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Five- and six-membered heterocycles containing nitrogen or oxygen have been considered as privileged scaffolds in organic chemistry and the chemical industry because of their usage in high-value commodities. Herein, we report a two-dimensional (2D) Cu(II)-based MOF catalyst, IITKGP-40,via the strategic employment of ample Lewis acid–base bifunctional sites (open metal nodes and free pyrazine moieties) along the pore wall. IITKGP-40could convert toxic CO2to cyclic carbonates in an atom-economical manner under solvent-free conditions and aromatic aldehyde to bioactive 1,4-DHPs via Hantzsch condensation. Exceptional catalytic performance (99%) and turnover number under mild reaction conditions for CO2fixation using sterically hindered styrene oxide, and good-to-excellent yields for a wide range of aromatic aldehydes toward 1,4-dihydropyridines (1,4-DHPs) make IITKGP-40promising as a multipurpose heterogeneous catalyst. Moreover, to demonstrate the practical utility of the catalyst, two biologically important drug molecules, diludine and nitrendipine analogue, have also been synthesized. IITKGP-40is recyclable for at least three consecutive runs without significant loss of activity, making it promising for real-time applications.

The effect of nonstoichiometry on the cation distribution, crystal structure, and magnetic properties of a series of Cr-rich Sr2Cr1+xRe1–xO6samples has been investigated. The double perovskite structure is maintained over a wide solid solution range that extends from x = 0 to approximately x = 0.5. For most of the solid solution range, the Cr-rich octahedral site maintains a nearly constant occupancy, 87% Cr and 13% Re, that is comparable to prior studies of Sr2CrReO6, while Cr steadily replaces Re on the other octahedral site. As x approaches 0.5, long-range Cr/Re ordering drops precipitously. Analysis of X-ray powder diffraction peak shapes reveals antiphase boundaries, associated with Cr/Re ordering, the concentration of which increases steadily with increasing x. Neutron powder diffraction studies confirm antiferromagnetic coupling between antisite Cr3+ions and Cr3+ions that occupy the normal sites, leading to site-dependent ferrimagnetic ordering. Density functional theory calculations indicate that chromium maintains a +3 oxidation state across the series, while the oxidation state of rhenium increases with increasing x. Calculations are also used to explore the energies of competing magnetic ground states. Except for the most chromium-rich compositions (x ≈ 0.5), site-dependent ferrimagnetism is retained with only a modest reduction in TC. The saturation magnetization steadily decreases as the chromium content increases due to a combination of Cr/Re antisite disorder and antiphase boundaries.

The ternary phase with the composition Ni3InSb has been synthesized by high-temperature synthesis and structurally characterized by a combination of X-ray analysis, neutron diffraction analysis, and theoretical calculations. The structure of Ni3InSb crystallizes in the orthorhombic space group Pnmawith lattice constants a= 7.111(3) Å, b= 5.193(3) Å, and c= 8.2113(2) Å. The crystal structure contains ∼20 atoms in its unit cell, which are distributed over four crystallographically independent positions (two Ni, one In, and one Sb). The crystal structure can be considered as a ternary substitutional variant of Ni3Sn2(Pnma, no. 62), where a trivalent In and a pentavalent Sb orderly occupy two tetravalent Sn sites of Ni3Sn2. This site decoration pattern of two neighboring elements, In and Sb, is unique and confirmed by first principles total energy calculations. The crystal structure can be described by two building units: Ni2Sb (building unit of Ni2In) and NiIn (NiAs-type). They alternate in the crystal structure and form infinite ac-slabs (puckered), and the slabs are stacked along [010]. A triangular lattice formed by Ni atoms indicates the existence of a geometrically frustrated structure. The calculated density of states and crystal orbital Hamilton population enlighten the stability and bonding characteristics of the structure. The temperature-dependent neutron diffraction study down to 5 K reveals that the crystal structure remains in the same orthorhombic symmetry with a weak anomaly in the lattice parameters at ∼100 K. Detailed temperature- and magnetic field-dependent magnetic properties of the title phase Ni3InSb show spin-glass- or spin-disorder-like behaviors below ∼300 K with an unusual magnetic behavior below 100 K, where an enhancement of magnetization with a decrease of the coercive field has been found.

