Synthesis and Characterization of Novel Ag(I)-15C5 Complexes
Seema Chitlangia1, Rajeev Ranjan2*
1Univ. Department of Chemistry, Ranchi University, Ranchi
2Univ. Department of Chemistry, DSPM University, Ranchi
*Corresponding Author E-mail: rajeevran7@yahoo.com
ABSTRACT:
Crown ether is a generic name given to macrocyclic polyethers containing ethylene bridges separating electronegative oxygen atoms.1,2 They typically contain central electron rich hydrophilic cavity with diameter varying from 1.2-6.0 Å. The hydrophilic cavity is ringed with electronegative binding hetero atoms such as oxygen, nitrogen, sulphur etc., which in turn are surrounded by a collar of –CH2– groups forming a frame work –[CH2CH2X]–, where X is a hetero atom. Such frame work is flexible and exhibits hydrophobic behavior. The hydrophobic exteriors allow them to solubilize ionic substances into non-aqueous solutions and in membrane media. Such properties facilitate for their use as extractants and membrane carriers. When the inorganic cation fits into the cavity of crown ether or sandwiched between two crown ether molecules it becomes a lipophilic species. The discovery of crown ethers led to enormous advances in chemistry.
Crown ethers and related polyether ligands have been employed as ligands for a variety of substrates. These macrocycles can be used to accommodate specific metal ions by the fine tuning of the ligand design features3-5, such as the macrocyclic hole size6, number and sizes of the chelate rings, and nature of the ligand backbone7-10. The binding ability of such molecules to bind metal ions have been comprehensively reviewed.11,12 The properties of polyether donors have since been used to prepare complexes of small molecules13 and even to generate supramolecular assemblies14. Crown ethers have been used extensively in the field of organic synthesis, for membrane transport studies, phase transfer catalysis, ion selective electrodes, molecular recognition, chromoionophores, fluoroionophores and for extractive separation analysis using chromatography and solvent extraction techniques.15-17 Many applications associated with the binding and ligand chemistry of polyethers have been developed ranging from ion sensing,18-20 separation techniques,21 supramolecular chemistry,22 molecular machines, synthetic ion channels,23 biomedical applications,24-26 permanently porous liquids,27and much more.
No systematic efforts were made for the application of crown ethers in separation studies of various elements in multicomponent mixtures. Many theoretical studies have been focused on the structure and selectivity of crown ethers towards metal ions.28-31 Coordination chemistry of macrocyclic ligands with silver ion has been a fascinating area of current research interest to the modern chemists all over the world.32-33 Interest and quest in designing new macrocyclic ligands is due to their potential use in biological systems: as synthetic ionophores, as therapeutic reagents for the treatment of metal intoxication, as cyclic antibiotics, to study the biological guest-host interactions, in solvent extraction and in catalysis.34-40
MATERIALS AND METHODS:
The nitrophenols and crown ethers used were of E. Merck and S. Aldrich respectively. The commercially available regents of AR grade were used without further purification. Results of elemental analysis of synthesized compounds agreed with required value within experimental error. IR spectra were recorded by Perkin Elmer RX1 (4000-450 cm-1) at SAIF-CDRI. UV-visible spectral data were recorded through Systronic double beam spectrophotometer-2203 (600-200 nm). The 1H−NMR spectra of ligands and synthesized complexes were recorded in CDCl3 by Bruker DRX-300 at SAIF-CDRI.
EXPERIMENTAL:
Preparation of silver salt of nitrophenols; Ag (ONP), Ag (DNP) and Ag (TNP) :
About 4 mmol(0.644 gm) of sodium salt of 2-nitrophenol was taken in a conical flask and 25 ml of 95% (V/V) ethanol was added to it. The ethanolic solution of sodium salt of 2-nitrophenol was heated on a water bath and continuously shaken till gets completely dissolved and the solution becomes homogeneous. Then, 4 mmol of AgNO3 (0.68 gm) was dissolved in 25 ml of 95% (V/V) ethanol and continuously shaken till the silver nitrate gets completely dissolved. The freshly prepared ethanolic solution of silver nitrate was slowly added to the ethanolic solution of sodium salt of 2-nitrophenol and continuously shaken. On adding the ethanolic solution of silver nitrate, brownish orange coloured silver salt of 2-nitrophenol (AgONP) precipitated out.17 The mixture was continuously stirred on hot plate equipped with magnetic stirrer for 45 minutes to ensure complete precipitation.
