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Boro rice, an emerging low-risk crop variety of rice, cultivated using residual or stored water after Kharif season. To enhance the quality and production of rice, potassium (K) and phosphorus (P) are the common constituents of agricultural fertilizers. However, excess application of fertilizers causes leaching of nutrients and contaminates the groundwater system. Therefore, assessment and optimization of fertilizer dose are needed for better management of fertilizers. Towards this, the present study determines the path, persistence, and mobility of K and P under the Boro rice cropping system. The experimental site consisted of four plots having Boro rice with four different fertilizer doses of nitrogen (N), P, K viz. 100%, 75%, 50%, and 25% of the recommended dose. Disturbed soil samples were analysed for K and P from pre-sown land to tillering stage at 0–5, 5–10, 10–15, 15–30, 30–45, and 45–60 cm depths. Simultaneously, K and available P were also simulated in the subsurface soil layers through the HYDRUS-1D model. The statistical comparisons were made with RMSER, E, and PBIAS between the modelled values and laboratory-measured values. Although, the results showed that all the treatments considered had agreeable simulations for both K and P, the K simulations were found to be better as compared to P simulations except for 25% where P simulations outperformed K. The simulated concentration at all doses was found most appropriate when measured for the subsurface layers (up to 45 cm), while showed an underestimation in the bottom layers (45–60 cm) of soil.

A field trial comprising three levels of zinc (Zn) 0, 5 and 10 kg ha-1, three levels of iron (Fe) 0, 15 and 30 kg ha-1 and three levels of manganese (Mn) 0, 5 and 10 kg ha-1 was carried out during ...

A field trial comprising of 3 levels of Zn-0, 5 and 10 kg ha-1, 3 levels of Fe-0, 15 and 30 kg ha-1 and 3 levels of Mn-0, 5 and 10 kg ha-1 was carried out during the two consecutive rainy seasons of 2008 and 2009 to study their effect on growth, yield and quality of aromatic rice cv. HUBR 2-1. The experiment was conducted in 33 partial confounding with three replications. All the micronutrients (Zn, Fe and Mn) were applied as basal and rest half doses were applied through foliar application at different intervals of crop growth. Application of 10 kg Zn ha-1 recorded significantly higher growth attributes i.e. plant height, tiller hill-1, dry weight and leaf area index (LAI) as compared to preceding doses. Significant increase in growth attributes was also observed with the application of 15 kg Fe ha-1, but it was statistically similar to 30 kg Fe ha-1. Similarly, incorporation of 5 kg Mn ha-1 significantly increased the growth attributes of rice but further increase in Mn levels decreased the response. Application of 10 kg Zn ha-1 (51.33 q ha-1) and 15 kg Fe ha-1 (51.09 q ha-1) resulted in significantly higher grain yield over control. Whereas, application of 5 kg Mn ha-1 produced the highest grain yield (49.91 q ha-1), but was at par with 10 kg Mn ha-1 (49.18 q ha-1).In respect of quality traits, application of 10 kg Zn ha-1 and 15 kg Fe ha-1 recorded maximum values of hulling, milling, head rice recovery, kernel length and breadth, which remained significantly superior to rest of the doses. Hence, to achieve the maximum productivity, profitability, as well as, quality of aromatic rice cv. HUBR 2-1 was grown with application of 10 kg Zn and 15 kg Fe along with 5 kg Mn ha-1.

