Selective binding of glucose-6-phosphate, 3,4-dihydroxyphenylalanine (DOPA) and their analogs with a boronic-acid-appended metalloporphyrin

Chemosensing of neurotransmitters with selectivity and naked eye detection of l-DOPA based on fluorescent Zn(ii)-terpyridine bearing boronic acid complexes

A new range of fluorescent Zn(ii)-terpyridine complexes are described and studied in-depth as chemosensors for catecholamine-based neurotransmitters in pure water.

Boronic acid sensors with double recognition sites: a review

Boronic acids reversibly and covalently bind to Lewis bases and polyols, which facilitated the development of a large number of chemical sensors to recognize carbohydrates, catecholamines, ions, hydrogen peroxide, and so on. However, as the binding mechanism of boronic acids and analytes is not very clear, it is still a challenge to discover sensors with high affinity and selectivity. In this review, boronic acid sensors with two recognition sites, including diboronic acid sensors, and monoboronic acid sensors having another group or binding moiety, are summarized. Owing to double recognition sites working synergistically, the binding affinity and selectivity of sensors can be improved significantly. This review may help researchers to sort out the binding rules and develop ideal boronic acid-based sensors.

A manganese porphyrin–α-cyclodextrin conjugate as an artificial enzyme for the catalytic epoxidation of polybutadiene

A manganese porphyrin–α-cyclodextrin conjugate was designed as an artificial clamp-like enzyme to catalyze the epoxidation of cis-polybutadiene with trans-epoxide preference.

Design and studies of novel polyoxysterol-based porphyrin conjugates

New types of steroid-porphyrin conjugates derived from 20-hydroxyecdysone (20E) and 24-epibrassinolide (EBl) were synthesized. An exceptional regioselectivity in the reaction of both steroids with porphyrin boronic acids was found to give side-chain-conjugated boronic esters as sole products. UV-Vis-, fluorescence and NMR spectroscopy yielded similar data for all the studied compounds confirming the solvent driven supramolecular assembly with formation of J-aggregates. CD measurements of water diluted solutions showed a clear difference between 20E and EBl conjugates. The latter showed a strong supramolecular chirality, whereas 20E J-aggregates did not.

Boronic acid porphyrin receptor for ginsenoside sensing

Ginsenoside detection was pursued through the design of a porphyrin receptor containing two boronic acid units. This receptor was found to undergo different degrees of fluorescence quenching with five ginsenoside guests and an acylated derivative. The trends in the 1:1 binding constants, as well as ESI-HRMS analysis, support a binding mode in which the ginsenoside sugar units are bound to the boronic acid groups, while the steroid core and porphyrin ring participate in hydrophobic interactions.

Design, synthesis and in vitro evaluation of (R)-4-(2-(tert-butylamino)-1-hydroxyethyl)-2-(hydroxymethyl)phenyl hydrogen phenylboronate: a novel salbutamol derivative with high intrinsic efficacy on the β2 adrenoceptor

We tested a set of boron containing arylethanolamine derivatives on the human and guinea pig β(2) adrenoceptor (β(2)AR) 3-D structures by docking methodology. The compound with the highest affinity based on docking analysis, (R)-4-(2-(tert-butylamino)-1-hydroxyethyl)-2-(hydroxymethyl)phenyl hydrogen phenylboronate (boronterol) was synthesized, characterized and tested in guinea pig tracheal rings at basal tone and with histamine-induced contractions. Boronterol was at least eightfold more potent than salbutamol as a smooth muscle relaxant drug (judged by the EC(50) values) and showed a similar maximal relaxant effect as isoproterenol. ICI118,551 showed competitive antagonism on the relaxing effect of boronterol. These results suggest the β(2)AR agonist action of boronterol.

