Cheol Joo Moon

Self-Assembled Tb3+ Complex Probe for Quantitative Analysis of ATP during Its Enzymatic Hydrolysis via Time-Resolved Luminescence in Vitro and in Vivo

To more accurately assess the pathways of biological systems, a probe is needed that may respond selectively to adenosine triphosphate (ATP) for both in vitro and in vivo detection modes. We have developed a luminescence probe that can provide real-time information on the extent of ATP, ADP, and AMP by virtue of the luminescence and luminescence lifetime observed from a supramolecular polymer based on a C3 symmetrical terpyridine complex with Tb3+ (S1-Tb). The probe shows remarkable selective luminescence enhancement in the presence of ATP compared to other phosphate-displaying nucleotides including adenosine diphosphate (ADP), adenosine monophosphate (AMP), guanosine triphosphate (GTP), thymidine triphosphate (TTP), H2PO4- (Pi), and pyrophosphate (PPi). In addition, the time-resolved luminescence lifetime and luminescence spectrum of S1-Tb could facilitate the quantitative measurement of the exact amount of ATP and similarly ADP and AMP within living cells. The time-resolved luminescence lifetime of S1-Tb could also be used to quantitatively monitor the amount of ATP, ADP, and AMP in vitro following the enzymatic hydrolysis of ATP. The long luminescence lifetime, which was observed into the millisecond range, makes this S1-Tb-based probe particularly attractive for monitoring biological ATP levels in vivo, because any short lifetime background fluorescence arising from the complex molecular environment may be easily eliminated.

Origin of Both Right- and Left-Handed Helicities in a Supramolecular Gel with and without Ni2+ at the Supramolecular Level

We demonstrate the different origins of helical directions in polymeric gels derived from a hydrazone reaction in the absence and presence of Ni2+. The right-handed helicity of polymeric gels without Ni2+ originates from the enantiomeric d-form alanine moiety embedded in the building block. However, the right-handed helicity is inverted to a left-handed helicity upon the addition of Ni2+, indicating that added Ni2+ greatly affects the conformation of the polymeric gel by overcoming the influence of the enantiomer embedded in the building block on the helicity at the supramolecular level. More interestingly, the ratio of the right-toleft-handed helical fibers varies with the concentration of Ni2+, which converts from 100% right-handed helical fiber to 90% left-handed helical fiber. In the presence of Ni2+, both right- and left-handed helical fibers coexist at the supramolecular level. Some fibers also exhibit both right- and left-handed helicities in a single fiber.

Isomer-Specific Induced Circular Dichroism Spectroscopy of Jet-Cooled Phenol Complexes with (−)-Methyl l-Lactate

Induced circular dichroism (ICD) is the CD observed in the absorption of an achiral molecule bound to a transparent chiral molecule through noncovalent interactions. ICD spectroscopy has been used to probe the binding between molecules, such as protein-ligand interactions. However, most ICD spectra have been measured in solution, which only exhibit the averaged CD values of all conformational isomers in solution. Here, we obtained the first isomer-selective ICD spectra by applying resonant two-photon ionization CD spectroscopy to jet-cooled phenol complexes with (-)-methyl l-lactate (PhOH-(-)ML). The well-resolved CD bands in the spectra were assigned to two conformers, which contained different types of hydrogen-bonding interactions between PhOH and (-)ML. The ICD values of the two conformers have different signs and magnitudes, which were explained by differences both in the geometrical asymmetries of PhOH bound to (-)ML and in the electronic coupling strengths between PhOH and (-)ML.

Photodissociation kinetics of the isobutanal radical cation: a combined experimental and theoretical study

The competitive photodissociation kinetics of the isobutanal radical cation ((CH3)2CHCHO+˙, 1) were investigated using experimental and theoretical methods. The photodissociation was followed by the 2 + 1 REMPI process in the gas phase. The reaction pathways for the main product ions with m/z 43 and 29 were determined by calculating the potential energy surface of the dissociation with the G4 method. Through a kinetic analysis using RRKM calculations, we proposed that the main photodissociation pathways were 1 → (CH3)2CH+ + CHO˙, 1 → (CH3)2CH+ + H˙ + CO, and 1 → CH3CH2COCH3+˙ → CH3CH2+ + CH3˙ + CO.

Crystal structure of N,N′-di­decyl­pyromellitic di­imide

The title compound comprises a central pyromellitic diimide moiety with terminal decyl groups, with potential applications as an acaricide, insecticide and mematicide.

Crystal structure of N-[2-(cyclo­hexyl­sulfan­yl)eth­yl]quinolinic acid imide

In the crystal of the title compound, C—H⋯O hydrogen bonds and C—O⋯π interactions form a two-dimensional network lying parallel to the ab plane.