Synthesis and Photophysical Properties of Dinuclear Organometallic Rhenium(I) Diimine Complexes Linked by Pyridine-Containing Macrocyclic Phenylacetylene Ligands

Fabrication of Hypericin Imprinted Polymer Nanospheres via Thiol-Yne Click Reaction

To fabricate molecularly imprinted polymer nanospheres via click reaction, five different clickable compounds were synthesized and two types of click reactions (azide-alkyne and thiol-yne) were explored. It was found that molecularly imprinted polymer nanospheres could be successfully synthesized via thiol-yne click reaction using 3,5-diethynyl-pyridine (1) as the monomer, tris(3-mercaptopropionate) (tri-thiol, 5) as the crosslinker, and hypericin as the template (MIP⁻NSHs). The click polymerization completed in merely 4 h to produce the desired MIP⁻NSHs, which were characterized by FTIR, SEM, DLS, and BET, respectively. The reaction conditions for adsorption capacity and selectivity towards hypericin were optimized, and the MIP⁻NSHs synthesized under the optimized conditions showed a high adsorption capacity (Q = 6.03 μmol•g-1) towards hypericin. The imprinting factors of MIP⁻NSHs towards hypericin, protohypericin, and emodin were 2.44, 2.88, and 2.10, respectively.

Experimental and theoretical study of the cation binding properties of macrocyclic dehydrodibenzopyrido[15]annulenes

The UV/Vis titration measurements, vibrational and NMR spectroscopy of isomeric dehydrodibenzopyrido[15]annulenes (DBPA) 1 and 2 clearly show that under proper conditions these macrocycles can achieve fast, quantitative and unselective binding of metal ions. The macrocycle 1 is an example of a hindered amine 2,6-bis(R)pyridine and its isomer 2 of a non-hindered amine 3,5-bis(R)pyridine. The protonation stoichiometry for both 1 and 2 was assumed to be DBPA:H(+)=1:1 and the formation constants logK=4.77±0.02 for 1, and logK=6.78±0.08 for 2 were obtained that well agree with those obtained under similar conditions for a macrocycle containing bipyridine units. The protonation of 2 gave the estimated stoichiometry of 2:H(+)=1:1 while the stoichiometric protonation of macrocycle 1 could not be achieved and the lower stability of the ion pair containing 1H(+) is most likely due to the inaccessibility of the nitrogen atom of 1 to the counterions and solvent molecules. The structures and electronic absorption spectra of 1 and 2, as well as the structures and spectra of 1H(+) and 2H(+), i.e. the species formed by protonation of the pyridine nitrogen, were calculated with the time-dependent DFT method with a B3LYP functional and a 6-31+G(d) basis set. The solvent effects were incorporated by means of the polarizable continuum model (PCM). The agreement of the calculated absorption data for the parent and protonated species with the observed spectra is rather satisfactory. Vibrational IR and Raman spectra of 1, 2, 1H(+) and 2H(+) in vacuo were calculated at the B3LYP/cc-pVTZ level of theory. Macrocycles 1 and 2, and their products protonated by trifluoromethanesulfonic acid (1HOTf and 2HOTf) were also characterized by temperature-dependent FTIR technique known as two dimensional IR correlation analysis. Quite large difference in degradation temperature between macrocycle 1 and 2 and their protonated complexes was measured, indicating that inclusion of proton leads to significant thermal stabilization of dehydroannulene ring.

Self-assembly of oxamidato bridged ester functionalised dirhenium metallastirrups: synthesis, characterisation and cytotoxicity studies

Hetero-topic self-assembly of Re₂(CO)₁₀ with oxamide ligands and ester-functionalised flexible ditopic-tectons afforded dinuclear metallacycles resembling a stirrup. The metallastirrups showed promising cytotoxic activity against few cancer cell lines in vitro.

One-pot synthesis of oxamidato-bridged hexarhenium trigonal prisms adorned with ester functionality

The self-assembly of hexarhenium trigonal prisms using fac-Re(CO)₃ cores (pink), bischelating oxamide ligands (green) and ester-containing tritopic linkers (blue) has been accomplished via an orthogonal bonding approach.