Trivalent metal ions (Cr3+, Al3+, and Fe3+) constitute a major section of the environmental pollutants, and their excess accumulation has a detrimental effect on health, so their detection in trace quantity has been a hot topic of research. A highly scalable 3D porous Zn-based luminescent metal–organic framework (MOF) has been synthesized by exploiting the mixed ligand synthesis concept. The strategic selection of an aromatic π-conjugated organic linker and N-rich spacer containing the azine functionality as metal ion binding sites immobilized across the pore spaces, have made this MOF an ideal turn-on sensor for Al3+, Cr3+, and Fe3+ions with very high sensitivity, selectivity, and recyclability. An in-depth study revealed absorbance caused enhancement mechanism (ACE) responsible for such turn-on phenomena. In order to make the detection process straightforward, convenient, portable, and economically viable, we have fabricated MOF test paper strips (the MOF could be simply immobilized onto the paper strips) for naked eye visual detection under UV light, which, thus, manifests its potential as a real-time smart sensor for these trivalent ions.

Metal–ligand coordination interactions are usually much stronger than weak intermolecular interactions. Nevertheless, here, we show experimental evidence and theoretical confirmation of a very rare example where metal–ligand bonds dissociate in an irreversible way, helped by a large number of weak intermolecular interactions that surpass the energy of the metal–ligand bond. Thus, we describe the design and synthesis of trinuclear Mn2Fe complex {[Mn(L)(H2O)]2Fe(CN)6},2–starting from a mononuclear Mn(III)-Schiff base complex: [Mn(L)(H2O)Cl] (1) and [Fe(CN)6]4–anions. This reaction implies the dissociation of Mn(III)-Cl coordination bonds and the formation of Mn(III)-NC bonds with the help of several intermolecular interactions. Here, we present the synthesis, crystal structure, and magnetic characterization of the monomeric Mn(III) complex [Mn(L)(H2O)Cl] (1) and of compound (H3O)[Mn(L)(H2O)2]{[Mn(L)(H2O)]2Fe(CN)6}·4H2O (2) (H2L = 2,2′-((1E,1′E)-(ethane-1,2-diylbis(azaneylylidene))bis(methaneylylidene))bis(4-methoxyphenol)). Complex 1is a monomer where the Schiff base ligand (L) is coordinated to the four equatorial positions of the Mn(III) center with a H2O molecule and a Cl–ion at the axial sites and the monomeric units are assembled by π–π and hydrogen-bonding interactions to build supramolecular dimers. The combination of [Fe(CN)6]4–with complex 1leads to the formation of linear Mn-NC-Fe-CN-Mn trimers where two transcyano groups of the [Fe(CN)6]4–anion replace the labile chloride from the coordination sphere of two [Mn(L)(H2O)Cl] complexes, giving rise to the linear anionic {[Mn(L)(H2O)]2Fe(CN)6}2–trimer. This Mn2Fe trimer crystallizes with an oxonium cation and a mononuclear [Mn(L)(H2O)2]+cation, closely related to the precursor neutral complex [Mn(L)(H2O)Cl]. In compound 2, the Mn2Fe trimers are assembled by several hydrogen-bonding and π–π interactions to frame an extended structure similar to that of complex 1. Density functional theoretical (DFT) calculations at the PBE1PBE-D3/def2-TZVP level show that the bond dissociation energy (−29.3 kcal/mol) for the Mn(III)-Cl bond is smaller than the summation of all the weak intermolecular interactions (−30.1 kcal/mol). Variable-temperature magnetic studies imply the existence of weak intermolecular antiferromagnetic couplings in both compounds, which can be can cancelled with a critical field of ca. 2.0 and 2.5 T at 2 K for compounds 1and 2, respectively. The magnetic properties of compound 1have been fit with a simple S= 2 monomer with g= 1.959, a weak zero-field splitting (|D| = 1.23 cm–1), and a very weak intermolecular interaction (zJ= −0.03 cm–1). For compound 2, we have used a model with an S= 2 monomer with ZFS plus an S= 2 antiferromagnetically coupled dimer with g= 2.009, |D| = 1.21 cm–1, and J= −0.42 cm–1. The metamagnetic behavior of both compounds is attributed to the weak intermolecular π–π and hydrogen-bonding interactions.