Profiling a potential energy surface (PES), all the way to dissociate a molecular state into particular fragments and to display real or avoided crossings, requires a multireference description and the maintenance of size-consistency. The many body methods, which suit this purpose, should thus be size-extensive. Size-extensive theories, which are invariant with respect to transformation among active orbitals are, in principle, size-consistent. Relatively cheaper size-extensive theories, which do not possess this invariance, can still be size-consistent if the active orbitals are localized on the asymptotic fragments. Such methods, if perturbative in nature, require the use of an unperturbed Hamiltonian, which has orbital invariance with respect to the transformation within active, core, and virtual orbitals. The principal focus of this paper is to numerically realize size-consistency with localized active orbitals using our recently developed orbitally noninvariant Unitary Group Adapted State Specific Multireference second order Perturbation Theory (UGA-SSMRPT2) as a prototype method. Our findings expose certain generic potential pitfalls of size-extensive but orbitally noninvariant MRPT theories, which are mostly related to the inability of reaching proper localized active orbitals in the fragments due to the artifacts of the orbital generation procedure. Despite the invariance of the zeroth order CAS function, lack of invariance of the MRPT itself then leads to size-inconsistency. In particular, reaching symmetry broken fragment active orbitals is an issue of concern where suitable state-averaging might ameliorate the problem, but then one has to abandon full orbital optimization. Additionally, there can be situations where the orbitals of the fragment reached as an asymptote of the supermolecule are not the same as those obtained from the optimization of the fragments individually and will require additional transformation. Moreover, for a certain PES, one may either abandon the use of optimized orbitals for that state to preserve proper symmetry and degeneracy in the fragment orbitals or be satisfied with the use of optimized orbitals, which generate broken symmetric orbitals in the fragmentation limit. All these pathologies are illustrated using the PES of various electronic states of multiply bonded systems like N2, C2H2, HCN, C2, and O2. Subject to such proviso, the UGA-SSMRPT2 turns out to be an excellent theory for studying the PES leading to fragmentation of strongly correlated systems satisfying the requirements of size-consistency with localized active orbitals. An unexpected spin-off of our studies is the realization that the size-inextensive MRMP2, which bears a close structural similarity with our theory, might under certain situations display size-consistency. We analyze this feature concretely in our paper. Our studies may serve as a benchmark for monitoring numerically the size-consistency of any state specific multireference theory which is size-extensive but not invariant with respect to transformation of active orbitals.

A field trial consisting of four granule formulation doses and five liquid formulation sprays of a seaweed extract from Ascophyllum nodosum commercially known as Biovita, along with the recommended dose of nitrogen (N)–phosphorus (P)–potassium (K), was conducted during 2008 and 2009 in BHU, Varanasi, India, to evaluate its effect on wheat (var. HUW 468) under a no-tillage system. Among the granule doses, the 10 kg ha−1 basal application and the two liquid sprays of 500 cm3 ha−1 each at 25 and 50 days after sowing significantly improved the performance of wheat. On an average under these two treatments, the greatest grain and straw yields were observed were 3454.5, 3446.5 and 5187.5, 5220.0 kg ha−1, respectively. The greatest protein content was found when further high doses of extract were applied. A faster decomposition of the paddy residue was also observed as indicated by an earlier decline in carbon (C)/N ratio of the soil in the treated plots.

A highly sensitive nitrogen dioxide (NO2) sensor based on orientational transition of a thin film of liquid crystal (LC) supported on a gold surface is reported. Transport of NO2 molecules through the LC film to the LC-gold interface induces an orientation transition in the LC film. The dynamic behavior of the sensor response exhibits a concentration-dependent response rate that is employed to generate an algorithm for quantitative determination of unknown concentrations. Sensitive, selective and reversible detection with minimal effects of environmental fluctuations suggest that these sensors can be used for quantitative NO2 detection for a number of applications.

The performance characteristics of liquid crystal (LC)-based sensors for detection of dimethylmethylphosphonate (DMMP), a representative organophosphonate compound and simulant of chemical warfare agent sarin, are presented. The equilibration coordination interaction among the aluminum ions on a surface, the cyano group in LCs, and the phosphoryl group in DMMP have been exploited to achieve sensitive, fast, and reversible sensor responses. Measurement of the response time of the sensor allows quantitative detection of an unknown concentration of DMMP with high accuracy. The strong coordination interaction between the cyano group present in the LC and the aluminum ions supporting the film of LC provides immunity to exposure to a number of potentially interfering compounds including high humidity. Exposure studies under varied temperature and humid conditions show a minimal effect on the sensor performance. Although the sensors stored at room temperature exhibited slightly diminished sensitivity, the sensors stored at 4 °C remained functionally stable for at least six months. These results combined with the ease of fabrication using the established processes, low cost associated with off-the-shelf components, and small foot print suggest that these LC-based sensors can form the basis of a new class of low cost, light weight, robust sensors for a number of detection applications.

