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The development of chemical sensors is an urgent need for both environmental and health issues. The breakthrough needed for the advancement of these devices is the development of efficient receptors. Porphyrins have been widely used as sensing layers in chemical sensors, but their integration with nanostructures can greatly boost the performance of these macrocycles, improving from one side the stability of the sensing layer, and from the other, offering additional interaction mechanisms with target analytes. We present here some recent examples of hybrid materials prepared by the integration of porphyrins with metal and metal oxide nanoparticles, porphyrin-based metal organic frameworks and their exploitation as sensing layers in chemical sensors.

Two synthetic routes for the preparation of the water soluble 5,10,15‐tris(4‐sulfonatophenyl)corrole are reported. The first approach explores the chlorosulfonation reaction on the phosphorus complex of 5,10,15‐tris(4‐trimethylsilylphenyl)corrole. Following this route, the P complex of the target corrole has been obtained in low yields, while the major product was the tetrasubstituted complex, with the additional sulfonyl group regioselectively introduced at the 2‐position. To widen the scope of the reaction, the direct preparation of the 5,10,15‐tris(4‐sulfonatophenyl)corrole has been pointed out, affording both the target corrole and the intermediate chlorosulfonyl derivative in reasonable yields. The photophysical properties and the protonation equilibria of both corroles have been investigated, showing that 5,10,15‐tris(4‐sulfonatophenyl)corrole does not aggregate in acidic solutions, different from the analogous porphyrin.

Porphyrins and carbon nanomaterials are among the most widely investigated and applied compounds, both offering multiple options to modulate their optical, electronic and magnetic properties by easy and well-established synthetic manipulations. Individually, they play a leading role in the development of efficient and robust chemical sensors, where they detect a plethora of analytes of practical relevance. But even more interesting, the merging of the peculiar features of these single components into hybrid nanostructures results in novel materials with amplified sensing properties exploitable in different application fields, covering the areas of health, food, environment and so on. In this contribution, we focused on recent examples reported in literature illustrating the integration of different carbon materials (i.e., graphene, nanotubes and carbon dots) and (metallo)porphyrins in heterostructures exploited in chemical sensors operating in liquid as well as gaseous phase, with particular focus on research performed in the last four years.

The impressive chemistry shown by porphyrins in natural systems is particularly attractive for exploitation in chemical sensors. In these devices the sensing mechanisms can mimic most of the porphyrin biological reactivity, such as reversible binding, activation of small molecules, redox activity, and photoactivated processes. The simultaneous presence of multiple binding mechanisms allows porphyrins to interact with a large variety of analytes. This feature reduces the selectivity, but prompts the development of sensor arrays, where the cross-selectivity of more sensors is used to classify and identify samples characterized by a complex composition. Since 1995 the Sensors Group of the University of Rome Tor Vergata has exploited these features to prepare sensor arrays based on different transducers and aimed at several applications. These kinds of devices have been reported as electronic noses (gaseous phase analytes) and electronic tongues (liquid phase analytes) to underline that their working mechanisms are tentatively similar to that of biological senses. We report here some of the results obtained.

Porphyrins and related macrocycles have been intensively exploited as sensing materials in chemical sensors, since in these devices they mimic most of their biological functions, such as reversible binding, catalytic activation, and optical changes. Such a magnificent bouquet of properties allows applying porphyrin derivatives to different transducers, ranging from nanogravimetric to optical devices, also enabling the realization of multifunctional chemical sensors, in which multiple transduction mechanisms are applied to the same sensing layer. Potential applications are further expanded through sensor arrays, where cross-selective sensing layers can be applied for the analysis of complex chemical matrices. The possibility of finely tuning the macrocycle properties by synthetic modification of the different components of the porphyrin ring, such as peripheral substituents, molecular skeleton, coordinated metal, allows creating a vast library of porphyrinoid-based sensing layers. From among these, one can select optimal arrays for a particular application. This feature is particularly suitable for sensor array applications, where cross-selective receptors are required. This Review briefly describes chemical sensor principles. The main part of the Review is divided into two sections, describing the porphyrin-based devices devoted to the detection of gaseous or liquid samples, according to the corresponding transduction mechanism. Although most devices are based on porphyrin derivatives, seminal examples of the application of corroles or other porphyrin analogues are evidenced in dedicated sections.