The work represents a rare example of an aza-crown-based macrocyclic chemosensor, H2DTC(H2DTC= 1,16-dihydroxy-tetraaza-30-crown-8) for the selective detection of both Zn2+and Cu2+in HEPES buffer medium (pH 7.4). H2DTCexhibits a fluorescence response for both Zn2+and Cu2+ions. The reversibility of the chemosensor in its binding with Zn2+and Cu2+ions is also examined using a Na2EDTA solution. H2DTCexhibits a chelation-enhanced fluorescence (CHEF) effect in the presence of Zn2+ions and a quenching effect (CHEQ) in the presence of paramagnetic Cu2+ions. Furthermore, the geometry and spectral properties of H2DTCand the chemosensor bound to Zn2+have been studied by DFT and TDDFT calculations. The limit of detection (LOD) values are 0.11 × 10–9and 0.27 × 10–9M for Cu2+and Zn2+, respectively. The formation constants for the Zn2+and Cu2+complexes have been measured by pH-potentiometry in 0.15 M NaCl in 70:30 (v:v) water:ethanol at 298.1 K. UV–vis absorption and fluorometric spectral data and pH-potentiometric titrations indicate 1:1 and 2:1 metal:chemosensor species. In the solid state H2DTCis able to accommodate up to four metal ions, as proved by the crystal structures of the complexes [Zn4(DTC)(OH)2(NO3)4] (1) and {[Cu4(DTC)(OCH3)2(NO3)4]·H2O}n(2). H2DTCcan be used as a potential chemosensor for monitoring Zn2+and Cu2+ions in biological and environmental media with outstanding accuracy and precision. The propensity of H2DTCto detect intracellular Cu2+and Zn2+ions in the triple negative human breast cancer cell line MDA-MB-468 and in HeLa cells has been determined by fluorescence cell imaging.

The present work is part of our ongoing quest for developing functional inorganic complexes using unorthodox pyridyl–pyrazolyl-based ligands. Accordingly, we report herein the synthesis, characterization, and luminescence and magnetic properties of four 3d–4f mixed-metal complexes with a general core of Ln2Zn6(Ln = Dy, Gd, Tb, and Eu). In stark contrast to the popular wisdom of using a compartmental ligand with separate islands of hardand softcoordinating sites for selective coordination, we have vindicated our approach of using a ligand with overcrowded N-coordinating sites that show equal efficiency with both 4f and 3d metals toward multinuclear cage-cluster formation. The encouraging red and green photolumiscent features of noncytotoxic Eu2Zn6and Tb2Zn6complexes along with their existence in nanoscale dimension have been exploited with live-cell confocal microscopy imaging of human breast adenocarcinoma (MCF7) cells. The magnetic features of the Dy2Zn6complex confirm the single-molecule-magnet behavior with befitting frequency- and temperature-dependent out-of-phase signals along with an Ueffvalue of ∼5 K and a relaxation time of 8.52 × 10–6s. The Gd2Zn6complex, on the other hand, shows cryogenic magnetic refrigeration with an entropy change of 11.25 J kg–1K–1at a magnetic field of 7 T and at 2 K. Another important aspect of this work reflects the excellent agreement between the experimental results and theoretical calculations. The theoretical studies carried out using the broken-symmetry density functional theory, ORCAsuite of programs, and MOLCAScalculations using the complete-active-space self-consistent-field method show an excellent synergism with the experimentally measured magnetic and spectroscopic data.

A variety of heme derivatives are pervasive in nature, having different architectures that are complementary to their function. Herein, we report the synthesis of a series of iron porphyrinoids, which bear electron-withdrawing groups and/or are saturated at the β-pyrrolic position, mimicking the structural variation of naturally occurring hemes. The effects of the aforementioned factors were systematically studied using a combination of electrochemistry, spectroscopy, and theoretical calculations with the carbon monoxide (CO) and nitric oxide (NO) adducts of these iron porphyinoids. The reduction potentials of iron porphyrinoids vary over several hundreds of millivolts, and the X–O (X = C, N) vibrations of the adducts vary over 10–15 cm–1. Density functional theory calculations indicate that the presence of electron-withdrawing groups and saturation of the pyrrole ring lowers the π*-acceptor orbital energies of the macrocycle, which, in turn, attenuates the bonding of iron to CO and NO. A hypothesis has been presented as to why cytochrome ccontaining nitrite reductases and cytochrome cd1containing nitrite reductases follow different mechanistic pathways of nitrite reduction. This study also helps to rationalize the choice of heme a3and not the most abundant heme bcofactor in cytochrome coxidase.