Rapid identification of both species and even specific strains of human pathogenic bacteria grown on standard agar has been achieved from the volatiles they produce using a disposable colorimetric sensor array in a Petri dish imaged with an inexpensive scanner. All 10 strains of bacteria tested, including Enterococcus faecalis and Staphylococcus aureus and their antibiotic-resistant forms, were identified with 98.8% accuracy within 10 h, a clinically important time frame. Furthermore, the colorimetric sensor arrays also proved useful as a simple research tool for the study of bacterial metabolism and as an easy method for the optimization of bacterial production of fine chemicals or other fermentation processes.

This paper reports the results of a systematic investigation of factors that determine the alignment of nematic liquid crystals (NLCs) on inorganic salt decorated surfaces used in NLC-based gas sensors. When surfaces functionalised with different self-assembled monolayers (SAMs) possessing a variety of terminal groups are treated with coordinating metal salts, the resultant homeotropic alignment (i.e. alignment perpendicular to the surface) of NLC on these surfaces remains stable for an extended time and is independent of the functional group on the SAM. Liquid crystal alignment studies on surfaces treated with different metal ions reveal that the forces originating from coordination and non-coordination interactions are involved in promoting the homeotropic alignment of NLCs in these systems. The homeotropic alignment in these systems is unaffected by the presence of water. These results combined together, suggest that with a precise control of the alignment of NLC at the metal–NLC interfaces, these inte...

A field trial comprising 3 rice varieties (NDR-359, Sarju 52, HUBR 2-1) and 4 LCC scores (≤ 2, ≤ 3, ≤ 4, ≤ 5) along with the recommended dose of N was conducted in a split plot design to calibrate the LCC for nitrogen requirement of rice. Maximum grain yields of NDR-359, Sarju 52 at LCC ≤ 5 and HUBR 2-1 at LCC ≤ 4 were found to be 47.10, 40.66 and 36.04 q/ha respectively. The critical LCC score for real time nitrogen requirement for NDR 359 and Sarju 52 was found to be ≤ 5, while for HUBR 2-1 it was ≤ 4. Agronomic and recovery efficiency of nitrogen also followed the same trend. In the functional relationship between SPAD value and LCC score, while it was linear in NDR-359 and Sarju 52, for HUBR 2-1 it was quadratic. Further a positive correlation between SPAD values and LCC score was observed in all the 3 varieties.

Parity Non Conservation (PNC) in atomic systems can be observed in experiments using a single trapped ion and intense laser fields. The original proposal is based on a single barium ion. Here, we study the feasibility for carrying out similar experiment with a single radium ion. Since the PNC effect in atomic system increases faster than the Z3, where Z is the atomic number, radium is a natural choice. The advantages and disadvantages of measuring atomic parity violation in radium ion are discussed.

A field trial was conducted during the kharif (rainy) seasons of 2002 and 2003 at the Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India. The trial was carried out to study the effect of planting methods, sources and levels of nitrogen on soil properties, yield and NPK uptake by rice ( Oryza sativa L.) under direct seeded condition. Planting methods significantly influenced the physical, chemical and biological properties of soil. Bulk density (1.385 g cm −3 ), organic carbon (0.43%) and soil moisture content (15.46%) were higher in zero till seeding plots than rotavator and conventional seeding. However, infiltration rate, soil temperature, pH and electrical conductivity showed a declining trend under this treatment and were found maximum (11.54 mm h −1 , 36.21 °C at 55 DAS, 30.65 °C at harvest, 7.59 and 0.47 ds m −1 ) with conventional seeding. The maximum population of bacteria (25.60 × 10 5 ), fungi (14.26 × 10 4 ) and azotobactor (10.19 × 10 3 ) were found in the plot with zero till seeding while in case of actinomycetes the highest population (25.61 × 10 5 ) was found in conventional seeding. Nitrogen sources as well as levels failed to bring about any significant change in the soil properties. The highest grain (3825 kg ha −1 ) and straw yields (5446 kg ha −1 ) and N, P, K uptake were recorded in conventional seeding and were found significantly superior to zero till seeding (3144 kg ha −1 ) but it remained at par with rotavator seeding (3585 kg ha −1 ). Among the nitrogen sources, neem ( Azadirachta indica ) coated urea produced significantly higher grain (3761 kg ha −1 ) and straw yields (5396 kg ha −1 ) with greater NPK uptake than prilled urea and prilled urea + spent mentha. (The distillation waste of mint ( Mentha arvensis ) herbage is known as spent mentha.) Application of 150 kg N ha −1 produced maximum grain (3828 kg ha −1 ) and straw yields (5460 kg ha −1 ) although it remained at par with 100 kg N ha −1 (3738 and 5393 kg ha −1 ).