Similarly, silver salt of 2,4-dinitrophenol (AgDNP), and 2,4,6-trinitrophenol (AgTNP) were prepared by taking 4 mmol of appropriate sodium salt and using the above described procedure. Some physical properties of synthesized silver salts are given in table-1.
Table-1 Physical properties of silver salts
|
Compound |
Colour |
Melting point (0C) |
% Nitrogen |
|
AgONP |
Brownish orange |
270d |
5.69 |
|
AgDNP |
Yellow |
265d |
9.62 |
|
AgTNP |
Yellowish Brown |
245e |
12.51 |
d – decomposition temp, e – explosion temp
Preparation of adducts of 15-crown-5 ether with silver salts of 2-nitrophenol, 2,4-dinitrophenol and 2,4,6-trinitrophenol:
The dried organic salt (0.002 mol) was suspended in 50 ml dry methanol and heated it with constant stirring to get a clear solution. Stoichiometric proportion of 15-crown-5 ether (0.002 mol) was added in that and then the reaction mixture was refluxed in an inert medium on a hot plate equipped with magnetic stirrer at 50-550C. A clear solution was formed. It was filtered and concentrated to half of its bulk. On cooling this solution, solid crystalline product began to precipitate. The product was separated out and allowed to stand overnight then filtered on a buchner funnel. The compound was washed with few drops of dry methanol and dried over KOH desiccator.
15C5.Ag(ONP): C16H24NO8Ag
15C5.Ag(DNP): C16H23N2O10Ag
15C5.Ag(TNP): C16H22N3O12Ag
Table-2 Percentage composition of silver-crown ether complexes
|
Compound |
% C |
% N |
% O |
% Ag |
|
15C5.Ag(ONP) |
42.36 |
2.74 |
28.22 |
21.13 |
|
15C5.Ag(DNP) |
38.93 |
5.04 |
31.69 |
19.42 |
|
15C5.Ag(TNP) |
36.01 |
7.00 |
34.65 |
17.96 |
Table-3 Prominent FTIR bands of silver-crown ether complexes (in cm-1)
|
Compound |
νs(C-O-C) |
ν1(-NO2 ), ν3 (-NO2) |
νs(C-H) bending νas(-CH2-)bending |
|
AgONP15 |
1102.76 |
1632.53, 833.28 |
1454.68, 1355.74 |
|
AgDNP15 |
1093.54 |
1645.09, 879.94 |
1454.01, 1357.12 |
|
AgTNP15 |
1099.12 |
1633.89, 870.01 |
1452.05, 1303.52 |
Table-4 Prominent FTIR bands of silver-crown ether complexes (in cm-1)
|
Compound |
ν(M-O) / ν(M-Ocrown) |
ν (N=O)str in C-NO2 |
|
AgONP15 |
480 |
1250 |
|
AgDNP15 |
510, 525 |
1257.16 |
|
AgTNP15 |
470, 598 |
1280 |
RESULT AND DISCUSSION:
UV-Visible study
Saturated crown ethers do not show any absorption above 220 nm. Electronic absorption spectra of synthesized compounds provide small but significant evidence of bonding in complexes. The electronic spectral studies of synthesized complexes shows only some deviation of p - p*, n - p*, s - p* and s - s* transitions due to shifting of electron density from donor atoms to cationic species. There is also good probability of d–d transitions in complexes, which is characteristic of transition and rare earth metal complexes. The slight change in spectral band position is usually taken as either solvent effect or interaction of electron cloud of donor atom of ligand with silver ion. The bond energy in organic compound possess energy equivalent to absorption energy of ultraviolet or visible radiation as they form bonds by ion-dipole interactions and/or involvement of non-bonding electrons with central metal ions.41-43 The electrons of bonding orbitals can go to higher energy by excitement due to absorption of radiation in UV region. In all nitrophenols, important electronic transitions are n - s*, p - p* transition of nitro group (–NO2) and p - p* transition of phenyl group. The n - s* transition of phenolic (C–O) group is observed at high energy and phenyl ring p - p*, s - s* transitions between 180–250 nm region. The antibonding orbitals s* and p* are quantized energy level of higher energies. Besides bonding electronic transitions, intermolecular transition known as charge transfers (C–T) and M « L transitions of high intensity are usually observed in dyes, complex molecule and coordination complexes.44
FTIR study:
The infrared spectra of aromatic as well as aliphatic crown ether shows the presence of ether linkages by a strong broad band around 1230 cm-1 for aromatic-O-aliphatic and a band at 1100 cm-1 for aliphatic-O-aliphatic group. The 15C5 crown ethers in uncoordinated state display n(C–O–C) stretching vibration band near 1100±22 cm-1. This n(C–O–C) vibration band shifted to lower frequency by 10-15 cm-1 in almost all complexes suggesting crown ether’s oxygen interaction with silver ion.45 The n(O-H) stretching vibration in almost all nitrophenols are observed as very broad and medium band in the region 3150–3320 cm-1 which almost disappears in their salts. The disappearance of n(O-H) band suggests bonding of phenolic oxygen with metal ions on deprotonation of phenolic -OH group. The n(C–O) band shifts to higher frequency due to acquiring higher (C–O) bond order on deprotonation in silver metal salts. This increase is attributed to bonding of phenolic oxygens (C–O) in all complexes. The stretching bands of -NO2 in AgONP, AgDNP and AgTNP are at around 1605 cm-1, 1618±5 cm-1 and 1642±5cm-1. These bands shifted to lower frequency in complexes. The n(NO2) located near 845±10 cm-1 also shifted to the lower vibrational frequency in the complexes. The FTIR band observed near 740–780 cm-1 is attributed to phenyl ring n(C–H) out of plane bending vibration. The 15-crown-5 ether display n(–CH2–) stretching vibrations at 2920±10 cm-1 and these are little affected on bonding with silver ion in complexes. Some hygroscopic complexes in their FTIR spectrum displays a broad band around 3352–3420 cm-1, with maxima near 3405±10 cm-1.46,47 In the far-IR region new bands, absent in the spectrum of the free ligands, are found in the 470–590 cm-1 region, which may be assigned to the n(Ag–Ocrown) stretching frequency.48-50 Some FTIR-spectrum of the synthesized complexes are shown in figure 1.1–1.3. Since nature of FTIR peaks are almost similar thus, spectrum of only three complexes, [Ag+.15C5](ONP–), [Ag+.15C5](DNP–) and [Ag+.15C5](TNP–) are shown. Thus FTIR studies of the complexes also suggest bonding of silver salt of nitrophenols with crown ether oxygen atoms.
Fig. 1.1. FTIR Spectrum of [Ag+.15C5](ONP–)
Fig. 1.2. FTIR Spectrum of [Ag+.15C5](DNP–)
Fig. 1.3. FTIR Spectrum of [Ag+.15C5](TNP–)
1H-NMR Study:
The NMR technique is a powerful tool for studying the complexation of crown ethers and metal cations. Various NMR parameters, such as the 1H chemical shifts, 13C chemical shifts, vicinal H-H coupling constants, have been used to estimate the dihedral angle within the -O-CH2-CH2-O- fragments and degree of in-plane interactions. The 1H-NMR spectrum of uncoordinated crown ethers and adduct complexes of silver ion provide useful information regarding structure of complexes. Qualitative and quantitative information on some crown ether interactions leading to supramolecule formation is available from detailed measurements of the chemical shift variations and from the relaxation rates of protons of the crown ethers as a function of the concentration of the silver-metal ion with the crown ether.51 The conformation and the binding of small-ring dibenzo crown ethers with small cations in solution have been previously investigated using NMR techniques, supplemented by quantum chemical calculations.52 The 1H-NMR study of synthesized crown ether complexes provides useful information regarding structure of complexes.53 The chemical shift of proton in 15C5 (figure 2) shows solvent dependent chemical shift and feels noticeable shifts change upon complexation. After formation of the complex [Ag.L](Pic-), the ethereal proton chemical shift d(–CH2–O–) sows downfield shift [∆d(–CH2–O–)] by 0.08-0.25 ppm, showing metal-crown ether bond formation.54-56 The relative change in the downfield shift shows the relative strength of the synthesized complexes.57-58 In all cases, the exchange between free and complexed crown was fast on the 1H-NMR time scale and only a single population average 1H-signal was observed. The 1H-NMR spectrum of 15C5 shows peaks at, d(1H)=3.920–3.926 (20H, 5 –CH2CH2O–), in CDCl3.56 The shift of –CH2– signals in complexes from free crown ether suggested the coordination of crown ether oxygen of 15C559 with silver ion.60-62 Some 1H-NMR spectrum of the synthesized complexes along with 15C5 are shown in figure 3.1–3.2 Since the nature of 1H-NMR peaks are almost similar thus, spectrum of only one compound is shown. Figure-4 shows proposed structures of complexes [M+.L](Pic–), where M = Ag+, L = 15C5 and OX = ONP–/ DNP–/TNP– based on all reported evidences.