A diiminoisoindolo-pyrazino unit was annulated to the β-pyrrolic position of the Zn complex of tetraphenylporphyrin, giving a macrocycle with an expanded π system in satisfactory yields. The crystal structure of this derivative evidenced the formation of a hydrogen bond network. The interaction of the β-fused isoindoline porphyrin derivative with nucleotides and nucleic acids has been investigated.

Hierarchical self-assembly of porphyrins is an intrigue research field, which can lead to the design of functional materials. Porphyrin derivatives self-assembling under hierarchical control allows to understand the principles governing molecular recognition processes, as demonstrated for meso-tetrakis(4-phosphonatophenyl)porphyne (H2TPPP) whose polyprotic nature is responsible for a pH-dependent hierarchical aggregation. Herein, self-assembly of meso-tris(4-phosphonatophenyl)corrole (TPPC) in aqueous solution has been spectroscopically studied and compared to that of TPPP. The corrole aggregation does not follow the hierarchical rules that govern the porphyrin counterpart due to the accessibility of the core of the macrocycle to protons, promoted by the reduced number of involved intermolecular H-bonds.

The construction of nanosized supramolecular hosts via self-assembly of molecular components is a fascinating field of research. Such intriguing class of architectures, beside their intrinsic intellectual stimuli, is of importance in many fields of chemistry and technology, such as material chemistry, catalysis, and sensor applications. Within this wide scenario, tailored solid films of porphyrin derivatives are structures of great potential for, among others, chemical sensor applications. The formation ofsupramoleculesrelays on noncovalent interactions (electrostatic, hydrogen bond, , or coordinative interactions) driven by the chemical information stored on the assembling molecules, such as shape and functional groups. This allows, for example, the formation of large well-defined porphyrin aggregates in solution that can be spontaneously transferred onto a solid surface, so achieving a solid system with tailored features. These films have been used, covering the bridge between nanostructures and microsystems, for the construction of solid-state sensors for volatiles and metal ion recognition and detection. Moreover, the variation of peripheral substituents of porphyrins, such as, for example, chiral appended functionalities, can result in the formation of porphyrin aggregates featuring high supramolecular chirality. This would allow the achievement of porphyrin layers characterised by different chiroptical and molecular recognition properties.

Metalloporphyrins offer almost unique opportunities to design artificial receptors for chemical sensors. These molecules can be tailored, at the synthetic level, changing in a rational way the sensor selectivity that can be oriented toward desired analyte families. Since porphyrins showed interesting properties as ionophors in liquid phase, they have been widely used to develop ion selective electrodes. These electrochemical sensors grouped in a matrix and supported by a suitable pattern recognition analysis constituted a system called electronic tongue. The present work describes in some detail the operating principle of a electronic tongue multisensor system, and a number of chemical images, coming from biological, environmental or food samples, obtained as a result of the exploitation of the device.

Herein we report the preparation of hybrid Co porphyrin-SnO2 thin films by sol-gel technique and a study of their sensing properties. The porphyrin structure bears a carboxylic group to improve its stabilization into the oxide matrix. SEM characterization of the spin-coated thin films deposited onto alumina substrates showed a homogeneously morphology. These CoTCPP-SnO2 sensors showed fast and reversible responses towards the detection of methanol vapors and highest responses were obtained at the working temperature of 250 degreesC. Optical characterization of the heated CoTCPP-SnO2 thin films indicated that the metalloporphyrin is still present after heating up to 320 degreesC, while it was completely decomposed after thermal treatment at 400 degreesC. These results support the presence of a catalytic effect of the CoTCPP at lower temperature, which induces a significant increase in the sensor responses at 250 degreesC, while at higher temperature, where the porphyrin is thermally decomposed, the hybrid CoTCPP-SnO2 sensors behave similarly to pure SnO2 devices. On the contrary, no significant differences in the sensor responses where observed in the case of CO detection, showing that metalloporphyrins can be used to modify the selectivity of SnO2 sensors.

The richness of properties showed by porphyrins and related compounds has attracted the attention of researchers for many years, because the attempt to mimic the essential role that these macrocycles have in nature make them of potential interest as organic materials in a number of application fields. Many of these exploitations require the presence of diverse functionalities on the peripheral positions of the tetrapyrrolic macrocycles, to finely tune the porphyrin properties or to covalently attach them to a particular substrate. For this reason in the last decade a particular attention has been focused on the developments of rational or statistical synthetic protocols, aimed for the preparation of unsymmetrically substituted porphyrin derivatives.

