Amorphous nanoparticles of supramolecular coordination polymer networks are spontaneously self-assembled from nucleotides and lanthanide ions in water. They show intrinsic functions such as energy transfer from nucleobase to lanthanide ions and excellent performance as contrast enhancing agents for magnetic resonance imaging (MRI). Furthermore, adaptive inclusion properties are observed in the self-assembly process: functional materials such as fluorescent dyes, metal nanoparticles, and proteins are facilely encapsulated. Dyes in these nanoparticles fluoresce in high quantum yields with a single exponential decay, indicating that guest molecules are monomerically wrapped in the network. Gold nanoparticles and ferritin were also wrapped by the supramolecular shells. In addition, these nucleotide/lanthanide nanoparticles also serve as scaffolds for immobilizing enzymes. The adaptive nature of present supramolecular nanoparticles provides a versatile platform that can be utilized in a variety of applications ranging from material to biomedical sciences. As examples, biocompatibility and liver-directing characteristics in in vivo tissue localization experiments are demonstrated.

Dynamic covalent functionality has been acknowledged as a powerful tool for the construction of organised architectures, the reversible nature thermodynamically facilitates self-control and self-correction. The use of boronic acids complexation with diols and their congeners has already shown great promise in realising and developing reversible boron-containing multicomponent systems with dynamic covalent functionality. The structure-directing potential has lead to the development of a variety of self-organisation involving not only macrocycles, cages and capsules, but also porous covalent organic frameworks and polymers. Structure controls as well as remarkable synthesis are highlighted in this feature article.

The self-aggregation of cationic porphyrins in aqueous solution has been studied by means of absorption, 1 H NMR, and resonance light scattering spectroscopy. The aim of the present study is clarification of the factors which most influence porphyrin self-aggregation in water. Cationic 5,10,15,20-tetrasubstituted porphyrins [PorSub 4 : PC3Py (Sub ) -(CH 2 ) 3 -Py + Cl -), PC5Py (Sub ) -(CH 2 ) 5 -Py + Cl -), PC7Py (Sub ) -(CH 2 ) 7 -Py + Cl -), TPPOC2Py (Sub ) p-C 6 H 4 -O(CH 2 ) 2 -Py + Br -), and TPPOC3Py (Sub ) p-C 6 H 4 -O(CH 2 ) 3 -Py + Br -), where Py + ) N-alkylpyridinium] were used. PC3Py forms a dimer in aqueous solution with or without an added inorganic salt. In the presence of KNO 3 , dimer formation of PC3Py is dominated by a large and negative enthalpy change. The entropy change for aggregation increases with increasing concentrations of added KNO 3 , while enthalpy changes are almost constant. The thermodynamic parameters suggest that dimer formation of PC3Py is the result of a large enthalpic gain due to extended van der Waals interactions, in cooperation with enhanced hydrophobic interactions. Electrostatic repulsion suppresses further association. However, other cationic porphyrins studied show evidence of higher self-aggregate formation. X-ray crystallographic studies of PC5Cl (Sub ) -(CH 2 ) 5 -Cl), a precursor of PC5Py, show the formation of a slipped face-to-face dimer as the basic unit for forming a crystal lattice, while that of TPP (Sub ) -C 6 H 5 ) indicates the absence of face-to-face stacking interaction in the crystals. Judging from these results, it is assumed that the slipped face-to-face dimer is the unit of the higher self-aggregates of PC5Py or PC7Py in water with or without KNO 3 . Elongated alkyl chains of PC5Py and PC7Py may be responsible by enhancing hydrophobic interaction of the porphyrins studied. TPPOC2Py alone forms a J-aggregate, characterized by a sharp and red-shifted Soret band and a strongly enhanced resonance light scattering signal. Higher self-aggregates having face-to-face arrangement are formed with TPPOC3Py; these provide no enhanced RLS feature. The present study reveals the dependence of aggregate formation of water-soluble porphyrins on the peripheral mesosubstituents.

In this feature article the use of boronic acids to monitor, identify and isolate analytes within physiological, environmental and industrial scenarios is discussed. Boronic acids recognise diol motifs through boronic ester formation and interact with anions generating boronates, as such they have been exploited in sensing and separation protocols for diol appended molecules such as saccharides and anions alike. Therefore robust molecular sensors with the capacity to detect chosen molecules selectively and signal their presence continues to attract substantial attention, and boronic acids have been exploited with some success to monitor the presence of various analytes. Reversible boronic acid-diol interactions have also been exploited in boron affinity chromatography realising new separation domains through the same binding events. Boronic acid diol and anion interactions pertaining to sensing and separation are surveyed.

