortlessly and rapidly
synthesized via the microwave-heating technique. The SCSC transformations
are synergistically induced by solvent and ligand-substitution reactions
and able to be triggered by water, methanol, ethanol, and n-propanol. Time-dependent SCSC transformations were studied
by in situ X-ray diffraction. Investigations on photodegradation of
methyl orange showed that Zn-MOF 2b has higher efficiency
than Mn-MOF 1b under UV–C irradiation at 300 min,
94.27%, and 21.91%, respectively. The influence of charge on the dye
molecules, heterogeneity of the catalysis, and •OH radical-scavenging test was studied. First-principles computations
suggest that the high photocatalytic activity of 2b may
be attributed to its suitable band-edge position for redox reactions
Synergistic Induction of Solvent and Ligand-Substitution in Single-Crystal to Single-Crystal Transformations toward a MOF with Photocatalytic Dye Degradation
External-stimuli
responsiveness as found in natural organisms
and
smart materials is attractive for functional materials scientists
who attempt to design and imitate fascinating behavior into their
materials. Herein, we report a couple of new solvent-responsive isostructural
two-dimensional cationic metal–organic frameworks (MOFs) of
Mn(II) (1a) and Zn(II) (2a) that undergo
unprecedented single-crystal to single-crystal (SCSC) transformation
toward the corresponding isostructural three-dimensional MOFs of Mn(II)
(1b) and Zn(II) (2b). The 2D MOFs 1a and 2a have been effortlessly and rapidly
synthesized via the microwave-heating technique. The SCSC transformations
are synergistically induced by solvent and ligand-substitution reactions
and able to be triggered by water, methanol, ethanol, and n-propanol. Time-dependent SCSC transformations were studied
by in situ X-ray diffraction. Investigations on photodegradation of
methyl orange showed that Zn-MOF 2b has higher efficiency
than Mn-MOF 1b under UV–C irradiation at 300 min,
94.27%, and 21.91%, respectively. The influence of charge on the dye
molecules, heterogeneity of the catalysis, and •OH radical-scavenging test was studied. First-principles computations
suggest that the high photocatalytic activity of 2b may
be attributed to its suitable band-edge position for redox reactions
Ligand-Substitution-Induced Single-Crystal to Single-Crystal Transformations in a Redox-Versatile Cu(II) MOF toward Smartphone-Based Colorimetric Detection of Iodide
Fabrication
of a new three-dimensional Cu(II) metal–organic
framework, {[Cu4(4,4′-bipy)3(OH)2(mal)3]·4H2O}n (1a; 4,4′-bipy = 4,4′-bipyridine,
H2mal = malonic acid; P21/m), that undergoes an unprecedented redox-versatile ligand-substitution-induced
single-crystal to single-crystal transformation, for smartphone-based
detection of iodide was studied. The Cu-MOF 1a has been
effortlessly synthesized by the microwave-heating technique. Phase
formation of the Cu-MOF 1a depended on counter-anions.
The transformations can be triggered by halides to corresponding coordination
polymers through both non-redox and redox-associated pathways. The
changes in the local structure and oxidation state of copper during
the transformation were studied by ex situ and in situ synchrotron
X-ray absorption spectroscopies. The selectivity of the halide-triggered
transformation was investigated. A study on smartphone-based colorimetric
detection of iodide was found to be linearly proportional to the iodide
concentration in the range 10–1500 mg/L with a limit of detection
of 5 mg/L and good precision relative standard deviation of 1.9% (n = 11), possibly to construct the iodide test kit