Polyphosphorylated triphenylenes: synthesis, crystal structure, and selective catechol recognition

Designed as a multivalent hydrogen bond acceptor, new receptors, Discopus 1a,b, were built from a triphenylene core surrounded by six (diaryl)phosphinate groups. An efficient synthesis was developed to prepare these elaborated structures in a high overall yield. The X-ray structure of receptor 1b showed strong cooperative hydrogen bonds with two water molecules and intermolecular CH-pi contacts. In chloroform, Discopus 1a,b displayed recognition properties toward dihydroxybenzenes, selectively forming complexes with catechol derivatives 4a-c in a 1:2 (host:guest) stoichiometry. According to NMR and microcalorimetry titrations, association constants were found in the 30-2837 M(-1) range, which were larger than those reported for curvated catechol receptors (14-120 M(-1)). Interestingly, Discopus present two distinct catechol binding sites. Weak hydrogen bonding between host phosphinates and guest hydroxyl groups was shown by infrared spectroscopy and (31)P NMR. Molecular dynamics simulations and recognition experiments suggested that a stronger hydrogen bond assisted by a pi-interaction between the Discopus core and one catechol molecule could exist within the 1:2 complex.

Recognition of phospho sugars and nucleotides with an array of boronic acid appended bipyridinium salts

The solution-phase sensor array of three cationic bis-boronic acid appended benzyl viologens (BBV) and the anionic fluorescent dye, 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS), is able to discriminate among five phospho sugars, four nucleotides and three neutral saccharides in aqueous buffered solution at low mM concentrations. Linear discriminant analysis, principal component analysis, and hierachical cluster analysis studies showed the "discrimination limit" (lowest analyte concentration where the discrimination is still 100%) to be 4mM. Calculated K(b) and F(max)/F(0) values from binding curves of the three BBVs with 1-12 were also used to perform multi-variate analyses with very good discrimination results.

Boronolectins and fluorescent boronolectins: an examination of the detailed chemistry issues important for the design

Glycans in the form of glycoproteins or glycolipids play very critical roles in various biological and pathological processes including inflammation, cancer metastasis, immune reactions, embryo development, cell-cell communications and adhesions, blood generation, etc. Proteins (lectins) that can recognize carbohydrates have played very important roles in studying glycobiology. Small molecule mimics of lectins will be very useful in the development of new therapeutics and diagnostics. Along this line, boronic acids have been widely used in the design and synthesis of small organic compounds that mimic the function of lectins. This review examines in detail the factors that are important for the design of boronic acid-based lectin mimics, boronolectins.

Porphyrins and metalloporphyrins: versatile circular dichroic reporter groups for structural studies

During the last few years, porphyrins and metalloporphyrins have attracted widespread attention as chromophores for studies in circular dichroism (CD), an indispensable chiroptical tool for monitoring chiral interactions. This review summarizes the multifaceted properties of porphyrins and metalloporphyrins, powerful CD chromophores that are characterized by their intense and red-shifted Soret band, propensity to undergo pi-pi stacking, facile incorporation of metals, and ease in varying solubility. Such attributes make porphyrins one of the most attractive and sensitive chromophores used in CD studies. They offer possibilities for studying the stereochemistry of chiral porphyrin assemblies, large organic molecules, biopolymers, and compounds available in miniscule quantities. The tendency of porphyrins to undergo pi-pi stacking and zinc porphyrins to coordinate with amines enable the CD exciton chirality method to be extended to configurational assignments of flexible compounds containing only one stereogenic center. Various artificial porphyrin receptors have been synthesized for the recognition of biologically important chiral guests such as carbohydrates, amino acids, and their derivatives. The induced CD of the host porphyrin Soret band reflects the identity of guests and binding modes of host/guest complexation with high sensitivity.

Visual sensing of saccharides promoted by resorcinol condensation products

[structure: see text] Heating aqueous DMSO solutions of five saccharides in the presence of 1-3 reveals that each receptor promotes solution colors characteristic for each sugar. New compound 3 allows the direct correlation of sugar concentration with visible region absorbance and/or fluorescence intensities.