A novel method for the preparation of beta-fused porphyrin dyads was developed that exploits a one-pot reaction of 2,3-diaminoporphyrins with diethyl oxalate. This approach provides good yields of the zinc beta-fused dyad and the corresponding free-base, opening the way for preparation of several metal derivatives to permit modulation of optoelectronic characteristics for commercial applications. (C) 2013 Elsevier Ltd. All rights reserved.

Porphyrins and related macrocycles have been widely exploited as sensing layers of different kind of chemical sensors. Among the different porphyrin analogs, corrole has been object of an increasing attention in the last few years; because of its peculiar coordination chemistry, corrole can be a useful system to study the influence of analytes coordination in an overall sensing mechanism. We have synthesized different corrole derivatives in order to use them as sensing layers of nanogravimetric chemical sensors. The resulting sensors have been exposed to volatile organic compounds and gases chosen as model analytes. Sensors performances have been compared with those of similar devices functionalized with analogous porphyrin derivatives. The results show that in the case of corrole the supramolecular binding mechanism is more efficient than coordination for CO and NO detection, and that the two binding mechanisms can actually cooperate to increase the sensitivity. © 2012 Elsevier B.V. All rights reserved.

Two different methods for the regioselective nitration of different meso-triarylcorroles leading to the corresponding β-substituted nitrocorrole iron complexes have been developed. A two-step procedure affords three Fe(III) nitrosyl products-the unsubstituted corrole, the 3-nitrocorrole, and the 3,17-dinitrocorrole. In contrast, a one-pot synthetic approach drives the reaction almost exclusively to formation of the iron nitrosyl 3,17-dinitrocorrole. Electron-releasing substituents on the meso-aryl groups of the triarylcorroles induce higher yields and longer reaction times than what is observed for the synthesis of similar triarylcorroles with electron-withdrawing functionalities, and these results can be confidently attributed to the facile formation and stabilization of an intermediate iron corrole π-cation radical. Electron-withdrawing substituents on the meso-aryl groups of triarylcorrole also seem to labilize the axial nitrosyl group which, in the case of the pentafluorophenylcorrole derivative, results in the direct formation of a disubstituted iron μ-oxo dimer complex. The influence of meso-aryl substituents on the progress and products of the nitration reaction was investigated. In addition, to elucidate the most important factors which influence the redox reactivity of these different iron nitrosyl complexes, selected compounds were examined by cyclic voltammetry and thin-layer UV-visible or FTIR spectroelectrochemistry in CH 2Cl 2. © 2012 American Chemical Society.

Functionalization of the β-pyrrolic positions of the corrole macrocycle with -NO 2 groups is limited at present to metallocorrolates due to the instability exhibited by corrole free bases under oxidizing conditions. A careful choice of the oxidant can limit the transformation of corroles into decomposition products or isocorrole species, preserving the corrole aromaticity, and thus allowing the insertion of nitro groups onto the corrole framework. Here we report results obtained by reacting 5,10,15-tritolylcorrole (TTCorrH 3) with the AgNO 2/ NaNO 2 system, to give mono- and dinitrocorrole derivatives when stoichiometry is carefully controlled. Reactions were found to be regioselective, affording the 3-NO 2TTCorrH 3 and 3,17-(NO 2) 2TTCorrH 3 isomers as the main products in the case of mono- and disubstitution, in 53 and 20% yields, respectively. In both cases, traces of other mono- and disubstituted isomers were detected, which were structurally characterized by X-ray crystallography. The influence of the β-nitro substituents on the corrole properties is studied in detail by UV-visible, electrochemical, and spectroelectrochemical characterization of these functionalized corroles. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations of the ground and excited state properties of these β-nitrocorrole derivatives also afforded significant information, closely matching the experimental observations. It is found that the β-NO 2 substituents conjugate with the π-aromatic system of the macrocycle, which initiates significant changes in both the spectroscopic and redox properties of the so functionalized corroles. This effect is more pronounced when the nitro group is introduced at the 2-position, because in this case the conjugation is, for steric reasons, more efficient than in the 3-nitro isomer. © 2012 American Chemical Society.