One-step synthesis of dual clickable nanospheres via ultrasonic-assisted click polymerization for biological applications

Dual clickable nanospheres (DCNSs) were synthesized in one step using an efficient approach of ultrasonic-assisted azide-alkyne click polymerization, avoiding the need of surfactants. This novel approach presents a direct clickable monomer-to-nanosphere synthesis. Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and dynamic laser scattering (DLS) were used to characterize the synthesized DCNSs. Numerous terminal alkynyl and azide groups on the surface of DCNSs facilitate effective conjugation of multiple molecules or ligands onto a single nanocarrier platform under mild conditions. To exemplify the potential of DCNSs in biological applications, (1) multivalent glyconanoparticles (GNPs) were prepared by clicking DCNSs with azide-functionalized and alkyne-functionalized lactose sequentially for the determination of carbohydrate-galectin interactions with quartz crystal microbalance (QCM) biosensor. Using protein chip (purified galectin-3 coated on chip) and cell chip (Jurkat cells immobilized on chip), the QCM sensorgrams showed excellent binding activity of GNPs for galectins; (2) fluorescent GNPs were prepared by clicking DCNSs with azide-functionalized Rhodamine B and alkyne-functionalized lactose sequentially in order to target galectin, which is overexpressed on the surface of Jurkat cells. The fluorescent images obtained clearly showed the cellular internalization of fluorescent GNPs. This fluorescent probe could be easily adapted to drugs to construct lectin-targeted drug delivery systems. Thus, DCNSs prepared with our method may provide a wide range of potential applications in glycobiology and biomedicine.

Preparation of shape-persistent macrocycles with a single pyridine unit by double cross-coupling reactions of aryl bromides and alkynes

A double Sonogashira-type coupling reaction between aryl bromides and alkynes using a catalytic Pd/XPhos (2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl) system was introduced as an efficient method for the synthesis of shape-persistent macrocycles (SPMs). This approach is advantageous in the synthesis of SPMs with a single pyridine unit.

Inorganic-Cored Photoactive Assemblies: Synthesis, Structure, and Photochemical Investigations on Stannoxane-Supported Multifluorene Compounds

Organostannoxanes were used as inert supports for the preparation of multichromophore assemblies. The synthesis involves a single-step procedure and allows the preparation of compounds in which the number of chromophore units can be varied from one to six. Thus, the reactions of LCOOH (1-fluorenecarboxylic acid) or L'COOH (9-fluorenecarboxylic acid) with various organostannoxane precursors afforded the fluorenyl derivatives [Ph(3)SnO(2)CL] (1), [Ph(3)SnO(2)CL'] (2), [{nBu(3)SnO(2)CL''}(n)] (3), [{nBu(3)SnO(2)CL'}(n)] (4), [{tBu(2)Sn(OH)O(2)CL}(2)] (5), [{tBu(2)Sn(OH)O(2)CL'}(2)] (6), [{[nBu(2)SnO(2)CL](2)O}(2)] (7) [{[nBu(2)SnO(2)CL'](2)O}(2)] (8), [{nBuSn(O)O(2)CL}(6)] (9), and [{nBuSn(O)O(2)CL'}(6)] (10). Interestingly, the formation of 3 is accompanied by an unusual oxo-transfer reaction. The ligand L is oxidized at the 9-position. Compounds 1, 3, 5, 7, and 8 were characterized by X-ray crystallography. The solid-state structures of these compounds reveal rich supramolecular structures owing to multiple intermolecular interactions between the various supramolecular synthons present in these molecules. The optical behavior of 1-10 is primarily dictated by the fluorenyl periphery. These compounds display strong blue fluorescent emission in solution and blue-green fluorescent emission in the solid state. Fluorescence lifetimes of all of these compounds are on the nanosecond timescale, and this suggests that the emission originates from the singlet excited state to the ground state. Intermolecular interactions in the solid state lead to considerable broadening of the emission bands.