A simple, rapid and low-cost method for differentiating a wide range of concentrations of gaseous hydrogen sulfide (H 2 S) is described. A large dynamic range (50 ppb to 50 ppm) was successfully classified at ambient temperature using a colorimetric sensor array comprised of chemoresponsive dyes coupled to a commercially available 8-bit flatbed scanner. Principle component analysis of the composite magnitude and kinetics of color change for the array of dye spots over the entire dynamic range resulted in 100% classification. This was achieved by including chemoresponsive dyes which reacted specifically with H 2 S at different detection thresholds.

The ability of chemical sensor array (CSA) technology to identify multiple gaseous analytes and differentiate between various analyte concentrations has been documented. To date, CSA response was monitored using a flatbed scanner driven by a personal computer. While this system is suitable for use in a laboratory setting it is not suitable for use in the field for environmental monitoring. We describe herein progress made towards the development of a rapid, inexpensive, portable, battery-operated, handheld device based on CSA technology for the detection of toxic industrial compounds (TICs). This prototype successfully differentiates between four TICs at both permissible exposure limit (PEL) and immediately dangerous to life and health (IDLH) concentrations, and three interferent gases, in less than 2 min.

The development of an array of chemically-responsive dyes on a porous membrane and in its use as a general sensor for odors and volatile organic compounds (VOCs) is reviewed. These colorimetric sensor arrays (CSA) act as an "optoelectronic nose" by using an array of multiple dyes whose color changes are based on the full range of intermolecular interactions. The CSA is digitally imaged before and after exposure and the resulting difference map provides a digital fingerprint for any VOC or mixture of odorants. The result is an enormous increase in discriminatory power among odorants compared to prior electronic nose technologies. For the detection of biologically important analytes, including amines, carboxylic acids, and thiols, high sensitivities (ppbv) have been demonstrated. The array is essentially non-responsive to changes in humidity due to the hydrophobicity of the dyes and membrane.

We present here a comprehensive account of the formulation and pilot applications of the second-order perturbative analogue of the recently proposed unitary group adapted state-specific multireference coupled cluster theory (UGA-SSMRCC), which we call as the UGA-SSMRPT2. We also discuss the essential similarities and differences between the UGA-SSMRPT2 and the allied SA-SSMRPT2. Our theory, like its parent UGA-SSMRCC formalism, is size-extensive. However, because of the noninvariance of the theory with respect to the transformation among the active orbitals, it requires the use of localized orbitals to ensure size-consistency. We have demonstrated the performance of the formalism with a set of pilot applications, exploring (a) the accuracy of the potential energy surface (PES) of a set of small prototypical difficult molecules in their various low-lying states, using natural, pseudocanonical and localized orbitals and compared the respective nonparallelity errors (NPE) and the mean average deviations (MAD) vis-a-vis the full CI results with the same basis; (b) the efficacy of localized active orbitals to ensure and demonstrate manifest size-consistency with respect to fragmentation. We found that natural orbitals lead to the best overall PES, as evidenced by the NPE and MAD values. The MRMP2 results for individual states and of the MCQDPT2 for multiple states displaying avoided curve crossings are uniformly poorer as compared with the UGA-SSMRPT2 results. The striking aspect of the size-consistency check is the complete insensitivity of the sum of fragment energies with given fragment spin-multiplicities, which are obtained as the asymptotic limit of super-molecules with different coupled spins.