We present a bifunctional heptanuclear cobalt(II)/cobalt(III) molecular complex formulated as [Co7(μ3–OH)4(H2L1)2(HL2)2](NO3)6·6H2O (1) (where H5L1is 2,2′-(((1E,1′E)-((2-hydroxy-5-methyl-1,3-phenylene)bis(methanylylidene))bis(azanylylidene))bis(propane-1,3-diol)) and H2L2is 2-amino-1,3-propanediol). Compound 1has been characterized by single-crystal X-ray diffraction analysis along with other spectral and magnetic measurements. Structural analysis indicates that 1contains a mixed-valence Co7cluster where a central Co(II) ion is connected to six different Co centers (four CoIIIand two CoIIions) by four μ3–OH groups, giving rise to a planar heptanuclear cluster that resembles a molecular fragment of a layered double hydroxide (LDH). Two triply deprotonated (H2L1)3–ligands form the outer side of the cluster while two singly deprotonated (HL2)−ligands are located at the top and bottom of the central heptanuclear core. Variable temperature magnetic measurements indicate the presence of weak ferromagnetic CoII···CoIIinteractions (J= 3.53(6) cm–1) within the linear trinuclear CoIIcluster. AC susceptibility measurements show that 1is a field-induced single-molecule magnet (SMM) with τ0= 8.2(7) × 10–7s and Ueff= 11.3(4) K. The electrocatalytic hydrogen evolution reaction (HER) activity of 1in homogeneous phase shows an overpotential of 455 mV, with a Faradaic efficiency of 81% and a TOF of 8.97 × 104μmol H2h–1mol–1.

Altering the morphology of electrochemically active nanostructured materials could fundamentally influence their subsequent catalytic as well as oxygen evolution reaction (OER) performance. Enhanced OER activity for mixed-metal spinel-type sulfide (CuCo2S4) nanorods is generally done by blending the material that has high conductive supports together with those having a high surface volume ratio, for example, graphitic carbon nitrides (g-C3N4). Here, we report a noble-metal-free CuCo2S4nanorod-based electrocatalyst appropriate for basic OER and neutral media, through a simple one-step thermal decomposition approach from its molecular precursors pyrrolidine dithiocarbamate-copper(II), Cu[PDTC]2, and pyrrolidine dithiocarbamate-cobalt(II), Co[PDTC]2complexes. Transmission electron microscopy (TEM) images as well as X-ray diffraction (XRD) patterns suggest that as-synthesized CuCo2S4nanorods are highly crystalline in nature and are connected on the g-C3N4support. Attenuated total reflectance–Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy studies affirm the successful formation of bonds that bridge (Co–N/S–C) at the interface of CuCo2S4nanorods and g-C3N4. The kinetics of the reaction are expedited, as these bridging bonds function as an electron transport chain, empowering OER electrocatalytically under a low overpotential (242 mV) of a current density at 10 mA cm–2under basic conditions, resulting in very high durability. Moreover, CuCo2S4/g-C3N4composite nanorods exhibit a high catalytic activity of OER under a neutral medium at an overpotential of 406 mV and a current density of 10 mA cm–2.

Bi2WO6nanocrystals exhibit excellent photocatalytic properties in the visible range of the solar spectrum, and intense efforts are directed at designing effective synthesis processes with control of size, morphology, and hierarchical structure. All known hydrothermal syntheses produce either nanoplatelet morphology or hierarchical structures based on such primary entities. Here we investigate the nucleation and growth of Bi2WO6nanocrystals under hydrothermal conditions using in situX-ray total scattering (TS) and powder X-ray diffraction (PXRD) measurements. It is shown that the preferential growth of Bi2WO6nanoplates is due to the presence of disordered layers of Bi2O22+molecular complexes in the precursor solution with an approximate length of 13 Å. These layers interact with tetrahedral WO42–molecular units and eventually form the disordered cubic (Bi0.933W0.067)O1.6) crystalline phase. When enough tungsten units are intertwined between Bi2O22+layers formation of Bi2WO6pristine nanoplates takes place by necessary sideways addition of units in the acplane. The experimentally observed formation mechanism suggests that the Bi/W atomic ratio must play a central role in the nucleation (assembly of initial crystal layers). Indeed, it is observed in separate continuous flow supercritical synthesis that for a stoichiometric (Bi/W = 2:1) precursor, a (Bi0.933W0.067)O1.6) impurity phase is always observed together with the main Bi2WO6product. Excess tungsten is required in the precursor to form phase-pure Bi2WO6material. Thus, the present study also reports a fast, scalable, and green method for production of this highly attractive photocatalyst.