Two heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TMe-beta-CD) molecules strongly include the peripheral substituents at the 5- and 15-positions of the charged meso-tetrasubstituted porphyrins, PorSub(4) [TPPS(4) (Sub = p-C(6)H(4)-SO(3)(-)), TPPOC3PS (p-C(6)H(4)-O-(CH(2))(3)-p-C(6)H(4)-SO(3)(-)), TCPP (Sub = p-C(6)H(4)-CO(2)(-)), and TPPOC3Py (p-C(6)H(4)-O-(CH(2))(3)-Py(+)Br(-)), where Py(+) = N-alkylpyridinium] in aqueous ethylene glycol. The binding constants (K(1) and K(2)) and the rate constants (k(1) and k(2)) for formation of the 1:1 and 2:1 complexes of TMe-beta-CD and PorSub(4) were determined. Both the binding constants and the rate constants for anionic TPPS(4), TCPP, and TPPOC3PS were much larger than those for cationic TPPOC3Py. The smaller k(1) and k(2) values for TPPOC3Py indicate a higher barrier for penetration of a cationic guest into the TMe-beta-CD cavity. The methyl groups at the rims and the cavity wall of the host are positively polarized due to the inductive effect of the ethereal oxygens. The positively polarized rims and interior of the host cavity should prevent the penetration of the cationic substituent of TPPOC3Py into the TMe-beta-CD cavity. The 2:1 TMe-beta-CD-PorSub(4) complexes are extraordinary stable in aqueous solutions, even in the case of cationic TPPOC3Py. Formation of both 1:1 and 2:1 complexes is promoted by negative and large enthalpy changes, suggesting a strong van der Waals interaction as the main binding force.

Reliable sensing of structurally similar anions in water is a difficult problem, and analytical tests and sensor devices for reliable sensing of multiple anions are very rare. This study describes a method for fabrication of simple colorimetric array-based assays for aqueous anion solutions, including complex analytes encountered in real-life applications. On the fundamental level, this method shows how the discriminatory capacity of sensor arrays utilizing pattern recognition operating in multianalyte environments may be dramatically improved by employing two key features. The synergy between the sensor and hydrogel host resembles the cooperative effects of an apoenzyme and cofactor: the host hydrogel helps extract the target anions from the bulk analyte while stripping the solvate molecules off the anions. In addition, the supramolecular studies of the affinity and selectivity of the potential sensors for target analytes allow for constructing an array predesigned for a particular analyte. To illustrate both aspects, an eight-sensor array utilizing colorimetric sensor materials showing selectivity for fluoride and pyrophosphate while displaying significant cross-reactivity for other anions such as carboxylates, phosphate, or chloride was used to differentiate between 10 anions. The quantitative analyses were also performed to show that the eightsensor array was found to operate across 4 orders of magnitude concentrations (0.20-360 ppm; 10 µM to 20 mM). The applicability of this approach was demonstrated by analyzing several toothpaste brands. The toothpastes are complex analytes comprising both known and unknown anions in various concentrations. The fluoride-selective yet cross-reactive array is shown to utilize the fluoride content as the main differentiating factor while using the remaining anionic components for further differentiation between toothpaste brands.

A supramolecular sensor array consisting of eight chemosensors embedded in a hydrogel matrix was used to sense carboxylate drugs. The discriminatory power of the array has been evaluated using principal component analysis and linear discriminant analysis. The eight-member sensor array has been shown to accurately identify 14 carboxylates in water with 100% classification accuracy. To demonstrate the potential for practical utility in the physiological environment, analysis of carboxylate drugs in human urine was also performed achieving 100% correct classification. In addition, the array performance in semiquantitative identification of nonsteroidal anti-inflammatory drugs has been investigated, and the results show that the sensor array is able to differentiate six typical nonsteroidal anti-inflammatory drugs at concentrations of 0.5-100 ppm. This illustrates the potential utility of the designed sensor array for diagnostic and environmental monitoring applications.

We present a simple, two- or three-step method for the synthesis of chromogenic octamethylcalix[4]pyrrole-based (OMCP) sensors for anions. Electrophilic aromatic substitution allows for converting the pyrrole moieties of OMCP into a dye. The formation of a sensor-anion complex results in partial charge transfer and a dramatic change in color. The absorption (UV-vis) and NMR titration experiments show that the chromogenic OMCPs sense anions administered as aqueous solutions, even at high ionic strength ( approximately 0.1 M NaCl), while displaying selectivity for pyrophosphate and carboxylate anions. The experiments with polyurethane sensor films show a strong response for aqueous carboxylates, such as antipyretics naproxen approximately ibuprofen > salicylate, without being biased by bicarbonate or carboxy termini of blood plasma proteins.