Porphyrin and related macrocycles have been widely exploited as sensing materials in chemical sensors. The performances of such materials are generally depicted in terms of the binding properties of the individual molecule, but we have recently showed that the supramolecular aggregation of the macrocycles in the solid films could offer additional binding mechanisms, enhancing the sensing properties of the material. Among the different porphyrin analogs, corrole has attracted an increasing interest, due to its peculiar properties, demonstrated as sensing material in the case of carbon monoxide detection. We report here the sensing performances of corrole aggregates deposited to functionalize quartz crystal microbalances. The porous nanostructures of the organic framework offer additional binding mechanisms not available to the individual receptor, so allowing enhanced performances as sensing material.

Bromination of 3-nitro-5,10,15-triarylcorrole selectively provides two regioisomers, depending on the reaction pathway. An isocorrole species is the key intermediate to drive the reaction towards the 2-Br-17-nitro regioisomer. © 2011 The Royal Society of Chemistry.

5,10,15,20-Tetrakis(3,5-dihydroxyphenyl)porphyrin metal derivatives have been exploited as porous sensing layers to functionalize nanogravimetric chemical sensors. Their sensing performances have been tested by exposing the devices to different concentration of volatile compounds. While the peripheral substitution of porphyrin from one side allowed the formation of porous thin films, the other significantly oriented the sensor selectivities towards analytes able to interact by hydrogen bonding. A more intriguing result was the unexpected sensitivity observed toward CO detection, which cannot be ascribed to the CO coordination to the metalloporphyrin sensing layer. In this case the sensing mechanism is due to the entrapment of CO inside the porous porphyrin network, confirming that supramolecular porphyrin aggregates offer a sensing mechanism not available to the single molecular unit. © 2011 The Royal Society of Chemistry.

Mono- and di-substituted β-nitro derivatives have been obtained from the reaction of ttcorrFeCl with sodium nitrite in refluxing DMF. This result is unprecedented for iron corrolates and further evidences the non-innocent character of the corrole ligand. © 2011 The Royal Society of Chemistry.

The construction of nanosized supramolecular hosts via self-assembly of molecular components is a fascinating field of research. Such intriguing class of architectures, beside their intrinsic intellectual stimuli, is of importance in many fields of chemistry and technology, such as material chemistry, catalysis, and sensor applications. Within this wide scenario, tailored solid films of porphyrin derivatives are structures of great potential for, among others, chemical sensor applications. The formation of supramolecules relays on noncovalent interactions (electrostatic, hydrogen bond, 𝜋-𝜋, or coordinative interactions) driven by the chemical information stored on the assembling molecules, such as shape and functional groups. This allows, for example, the formation of large well-defined porphyrin aggregates in solution that can be spontaneously transferred onto a solid surface, so achieving a solid system with tailored features. These films have been used, covering the bridge between nanostructures and microsystems, for the construction of solid-state sensors for volatiles and metal ion recognition and detection. Moreover, the variation of peripheral substituents of porphyrins, such as, for example, chiral appended functionalities, can result in the formation of porphyrin aggregates featuring high supramolecular chirality. This would allow the achievement of porphyrin layers characterised by different chiroptical and molecular recognition properties.

The reaction of 5,10,15-triarylcorrole with 4-amino-4H-1,2,4-triazole provides another example of corrole ring expansion to give the corresponding 6-azahemiporphycene, a novel porphyrin analogue. The facile oxidation of the corrole ring is a required step for the ring expansion and for this reason the reaction fails in the case of corroles bearing meso-phenyl groups carrying electron-withdrawing substituents. Steric requirements also limited the scope of the reaction, which is not successful in the case of 2,6-disubstituted meso-aryl corroles. The occurrence of an initial oxidation is further supported by formation of the 6-azahemiporphycene derivative when the reaction is carried out under the same conditions, using a 5- or a 10-isocorrole as starting material. 1H NMR spectra and X-ray crystal characterization of 6-azahemiporphycene evidenced the presence of an intramolecular N;H 3 3 3 N hydrogen bond in the inner core of the macrocycle, while photophysical characterization confirmed the aromatic character of the novel macrocycle, showing an intense Soret-like band around 410 nm in the absorption spectrum. The fluorescence emission is very modest, and 6-azahemiporphycene showed higher photostability than the corresponding corrole species. Different metal complexes of 6-azahemiporphycene were prepared following synthetic protocols usually exploited for the preparation of metalloporphyrins, demonstrating good coordination properties for the macrocycle. Both the free-base and metal derivatives were characterized by cyclic voltammetry and spectroelectrochemistry in dichloromethane and benzonitrile. To further detail the behavior of this novel macrocycle, density functional theory (DFT) calculations were carried out on the basic structure of 6-azahemiporphycene with the aim of assessing aromaticity and tautomerism, as well as calculating its stability with respect to the 5-aza isomer.