A series of 1:1 sandwichcomplexes consisting of chiral zinc(II) bisporphyrin hosts and a series of chiral guests has been synthesized and has rationalized the underpinning mechanism of chirality transfer in the host–guest supramolecular assemblies. The number of stereogenic centers is also varied in both the host and guests, which provides insight into the overall helicity of the assembly. The interactions between the chiral host and chiral guests have been investigated by UV–visible, CD, and 1H NMR spectroscopic titrations along with extensive DFT studies. Interestingly, CD spectral changes are very different between chiral guests with one and two chiral centers. It has been observed that the sign of the CD couplet of the host–guest complexes is dictated by the chirality of the host only with guests having one chiral center. The match and mismatch of the chirality of the guest only affects the amplitude of the CD signal; the sign, however, remains intact. In sharp contrast, the helicity of the 1:1 sandwichcomplex is dictated by the chirality of the guests having two chiral centers. However, amplification of the CD couplet is observed upon matching of the chirality between the host and guest, while a mismatch leads to an inversion of the CD couplet. The enantiomeric host also displays similar trends with chiral guests but with opposite sign. The enantioselective host also displays excellent chiral discrimination ability toward enantiomeric guests with two chiral centers. The guest with the same chirality as the host binds much stronger as compared to its enantiomer. Remarkable enantiodiscrimination effects were also detected in the 1H NMR spectra of the diastereomeric complexes in which well-resolved separation of the signals is clearly visible. The theoretical calculations are consistent with those of the experiment.

Two azo functionalized Zn(II)-based MOFs, {[Zn(SDB)(3,3′-L)0.5]·xG}n, IITKGP-13A, and {[Zn2(SDB)2(4,4′-L)]·xG}n, IITKGP-13B (IITKGP stands for Indian Institute of Technology Kharagpur), have been constructed through the self-assembly of isomeric N,N′-donor spacers (3,3′-L = 3,3′-azobispyridine and 4,4′-L = 4,4′-azobispyridine) with organic ligand 4,4′-sulfonyldibenzoic acid (SDBH2) and Zn(NO3)2·6H2O (G represents disordered solvent molecules). Single-crystal X-ray diffraction studies reveal the 2D structure with sqltopology for both MOFs. However, the subtle change in positions of coordinating N atoms of spacers makes IITKGP-13A noninterpenetrated, while IITKGP-13B bears a 2-fold interpenetrated structure. IITKGP-13A exhibits higher uptake of CO2over CH4and N2with high IAST selectivities for mixed CO2/CH4(50:50, biogas) and CO2/N2(15:85, flue gas) gas systems. In contrast, IITKGP-13B takes up very low amount of CO2gas (0.4 mmol g−1) compared to IITKGP-13A (1.65 mmol g−1) at 295 K. Density functional theory (DFT)-based electronic structure calculations have been performed to explain the origin of the large differences in CO2uptake capacity between the two MOFs at the atomistic level. The results show that the value of the change in enthalpy (ΔH) at 298 K temperature and 1 bar pressure for the CO2adsorption is more negative in IITKGP-13A as compared to that in IITKGP-13B, thus indicating that CO2molecules are more favored to get adsorbed in IITKGP-13A than in IITKGP-13B. The computed values for the Gibbs’ free energy change (ΔG) for the CO2adsorption are positive for both of the MOFs, but a higher value is observed for the IITKGP-13B. The noncovalent types of interactions are the main contribution toward the attractive energies between the host MOF frameworks and guest CO2molecules, which has been studied with the help of energy decomposition analysis (EDA).

Solid electrolytes have regained tremendous interest recently in light of the exposed vulnerability of current rechargeable battery technologies. While designing solid electrolytes, most efforts concentrated on creating structural disorder (vacancies, interstitials, etc.) in a cationic Li/Na sublattice to increase ionic conductivity. In phosphates, the ionic conductivity can also be increased by rotational disorder in the anionic sublattice, via a paddle-wheel mechanism. Herein, we report on Na4Zn(PO4)2which is designed from Na3PO4, replacing Na+with Zn2+and introducing a vacancy for charge balance. We show that Na4Zn(PO4)2undergoes a series of structural transitions under temperature, which are associated with an increase in ionic conductivity by several orders of magnitude. Our detailed crystallographic study, combining electron, neutron, and X-ray powder diffraction, reveals that the room-temperature form, α-Na4Zn(PO4)2, contains orientationally ordered PO4groups, which undergo partial and full rotational disorder in the high-temperature β- and γ-polymorphs, respectively. We furthermore showed that the highly conducting γ-polymorph could be stabilized at room temperature by ball-milling, whereas the β-polymorph can be stabilized by partial substitution of Zn2+with Ga3+and Al3+. These findings emphasize the role of rotational disorder as an extra parameter to design new solid electrolytes.