Fig. 2. 15-Crown-5
Fig. 3.1. 1H-NMR Spectrum of 15C5
Fig. 3.2. 1H-NMR Spectrum of [Ag+.15C5](TNP–)
Fig. 4. Proposed structures of complexes [M+. L] (Pic–), where M = Ag+, L = 15C5 and OX = ONP–/ DNP–/TNP–
ACKNOWLEDGEMENT:
We are thankful to the Head, SAIF, CDRI, Lukhnow, for providing FTIR-spectra, 1H-NMR spectra and necessary facilities.
REFERENCES:
1. Charles J Pedersen. Cyclic polyethers and their complexes with metal salts. Journal of the American Chemical Society. 89 (26), 1967, 7017-7036.
2. Charles J Pedersen. Macrocyclic polyether sulfides. Journal of the American Chemical Society. 36 (2), 1971, 254-257.
3. Ryoji Kusaka, Yoshiya Inokuchi, Takeharu Haino, and Takayuki Ebata. Structures of (3n-crown-n)–phenol (n = 4, 5, 6, 8) host–guest complexes: Formation of a uniquely stable complex for n = 6 via collective intermolecular interaction. The Journal of Physical Chemistry Letters. 3 (10), 2012, 1414-1420.
4. Qing He, Gabriela I Vargas-Zúñiga, Seung Hyun Kim, Sung Kuk Kim, Jonathan L Sessler. Macrocycles as ion pair receptors. Chemical Reviews 2019. 119 (17), 9753-9835.
5. Vincent Guillerm and Daniel Maspoch. Geometry mismatch and reticular chemistry: Strategies to assemble metal–organic frameworks with non-default topologies. Journal of the American Chemical Society. 14 (42), 2019, 16517-16538.
6. Ayan Datta. Role of metal ions (M = Li+, Na+, and K+) and pore sizes (Crown-4, Crown-5, and Crown-6) on linear and nonlinear optical properties: New materials for optical birefringence. The Journal of Physical Chemistry C. 113 (8), 2009, 3339-3344.
7. Dario Braga, Massimo Gandolfi, Matteo Lusi, Marco Polito, Katia Rubini and Fabrizia Grepioni. Solution and solid-state preparation of 18-crown-6 and 15-crown-5 adducts of hydrogen sulfate salts and an investigation of the reversible dehydration processes. Crystal Growth & Design. 7 (5), 2007, 919-924.
8. Joseph D. Anderson, Eric S. Paulsen, David V. Dearden. Alkali metal binding energies of dibenzo-18-crown-6: Experimental and computational results. International Journal of Mass Spectrometry. 227(1), 2003, 63-76.
9. Brandi L. Schottel, Helen T. Chifotides, Mikhail Shatruk, Abdellatif Chouai, Lisa M. Pérez, John Bacsa and Kim R. Dunbar. Anion−π interactions as controlling elements in self-assembly reactions of Ag(I) complexes with π-acidic aromatic rings. Journal of the American Chemical Society. 128 (17), 2006, 5895-5912.
10. Alireza Azhdari Tehrani, Sedigheh Abedi and Ali Morsali . Effects of orthohalogen substituents on nitrate binding in urea-based silver(I) coordination polymers. Crystal Growth & Design. 17 (1), 2017, 255-261.
11. T. P. Hanusa, in Coordination Chemistry of the s, p, and f Metals, Elsevier, Amsterdam, 2003, vol. 3, pp. 1-92.
12. J. L. Dye, M. Y. Redko, R. H. Huang and J. E. Jackson, in Advances in Inorganic Chemistry: Including Bioinorganic Studies, Vol 59: Template Effects and Molecular Organization, eds. R. VanEldik and K. BowmanJames, 2007, vol. 59, pp. 205-231.
13. Peter C. Junk, Crown ethers as stabilising ligands for oxonium ions, New Journal of Chemistry, 32(5), 2008, 762-773.
14. A. Harada, A. Hashidzume, H. Yamaguchi and Y. Takashima, Polymeric rotaxanes, Chemical Reviews, 109(11), 2009, 5974-6023.