The development of colorimetric sensor arrays for the detection of volatile organic compounds is reported. Using an array of chemo-responsive dyes, enormous discriminatory power is created in a simple device that can imaged easily with an ordinary flat-bed scanner. High sensitivities (ppb) have been demonstrated for the detection of biologically important analytes, including amines, carboxylic acids, and thiols. By the proper choice of dyes and substrate, the array can be made essentially non-responsive to changes in humidity.

Based on the spectroscopic constants derived from highly accurate potential-energy surfaces, the SeD radical is identified as a spectroscopic probe for measuring spatial and temporal variation of fundamental physical constants such as the fine-structure constant (denoted as $\ensuremath{\alpha}=\frac{{e}^{2}}{\ensuremath{\hbar}c}$) and the proton-to-electron mass ratio (denoted as $\ensuremath{\mu}=\frac{{m}_{p}}{{m}_{e}}$). The ground state of SeD $({X}^{2}\ensuremath{\Pi})$, due to spin-orbit coupling, splits into two fine-structure multiplets ${}^{2}{\ensuremath{\Pi}}_{\frac{3}{2}}$ and ${}^{2}{\ensuremath{\Pi}}_{\frac{1}{2}}$. The potential-energy surfaces of these spin-orbit components are derived from a state of the art electronic structure method, MRCI + Q inclusive of scalar relativistic effects with the spin-orbit effects accounted for through the Breit-Pauli operator. The relevant spectroscopic data are evaluated using a Murrel-Sorbie fit to the potential-energy surfaces. The spin-orbit splitting ${\ensuremath{\omega}}_{f}$ between the two multiplets is similar in magnitude with the harmonic frequency ${\ensuremath{\omega}}_{e}$ of the diatomic molecule. The amplification factor $K$ derived from this theoretical method for this particular molecule can be as large as 350; on the lower side it can be about 34. The significantly large values of $K$ indicate that the SeD radical can be a plausible experimental candidate for measuring variation in $\ensuremath{\alpha}$ and $\ensuremath{\mu}$.

A few fixed distance covalently linked porphyrin–quinone molecules have been synthesized in which a benzoquinone is directly attached to a meso /β-pyrrole position of tri(phenyl/pentafluorophenyl)/tetraphenylporphyrins. The choice of fluoroarylporphyrins permit modulation of Δ G ET values for photoinduced electron-transfer reactions in these systems. All short distance porphyrin–quinone molecules showed efficient quenching of the porphyrin singlet excited state. The electrochemical redox data coupled with the steady-state and time-resolved singlet emission data are analysed to evaluate the dependence of Δ G ET values on the rate of electron transfer ( k ET ) in these systems. The meso -trifluoroarylporphyrin–quinones are found to be sensitive probes of the surrounding dielectric environment. Varying solvent polarity on the mechanism of fluorescence quenching and k ET values revealed that short donor–acceptor distance and the solvent dielectric relaxation properties play a dominant role.

Dimers constituting differing porphyrin basicities undergo selective demetallation or protonation of one unit of the dimer. The efficiency of singlet excited energy transfer from neutral free-base/zinc(II) porphyrin to diprotonated porphyrin unit could be fine tuned by varying acidity in the covalently linked dimers.

Two novel porphyrin trimers bearing different metal centres and/or different peripheral substituents have been synthesized. These systems display interesting spectral and electrochemical redox properties.

Spectroscopic and electrochemical redox properties of a series of fluorinated porphyrins bearing donor-acceptor groups and their Zn(II) and Cu(II) derivatives are presented. The magnitude of the ring reduction potentials and charge transfer properties derived from spectral data depend on the nature and position of the substituent(s), ( nitro dimethylamino ) and the central metal ions.

