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The 1,4-dihydronicotinamide adenine dinucleotide (NADH) is one of the key coenzymes that participates in various metabolic processes including maintaining the redox balance. Early information on the imbalance of NADH is crucial in the context of diagnosing the pathogenic conditions. Thus, a dual-channel fluorescent probe (MQN) is developed for tracking of NADH/NAD­(P)H in live cells. In the presence of NADH, only it showed emission signals at 460 and 550 nm upon excitation at 390 and 450 nm, respectively. The probe could provide accurate information on NADH levels in cancer cells (HeLa) and normal cells (WI-38). We observed that the NADH level in cancer cells (HeLa) is relatively higher than that in normal WI-38 cells. We received similar information on NADH upon calibrating with a commercial NADH kit. Moreover, we evaluated substrate-specific NADH expression in the glycolysis pathway and oxidative phosphorylation process. Also, the dual-channel probe MQN has visualized NADH manipulation in the course of depletion of GSH to maintain cellular redox balance. This dual-channel molecular probe MQN comes out as a new detection tool for NADH levels in live cells and tumor mimic spheroids.

Herein we report a facile transformation of hydroxylated cucurbit[n]uril (CB[n], n = 6 and 7) to other functionality-conjugated CB[n]s by nucleophilic substitution of the hydroxyl group with a wide range of nitriles and alcohols. The reaction proceeds efficiently via generation of a superelectrophilic carbocation on the CB framework from hydroxylated CB[n]s under superacidic conditions. One of the resulting CB[n] derivatives with reactive functionality, monocarboxylated CB[7], is efficiently conjugated to an enzyme (horseradish peroxidase, HRP) by amide coupling. This provides a CB[7]conjugated functional biomaterial (CB[7]-HRP) that selectively detects proteins labeled with a guest, adamantylammonium (AdA), based on bioorthogonal high-affinity host−guest interactions between CB[7] and AdA. We demonstrated the potential of overcoming the limitations in preparing reactive functional CB[n] derivatives, enabling the exploration of novel bioapplications of CB[n]-based host−guest chemistry with new CB[n]-conjugated functional materials.

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Four new chiral tweezer-diamine complexes, consisting of an achiral ferrocene-bridged Zn(II)bisporhyrin host (1) and two small diamines (1R,2R)-1,2-diphenylethylene diamine {(1R,2R)-DPEA} and (1S,2S)-1,2-cyclohexane diamine {(1S,2S)-CHDA} and two extended diamines (1R,2R)-N,N'-bis-(isonicotinoyl)-1,2-diphenylethylene diamine {(1R,2R)-DPEApy} and (1S,2S)-N,N'-bis-(isonicotinoyl)-1,2-cyclohexane diamine {(1S,2S)-CHDApy} chiral guests, are reported. Additions of (1R,2R)-DPEA and (1S,2S)-CHDA separately to 1 in dichloromethane result in the formation of 1:1 sandwich complexes 1·DPEA(R,R) and 1·CHDA(S,S), respectively, at low guest concentration and 1:2 anti complexes 1·(DPEA(R,R))2 and 1·(CHDA(S,S))2, respectively, at higher guest concentration. In contrast, separate additions of (1R,2R)-DPEApy and (1S,2S)-CHDApy to 1 produce only 1:1 sandwich complexes of 1·DPEApy(R,R) and 1·CHDApy(S,S), respectively. The binding constants at 295 K between 1 and (1R,2R)-DPEA are observed to be (4.7 ± 0.2) × 10(4) M(-1) and (4.3 ± 0.3) × 10(3) M(-1) for 1:1 sandwich and 1:2 anti form, respectively, while the respective values with (1S,2S)-CHDA are (1.5 ± 0.2) × 10(5) M(-1) and (5.9 ± 0.3) × 10(3) M(-1). However, much larger values of (2.5 ± 0.3) × 10(5) M(-1) and (1.3 ± 0.3) × 10(6) M(-1) have been observed with DPEApy(R,R) and CHDApy(S,S), respectively, to produce the corresponding 1:1 sandwich complexes. 1·DPEApy(R,R) (Acal, -1759 cm(-1) M(-1)) (Acal = Δε1 - Δε2, representing the total amplitude of the calculated circular dichroism (CD) couplets) shows ∼10-fold increase in CD amplitude compared to the values observed for 1·DPEA(R,R) (Acal, +187 cm(-1) M(-1)), while 1·CHDApy(S,S) (Acal, +1886 cm(-1) M(-1)) shows nearly 3-fold increase of the CD amplitude compared to the value observed for 1·CHDA(S,S) (Acal, -785 cm(-1) M(-1)) at 295 K. The Acal values of -1759 cm(-1) M(-1) and +1886 cm(-1) M(-1) observed for the 1·DPEApy(R,R) and 1·CHDApy(S,S), respectively, are extremely high. To the best of our knowledge, these are some of the largest values reported for a chirality induction process involving bisporphyrin tweezer receptors. The large enhancement in the CD signal intensity is due to the well complementarity size between Zn(II)bisporphyrin host and the extended chiral diamines guest, which results large unidirectional twisting of two porphyrin units to accommodate the guests having preorganized binding sites with minimum host-guest steric interactions. It is interesting to note that 1·DPEA(R,R) and 1·DPEApy(R,R) show CD signal opposite in sign to each other, which happens to be the case between 1·CHDA(S,S) and 1·CHDApy(S,S) also.