15. Rajeev Ranjan and Ramjatan Sinha. Synthesis of some benzocrown ether derivatives and their solvent extraction with organic salts of alkali metals. Asian Journal of Research in Chemistry. 5 (11), 2012, 1335-1337.
16. Rajeev Ranjan. Study of complexation behavior of some benzocrown ether derivatives by solvent extraction with organic salts of alkaline earth metal ions. Asian Journal of Research in Chemistry. 5 (12), 2012, 1480-1482.
17. Rajeev Ranjan. Study of complexation behavior of Ag(I) ion with some benzocrown ether derivatives by solvent extraction method. Asian Journal of Research in Chemistry. 6 (9), 2013, 819-821.
18. R. A. Potyrailo, Polymeric sensor materials: towards an alliance of combinatorial and rotational design tools?, Angewandte Chemie International Edition, 45(2), 2006, 702-723.
19. G. Aragay, J. Pons and A. Merkoci, Recent trends in macro-, micro-, and nanomaterial-based tools and strategies for heavy-metal detection, Chemical Reviews, 111(5), 2011, 3433-3458.
20. Francis A. Christy and Pranav S. Shrivastav, Conductometric studies on cation-crown ether complexes:a review, Critical Reviews in Analytical Chemistry, 41(3), 2011, 236-269.
21. Roya M. Kakhki, Application of crown ethers as stationary phase in chromatographic methods, Journal of Inclusion Phenomena and Macrocyclic Chemistry, 75(1-2), 2013, 11-22.
22. Timothy R. Cook, Yao-Rong Zheng and Peter J. Stang, Metal-organic frameworks and self-assembled supramolecular coordination complexes: comparing and contrasting the design, synthesis, andfunctionality of metal-organic materials, Chemical Reviews, 113(1), 2013, 734-777.
23. George W. Gokel and I. Alexandru Carasel, Biologically active synthetic ion transporters, Chemical Society Reviews, 36(2), 2007, 378-389.
24. Dana A. Uhlenheuer, Katja Petkau and Luc Brunsveld, Combining supramolecular chemistry with biology, Chemical Society Reviews, 39(8), 2010, 2817-2826.
25. Marijeta Kralj, Ljerka Tusek-Bozic and Leo Frkanec, Biomedical potential of crown ethers: prospective antitumor agents, ChemMedChem:Chemistry Enabling Drug Discovery, 3(10), 2008, 1478-1492.
26. Abdalla A. Elbashir and Hassan Y. Aboul-Enein, Application of crown ethers as buffer additives in capillary electrophoresis, Current Pharmaceutical Analysis, 6, 2010, 101-113.
27. Nicola Giri, Mario G. Del Popolo, Gavin Melaugh, Rebecca L. Greenaway, Klaus Ratzke, Tonjes Koschine, Laura Pison, Margarida F. Costa Gomes, Andrew I. Cooper and Stuart L. James, Liquids with permanent porosity, Nature, 527(7577), 2015, 216-220.
28. Glendening ED, Feller D, Thompson MA. An ab initio investigation of the structure and alkali metal cation selectivity of 18-crown-6, Journal of the American Chemical Society. 116 (23), 1994, 10657-10669.
29. Hag-Sung Kim. Monte Carlo simulation study of solvent effect on Δlog Ks of Rb+ and K+ ion to 18-crown-6. The Journal of Physical Chemistry B. 106 (44), 2002, 11579-11584.
30. Hag-Sung Kim. Selectivity of 18-Crown-6 between Cs+ and Rb+ ion: Solvent effect by a Monte Carlo simulation study. The Journal of Physical Chemistry B, 108 (31), 2004, 11753-11759.
31. Thompson MA, Glendening ED, Feller D. The nature of K+/crown ether interactions: A hybrid quantum mechanical –molecular mechanical study. J. Phys. Chem. 98, 1994, 10465-10476.
32. Toshio Shimizu, Mari Kawaguchi, Takahiro Tsuchiya, Kazunori Hirabayashi, and Nobumasa Kamigata. Unsaturated selenacrown ethers: Synthesis, structure, and formation of silver complexes. The Journal of Organic Chemistry. 70 (13), 2005, 5036-5044.
33. Ning Cao, Yan Wang, Xujun Zheng, Tianyu Jiao and Hao Li. Controllable self-assembly of pills and cages via imine condensation for silver cation detection. Organic Letters. 20 (23), 2018, 7447-7450.