Nematic liquid crystals (NLCs) have traditionally been used in displays and other electro-optical applications where the orientation of NLC is manipulated by using an external electric field to display the information. In recent years, there have been significant advances in unconventional applications of NLCs in photonics, sensors, and diagnostics. In this paper, the application of NLCs for detection of vapor phase chemicals and biological entities is presented. When NLCs are in contact with another medium (solid, liquid or air) the delicate interplay between the properties of medium and NLCs determines the nature of the alignment assumed by NLCs at the interface. Interfaces functionalized with select chemical or biological entities promote alignment of NLCs in predetermined orientations (perpendicular or parallel to that interface) that are primarily dictated by local interactions at the interface. When these interfaces are exposed to target analytes, the interactions at the interfaces are perturbed and the NLC films undergo orientational transitions from perpendicular to parallel alignment, or vice versa. The orientational transition can be detected by viewing the film of NLCs between crossed polarizers (optical signal) or by measuring the differential capacitance associated with the change in alignment of NLCs (electrical signal). By engineering surfaces with different interfacial properties, sensors based on this principle have been demonstrated to selectively detect a wide variety of chemical and biological analytes that have relevance in industrial hygiene, environmental monitoring, homeland security, diagnostics, and biomedical applications.

Two novel porphyrin trimers bearing different metal centres and/or different peripheral substituents have been synthesized. These systems display interesting spectral and electrochemical redox properties.

Rhus semialata Murr. (Anacardiaceae) is a deciduous tree of north eastern India. The fruit of this plant is traditionally used to control diarrhoea and dysentery. The Present study was undertaken to evaluate anti-diarrhoeal potency of methanol extract of fruits of R. semialata using Wister albino rats to substantiate folklore claims. The extract at graded doses (100, 200, 400 and 600 mg/kg body weight) was investigated for anti-diarrhoeal activity in term of reduction in the rate of defecation in castor oil induced diarrhoea. To understand the mechanism of its anti-diarrhoeal activity, the gastrointestinal transit and PGE2-induced intestinal fluid accumulation (enteropooling) were further evaluated. At graded doses, the extract showed a remarkable anti-diarrhoeal activity evidenced by the reduction in the rate of defecation up to 80.70 % of control diarrhoeal animals at the dose of 600 mg/kg body weight. Results are comparable to that of standard drug diphenoxylate (50 mg/kg body weight). Extract produced profound decrease in intestinal transit (8.02 – 47.05 %) at selected doses comparable to that of single intraperitoneal injection of standard drug atropine sulphate at doses of 0.1 mg/kg body weight. It significantly inhibited PGE2 -induced enteropooling (21.98 – 56.03 %). The results indicated that the methanol extract of the fruits of R. semialata possesses significant anti-diarrhoeal effect and substantiated the use of this herbal remedy as a non-specific treatment for diarrhoea in folk medicine.

Multicast is a key service for many audio and video applications, yet it continues to be a challenging Internet service to deploy. While much attention has been given to a number of problems associated with multicast, two closely related problems in particular have received almost no attention. First, there is essentially no host support for dealing with the variety of ways to join a multicast group, and second, there is a complete absence of group join success or failure feedback from the network. The lack of a straightforward way to robustly join a multicast group and then to know whether the join has been successful is possibly the biggest limitation for multicast application developers today. In this study we develop a robust solution to determine the existence and nature of multicast service in the network. We consider two options: (1) the use of existing protocol features to extract the required information, and (2) the introduction of new protocol extensions to directly query the network. Our results indicate that while a truly robust group join is possible only when there is network support, these additional changes are difficult to deploy. Our evaluation implements a proof-of-concept prototype to determine the existence and nature of the multicast service in the network.

CuII- and ZnII-based donor−acceptor porphyrins have been examined for second-order nonlinear optics using the hyper-Rayleigh scattering technique at 1064 nm. Introduction of the metal ions enhances...