The chemical and electrochemical reduction of CO2to value added chemicals entails the development of efficient and selective catalysts. Synthesis, characterization and electrochemical CO2reduction activity of a air-stable cobalt(III) diphenylphosphenethano-bis(2-pyridinethiolate)chloride [{Co(dppe)(2-PyS)2}Cl, 1-Cl] complex is divulged. The complex reduces CO2under homogeneous electrocatalytic conditions to produce CO with high Faradaic efficiency (FE > 92%) and selectivity in the presence of water. Through detailed electrochemical investigations, product analysis, and mechanistic investigations supported by theoretical calculations, it is established that complex 1-Clreduces CO2in its Co(I) state. A reductive cleavage leads to a dangling protonated pyridine arm which enables facile CO2binding through a H-bond donation and facilitates the C–O bond cleavage via a directed protonation. A systematic benchmarking of this catalyst indicates that it has a modest overpotential (∼180 mV) and a TOF of ∼20 s–1for selective reduction of CO2to CO with H2O as a proton source.

Control over the stimuli-responsive behavior of smart molecular systems can influence their capability to execute complex functionalities. Herein, we report the development of a suite of spiropyran-based multi-stimuli-responsive self-assembled platinum(II) macrocycles (5–7), rendering coordination-assisted enhanced photochromism relative to the corresponding ligands. 5showed shrinking and swelling during photoreversal, while 6and 7are fast and fatigue-free supramolecular photoswitches. 6turns out to be a better fatigue-resistant photoswitch and can retain an intact photoswitching ability of up to 20 reversible cycles. The switching behavior of the macrocycles can also be precisely controlled by tuning the pH of the medium. Our present strategy for the construction of rapid stimuli-responsive supramolecular architectures via coordination-driven self-assembly represents an efficient route for the development of smart molecular switches.

Two Cu(II)-based metal–organic frameworks (MOFs) having paddle-wheel secondary building units (SBUs), namely, 1Meand 1ipr, were synthesized solvothermally using two new bent di-isophthalate ligands incorporating different substituents. The MOFs showed high porosity (BET surface area, 2191 m2/g for 1Meand 1402 m2/g for 1ipr). For 1Me, very high CO2adsorption (98.5 wt % at 195 K, 42.9 wt % at 273 K, 23.3 wt % at 298 K) at 1 bar was found, while for 1ipr,it was significantly less (14.3 wt % at 298 K and 1 bar, 54.4 wt % at 298 K at 50 bar). 1Meexhibited H2uptake of 3.2 wt % at 77 K and 1 bar of pressure, which compares well with other benchmark MOFs. For 1ipr, the H2uptake was found to be 2.54 wt % under similar experimental conditions. The significant adsorption of H2and CO2for 1Mecould be due to the presence of micropores as well as unsaturated metal sites in these MOFs besides the presence of substituents that interact with the gas molecules. The experimental adsorption behavior of the MOFs could be justified by theoretical calculations. Additionally, catalytic conversions of CO2and CS2into useful chemicals like cyclic carbonates, cyclic trithiocarbonates, and cyclic dithiocarbonates could be achieved.

A clear and unambiguous rationalization of chirality induction, amplification, and subsequent inversion processes has been demonstrated using an achiral Mg(II)porphyrin dimer (host) and a series of chiral diols (guests) upon stepwise formation of a 1:1 host–guest polymer and 1:2 host–guest monomer via intermolecular assembling and disassembling processes. Crystallographic characterizations are reported here for both the polymer and the monomeric complexes, which enable us to completely scrutinize the structural and geometrical changes systematically in rationalizing their optical properties. The sign of the CD couplets for both the polymer and monomer are just opposite between Rand Sguests, which suggests that the chirality is dictated solely by the stereogenic projection of the chiral centers. Stronger intra- and intermolecular coupling in the polymeric complexes is responsible for the highly enhanced CD couplets as compared to the monomer and have only intramolecular coupling as also observed in their X-ray structures. DFT studies clearly support the experimental observations.