34. Minjae Lee, Daniel V Schoonover, Anthony P Gies, David M Hercules and Harry W Gibson . Synthesis of complementary host- and guest-functionalized polymeric building blocks and their self-assembling behavior. Macromolecules. 42 (17), 2009, 6483-6494.
35. Nathalia F Carvalho and Josefredo R Pliego Jr. . Theoretical design and calculation of a crown ether phase transfer catalyst scaffold for nucleophilic fluorination merging two catalytic concepts. The Journal of Organic Chemistry. 81 (18), 2016, 8455-8463.
36. Ying Liu, Jie Shen, Chang Sun, Changliang Ren, and Huaqiang Zeng . Intramolecularly hydrogen-bonded aromatic pentamers as modularly tunable macrocyclic receptors for selective recognition of metal ions. Journal of the American Chemical Society. 137 (37), 2015, 12055-12063.
37. Yukihiro Yoshida, Mitsuhiko Maesato, Yuto Nakamura, Manabu Ishikawa, Hideki Yamochi, Gunzi Saito, Hideo Kishida, Hiroshi Kitagawa. Bis(ethylenedithio)tetrathiafulvalene cation radical salts composed of nonuniform silver(I) complex polyanions. Inorganic Chemistry. 58 (24), 2019 16703-16711.
38. Yan Sun, Chongyi Chen, Peter J. Stang. Soft materials with diverse suprastructures via the self-assembly of metal–organic complexes. Accounts of Chemical Research. 52 (3), 2019, 802-817.
39. Abir Goswami, Suchismita Saha, Pronay Kumar Biswas, Michael Schmittel. (Nano)mechanical motion triggered by metal coordination: From functional devices to networked multicomponent catalytic machinery. Chemical Reviews. 120 (1), 2020, 125-199.
40. Paolo Della Sala, Rocco Del Regno, Carmen Talotta, Amedeo Capobianco, Neal Hickey, Silvano Geremia, Margherita De Rosa, Aldo Spinella, Annunziata Soriente, Placido Neri, Carmine Gaeta. Prismarenes: A new class of macrocyclic hosts obtained by templation in a thermodynamically controlled synthesis. Journal of the American Chemical Society. 142 (4), 2020, 1752-1756.
41. Yoshiya Inokuchi, Maki Nakatsuma, Motoki Kida, and Takayuki Ebata. Conformation of Alkali Metal Ion-Benzo-12-Crown-4 Complexes Investigated by UV Photodissociation and UV–UV Hole-Burning Spectroscopy. The Journal of Physical Chemistry A. 120 (32), 2016, 6394-6401.
42. Yoshiya Inokuchi, Oleg V. Boyarkin, Ryoji Kusaka, Takeharu Haino, Takayuki Ebata, and Thomas R. Rizzo . Ion Selectivity of Crown Ethers Investigated by UV and IR Spectroscopy in a Cold Ion Trap. The Journal of Physical Chemistry A, 116 (16), 2012, 4057-4068.
43. Yoshiya Inokuchi, Takayuki Ebata, Thomas R. Rizzo. Microhydration of Dibenzo-18-Crown-6 Complexes with K+, Rb+, and Cs+ Investigated by Cold UV and IR Spectroscopy in the Gas Phase. The Journal of Physical Chemistry A. 122 (15), 2018, 3754-3763.
44. Yoshiya Inokuchi, Takayuki Ebata, Thomas R. Rizzo. UV and IR Spectroscopy of Transition Metal–Crown Ether Complexes in the Gas Phase: Mn2+(benzo-15-crown-5)(H2O)0–2. The Journal of Physical Chemistry A. 123 (31), 2019, 6781-6786.
45. Robert A Condrate, Kazuo Nakamoto. Infrared spectra and normal coordinate analysis of metal glycino complexes. The Journal of Chemical Physics. 42(7), 1965, 2590-2598.
46. Jason D Rodriguez, Timothy D Vaden and James M Lisy. Infrared Spectroscopy of Ionophore-Model Systems: Hydrated Alkali Metal Ion 18-Crown-6 Ether Complexes. Journal of the American Chemical Society. 131 (47), 2009, 17277-17285.
47. Cristobal Perez, Juan C Lopez, Susana Blanco, Melanie Schnell. Water-induced structural changes in crown ethers from broadband rotational spectroscopy. The Journal of Physical Chemistry Letters, 7(20), 2016, 4053-4058.