Over the past few decades there has been remarkable progress in the synthesis of molecular scaffolds based on superstructured porphyrins.1 A number of these modified porphyrins have been synthesized to mimic various aspects of the enzymatic functions of heme proteins, especially oxygen binding (myoglobin and hemoglobin), and substrate oxidation (cytochrome P-450).1,2 The notable property of many heme proteins is their remarkable substrate selectivity; the development of highly regioselective synthetic catalysts, however, is still at an early stage. Discrimination of one site on a molecule from another and distinguishing among many similar molecules presents a difficult and important challenge to both industrial and biological chemistry.3 Although the axial ligation properties of simple synthetic metalloporphyrins are well documented in literature,4 size and shape control of ligation to peripherally modified metalloporphyrins has been largely unexplored, with few notable exceptions, where only limited selectivities have been observed.5 We report here the synthesis, characterization, and remarkable shape-selective ligation of silyl ether-metalloporphyrin scaffolds derived from the reaction of 5,10,15,20-tetrakis(2′,6′-dihydroxyphenyl)porphyrinatozinc(II) with tert-butyldimethylsilyl chloride, whereby the two faces of the Zn(II) porphyrin were protected with six, seven, or eight siloxyl groups. This results in a set of three porphyrins of nearly similar electronics but with different steric encumbrance around the central metal atom present in the porphyrin. Ligation to Zn by classes of different sized ligands reveals shape selectivities as large as 107. A family of siloxyl-substituted bis-pocket porphyrins were prepared according to the process in Scheme 1.6 Zn[(OH)6PP] and Zn[(OH)8PP] were obtained5a from demethylation7 of corresponding free base methoxy compounds followed by zinc(II) insertion. The methoxy porphyrins were synthesized by acid catalyzed condensation of pyrrole with respective benzaldehydes following Lindsey procedures.8 Metalation was done in methanol with Zn(O2CCH3)2. The tert-butyldimethylsilyl groups were incorporated into the metalloporphyrin by stirring a DMF solution of hydroxyporphyrin complex with TBDMSiCl in the presence of imidazole.9 The octa (Zn(Si8PP)), hepta (Zn(Si7OHPP)), and hexa (Zn(Si6PP)) silyl ether porphyrins were obtained from Zn[(OH)8PP] and Zn[(OH)6PP], respectively. The compounds were purified by silica gel column chromatography and fully characterized by UV-visible, 1H NMR, HPLC, and MALDI-TOF MS. The size and shape selectivities of the binding sites of these bis-pocket Zn silyl ether porphyrins were probed using the axial ligation of various nitrogenous bases of different shapes and sizes in toluene at 25 °C. Zn(II) porphyrins were chosen for this study because, in solution, they generally bind only a single axial ligand. Successive addition of ligand to the porphyrin solutions caused a red-shift of the Soret band typical of coordination to zinc porphyrin complexes. There is no evidence from the electronic spectra of these porphyrins for significant distortions of the electronic structure of the porphyrin. The binding constants (Keq) and binding composition (always 1:1) were evaluated using standard procedures.10 The Keq values of the silyl ether porphyrins with nitrogenous bases of different classes are compared with the sterically undemanding Zn(TPP) in Figure 1. It is worth noting the parallel between shape selectivity in these equilibrium measurements and prior kinetically controlled epoxidation and hydroxylation.2,11 While direct comparisons are not yet available, the selectivity for equilibrated ligation appears to be substantially larger than that for irreversible oxidations of similarly shaped substrates. The binding constants of silyl ether porphyrins are remarkably sensitive to the shape and size of the substrates relative to Zn(TPP) (Figure 1). The binding constants of different amines could be controlled over a range of 101 to 107 relative to Zn(TPP). We believe that these selectivities originate from strong steric repulsions created by the methyl groups of the tert-butyldimethylsiloxyl substituents. The steric congestion caused by these bulky silyl ether groups is pronounced eVen for linear amines and small cyclic amines (e.g., azetidine and pyrrolidine). There are very large differences in Keq for porphyrins having three versus four silyl ether groups on each face (e.g., hexavs

Synthesis and characterisation of β-pyrrole substituted porphyrin-quinone system is presented. Optical and electrochemical studies showed the energy of charge transfer (CT) state is dependent on the position of quinone substituent (β-pyrrole or meso carbon) in the porphyrin ring.