Corrole is one of the first examples of porphyrin analogs reported in the literature. This class of compounds has received a great attention, because of their promising exploitation in different fields, ranging from medicine to material chemistry. Among them, corrole can be considered the prototypical example of contracted porphyrins, with one of the meso carbon bridges missing. Although this macrocycle was first reported more than thirty years ago, only recently more attention has been devoted to the chemistry of corrole. The recent availability of efficient and facile syntheses of meso-substituted corroles has probably been the shuttle for the impressive flourishing of corrole-related papers appearing in literature in the last few years. The aim of this review is to highlight the latest reports in the synthetic chemistry of corrole, with special attention to the synthetic strategies and peripheral functionalizations of this macrocycle.

Novel dyads in which a porphyrin ring is directly fused through two β-pyrrolic carbons to a BODIPY® moiety have been prepared using a stepwise approach starting from the copper(II) complex of pyrrolo[2,3-c]-5,10,15,20-tetraphenylporphyrin. Formylation and reaction with 3,5-dimethylpyrrole afforded 8; subsequent BF2 complexation gave the TPP-BODIPY® dyad in reasonable yields. Demetalation in TFA/H2SO4 led to the corresponding free base 12, opening the way to the subsequent preparation of the Zn complex 13. Both 12 and 13 exhibited complex optical spectra with an intensely red-shifted Q-band. Luminescence spectra displayed a very intense band around 700 nm making these species suitable as near-IR dyes and sensors in biological media. Optical analyses of 12, using the INDO/SCI technique, were performed to obtain information to establish the origin of the novel optical properties. These studies showed that the optical properties of 12 cannot be attributed to deformation of the molecular skeleton, but derive from the increased extension of the conjugation between the TPP and BODIPY® π-systems.

Hierarchy is a powerful and promising tool to rationally synthesize non-covalent complex species. In this paper we show two different examples of hierarchically driven aggregation processes allowing for the control of aggregation state or “shape” of the final species. In the first case we propose that water-soluble porphyrins presenting various protonation steps can follow kinetic routes alternative to the thermodynamic pathway; namely for each protonation step is allowed, in principle, an alternative kinetically driven homo-self-aggregation process. Our results indicate that the thermodynamic route leads to a monomeric, protonated final state, but the kinetic pathway ends with self-assemblies of the title porphyrin. The bias between the two final states can be easily pre-determined by going quickly or slowly throughout the thermodynamic–kinetic junction. The second case deals with the so-called “chiral memory” phenomenon. Also in this case the role of the kinetic control over the assembly process is remarkable. In particular, we have observed that self-aggregation of opposite charged, achiral porphyrins does not lead to induced chirality even if a chiral template is added after their aggregation. The final aggregates are kinetically inert, mostly because stabilized by a network of electrostatic interactions between net charges. However, if the two supramolecular components are mixed in the presence of a chiral template, then an induced circular dichroism signal (ICD) appears in the Soret region (the main absorption feature of porphyrins in the visible region whose maximum and intensity are strongly affected by the aggregation state). Removal of the template does not significantly affect the intensity of the ICD: the inert aggregates have memorized the chiral template shape. Remarkably, these species – now inherently chiral – act as very efficient templates for self-aggregation of additional non-chiral porphyrins.

In aqueous solution meso-tetrakis(4-phosphonatophenyl)porphyrin shows self-aggregation processes controlled by the "sergeant-soldier rule". After partial protonation of the external phosphonic groups, it is possible (i) to further protonate the inner nitrogen atoms of the molecules or (ii) to allow, over time, the system to aggregate. Therefore, the two procedure lead to a different system evolution, producing species with different chemico-physical properties.