48. Daike Li, Xinmin Gan, Minyu Tan, Xin Wang. Synthesis and characterization of lanthanide complexes of 1,4,7,10,13-pentaazacyclopentadecane, Polyhedron, 16(23), 3991-3995, 1997.
49. Kazuo Nakamoto. Infrared and Raman Spectra of Inorganic and Coordination Compounds.3rd Ed, John Wiley, New York, 1978
50. Dennis J Olszanski, Gordon A Melson. Inorganic chemistry of scandium. X. Macrocyclic polyether complexes of scandium (III). Inorganica Chimica Acta, 26, 1978, 263-269.
51. Harris PK, Mann BE, NMR and the Periodic Table, Academic Press, London, 1978
52. Stoss S, Schroth W, Kleinpeter E. Stereochemistry of crown ethers.V.-Solution structure and complexation behavior of dibenzo crown ethers. Magnetic Resonance in Chemistry, 30(5), 1992, 425-433.
53. Ines Starke, Andreas Koch, Erhard Uhlemann, Erich Kleinpeter. Nuclear magnetic resonance studies and molecular modeling of the solution structure of some dibenzo crown ethers and their complexes. Journal of Molecular Structure. 351, 1995, 165-179.
54. M Saiful Islam, Richard A Pethrick, Mark J Wilson. Theoretical study of the substituent effects of 4-substituted monobenzo crown ethers and the effects of ring size of 3n-crown-n (n=4-7) ethers on the cation selectivity. Journal of the Chemical Society, Faraday Transactions. 93(3), 1997, 387-392.
55. Haddadi H, Alizadeh N, Shamsipur M, Asfari Z, Lippolis V, Bazzicalupi C. Cation-π interaction in complex formation between Tl+ ion and calix[4] biscrown-6 derivatives: Thallium-203 NMR, proton NMR and X...Inorganic Chemistry, 49 (15), 2010, 6874-6882.
56. Wilson MJ, Pethrick RA, Pugh D, Islam MS. Nuclear magnetic resonance and ab initio theoretical studies of 18-crown-6, benzo- and dibenzo-18-crown-6 and their alkali-metal complexes. Journal of the Chemical Society, Faraday Transactions, 93(11), 1997, 2097-2104.
57. Mojtaba Shamsipur, Mohsen Irandoust. A proton NMR study of the stoichiometry and stability of 18-crown-6 complexes with K+, Rb+ and Tl+ ions in binary dimethyl sulfoxide-nitrobenzene mixture. Journal of Solution Chemistry. 37(5), 2008, 657-664
58. Bronislaw P Czech, Dhimant H Desai, Jacek Koszuk, Anna Czech, David A Babb, Thomas W Robison, Richard A Bartsch. Synthesis of lipophilic crown ethers with pendant phosphoric acid monoethyl ester groups. Journal of Heterocyclic Chemistry. 29(4), 1992, 867-875.
59. Gregory R Fulmer, Alexander JM Miller, Nathaniel H Sherden, Hugo E Gottlieb, Abraham Nudelman, Brian M Stoltz, John E Bercaw, Karen I Goldberg. NMR chemical shifts of trace impurities: common laboratory solvents, organics, and gases in deuterated solvents relevant to the organometallic chemist, Organometallics, 29(9), 2010, 2176-2179.
60. Alexander Higelin, Christoph Haber, Stefan Meier, Ingo Krossing, Isolated cationic crown ether complexes of gallium(I) and indium(I), Dalton Transactions, 41(39), 2012, 12011-12015.
61. Rajeev Ranjan, Poonam Bhardwaj, Seema Chitlangia and Jitesh Kumar Nayak. Synthesis and characterization of some crown ether complexes of Tl(I) ion. Asian Journal of Research in Chemistry, 9 (5), 2016, 212-216.
62. Hamaed H, Johnston KE, Cooper BFT, Terskikh VV, Ye E, Macdonald CLB, Arnold DC, Schurko RW. A 115In solid-state NMR study of low oxidation-state indium complexes. Chemical Science, 5, 2014, 982-995.
Received on 25.02.2020 Modified on 27.02.2020
Accepted on 29.02.2020 ©AJRC All right reserved
Asian J. Research Chem. 2020; 13(2): 91-96.
DOI: 10.5958/0974-4150.2020.00019.X