Thin films consisting of a fulleropyrrolidine derivative 1 and a novel water-soluble porphyrin 2 were prepared by the Langmuir–Sh+fer (LS, horizontal lifting) method. In particular, a solution of 1 in chloroform and dimethyl sulfoxide was spread on the water surface, while porphyrin 2 (bearing peripheral anionic groups) was dissolved into the aqueous subphase. To the best of our knowledge, such a versatile method of film fabrication for fullerene/porphyrin mixed composite films has never been used before. Evidence of the effective interactions between the two moieties at the air– water interface was obtained from the analysis of the floating layers by means of surface pressure versus area per molecule Langmuir curves, Brewster angle microscopy and UV-visible reflection spectroscopy. The characterisation of the LS films by UV-visible spectroscopy reveals that the two constituents behave as discrete and weakly interacting p systems. The use of polarised light suggests the existence of a preferential direction of the macrocyclic rings with an edge-on arrangement with respect to the substrate surface. Finally, photoaction spectra were recorded from films deposited by only one horizontal lifting onto indium–tin– oxide (ITO) electrodes and the observed photocurrent increased notably with increasing transfer surface pressure.

The Rothemund condensation reaction of pyrrole and aldehydes is an extensively used route to meso-tetraarylporphyrins, but simple modifications of the reaction conditions allow the formation of different macrocycles other than the expected porphyrin. In the presence of an excess of pyrrole, this modified Rothemund approach leads to the synthesis of meso-triary-substituted corroles. This methodology allows the preparation of a wide range of substituted corroles starting from commercially available products. Higher yields have been obtained in the case of benzaldehydes bearing electron-withdrawing substituents, while the reaction fails in the presence of 2,6-disubstituted benzaldehydes. Although if not isolated, some experimental evidences indicate that the linear 5,10,15-triphenylbilane 4 is the precursor of the final corrole ring. Reaction of 5,10,15-triphenylcorrole 2 with an excess of NBS leads to the complete bromination of the macrocycle. Spectroscopic characterization seems to indicate the formation of the porphodimethene-like structure 5, where the macrocyclic aromatic conjugation is interrupted at the 10 position. Metalation of this compound with cobalt acetate and PPh3 affords the corresponding complex. The X-ray crystal structure of triphenylphosphine [2,3,7,8,12,13,17,18-octabromo-5,10,15-tris(4-nitrophenyl)corrolato]- cobalt(III) 8 confirms the ability of corrole ring to retain an almost planar conformation when fully substituted at the peripheral position.

A comparative study of Pt(II)- and Pt(IV)-porphyrins as novel ionophores for anion-selective polymeric membrane electrodes is performed. Polymeric membranes of different compositions, prepared by varying plasticizers, cationic and anionic additives and Pt porphyrins, have been examined by potentiometric and optical techniques. Pt porphyrin-based devices were found to exhibit enhanced potentiometric selectivity toward iodide ion compared to electrodes based on a typical anion-exchanger (e.g. tridodecylmethylammonium chloride). It is shown that Pt(II)-porphyrins function as neutral anion carriers within the electrode membranes, while those based on Pt(IV)TPPCl(2) operate via a mixed mode carrier mechanism, evidencing also a partial reduction of the starting ionophore to Pt(II)TPP. Spectrophotometric measurements of thin polymeric films indicate that no spontaneous formation of hydroxide ion bridged porphyrin dimers occurs in the membrane plasticized both with high or low dielectric constant plasticizer, due to a low oxophilicity of central Pt. The computational study of various anion-Pt(IV)TPPCl(2) complex formation by means of semi-empirical and density functional theory (DFT) methods revealed a good correlation between calculated and measured ionophore selectivity.

Porphyrin diad 1 was synthesized by reaction of the acyl chloride of porphyrin 2 and trans-1,2-dithiane-4,5-diol. The Co complex of this diad was studied as a potential enantioselective receptor for chiral recognition in solution and in the solid state. In solution both enantiomers of limonene induce significant changes in the visible and circular dichroism (CD) spectra of [Co2(1)], while a different behavior is observed in the case of the enantiomeric pair of trans-1,2-diaminocyclohexane. A different efficiency of [Co2(1)] chiral recognition is obtained for these compounds, with a remarkable degree of enantiodiscrimination observed in the case of limonene. Self-assembled monolayers of [Co2(1)] were deposited onto the gold electrodes of quartz crystal microbalances to be used as sensing materials of nanogravimetric sensors operating in the gas phase. The enantiodiscrimination properties of these sensors towards the enantiomeric pairs of chiral analytes have been studied. While in the case of analytes bearing donor ligand atoms we did not observe a remarkable enantioselectivity, a significant degree of chiral discrimination was observed in the case of limonene; this result is particularly encouraging for the potential development of enantioselective chemical sensors for use in an array configuration.