Synthesis, optical and electrochemical properties of new receptors and sensors containing anthraquinone and benzimidazole units

Novel anion receptors and sensors, HBIMANQ and BIMANQ fabricated from the imidazolole unit and anthraquinone moieties were synthesized. ¹H NMR spectroscopy and UV-vis titrations in DMSO-d₆ and DMSO, respectively, showed that both receptors underwent deprotonation at the NH- moiety of the amide-anthraquinone unit in the presence of basic anions such as F⁻ and AcO⁻. These phenomena gave a dramatic color change due to charge transfer transition corresponding to the shift of λ_max from 371 nm to 489 nm. Redox chemistry of HBIMANQ and BIMANQ in the presence of anions (F⁻, Cl⁻, AcO⁻, BzO⁻, and H₂PO₄⁻) using cyclic voltammetry showed the different CV responses upon addition of various anions. In the case of HBIMANQ with various anions, the CV changes are dependent on the basic strength of anions in order of F⁻>AcO⁻, BzO⁻>H₂PO₄⁻>Cl⁻, Br⁻. Interestingly, the CV responses of BIMANQ with H₂PO₄⁻ exhibited the most significant changes. BIMANQ, thus, has an excellent electrochemical selectivity toward H₂PO₄⁻.     

New P-bridgehead urea-based tripodal anion receptors for H2PO4 recognition

A series of new P-bridgehead tripodal urea-based anion receptors 1-3 bearing phosphine oxide (PO) were synthesized and characterized. Their anion-binding ability was examined by UV-vis, ¹H NMR, ³¹P NMR, and ESI-MS. The results revealed that receptors 1-3 showed good sensitivity, selectivity, and binding affinity for H₂PO₄⁻ over NO₃⁻ and Br⁻, and among them receptor 2 showed the best binding affinity for H₂PO₄⁻ over F⁻, Br⁻, CH₃COO⁻, HSO₄⁻, and NO₃⁻. The Job plot experiments indicated that receptors 1-3 formed 1:1 stoichiometric complex with H₂PO₄⁻.     

Anion recognition through hydrogen bonding by adamantane-dipyrromethane receptors

Adamantane-dipyrromethane (AdD) receptors [di(pyrrole-2-yl)methyladamantane (1), 2,2-di(pyrrole-2-yl)adamantane (2), 1,3-bis[di(pyrrole-2-yl)methyl]adamantane (3), 2,2,6,6-tetra(pyrrole-2-yl)adamantane (4)] form complexes with F⁻, Cl⁻, Br⁻, AcO⁻, NO₃⁻, HSO₄⁻, and H₂PO₄⁻. The association constants of the complexes were determined by ¹H NMR titrations, whereas the geometries of complexes 1·F⁻ (2:1), 2·F⁻ (2:1), 2·Cl⁻ (2:1), 2·AcO⁻ (2:1), and 4·F⁻ (1:1) were determined by X-ray structural analysis. The most stable complexes are of 2:1 stoichiometry with F⁻ and AcO⁻. The stability constants are in accordance with the anion basicity and the ability of AdD receptors to place the hydrogen bonding donor groups in a tetrahedral fashion around anions. The binding energies of the complexes between receptors 1-4 and F⁻ anion are calculated using quantum chemical methods. The calculated results show that the solvent polarity is important for the complexation of fluoride ion with AdD receptors 1-4.     

Fluoride-induced intermolecular excimer formation of bispyrenyl thioureas linked by polyethylene glycol chains

New bispyrenyl thioureas linked by polyethylene glycol (PEG) chains, L1-L3, and methoxy benzene pyrene thiourea, L4, were synthesized. Upon binding with F⁻ in CHCl₃, L1-L3 exhibited strong excimer emission bands (I_E) and weak monomer emission bands (I_M), while L4 displayed the same intensity of both bands. However, little or no change was observed in fluorescence spectra of L1 upon adding OH⁻, AcO⁻, BzO⁻, H₂PO₄⁻, Cl⁻, Br⁻, and I⁻. Therefore, only F⁻ induced the pyrene excimer formation. Job’s plots showed 1/1 or 2/2 complexation of L1 with F⁻. Ratios of I_E/I_M of L1·F⁻ complex were dependent on the concentration of L1, implying that the dimerization of L1 proceeded via the intermolecular excimer formation. Among L1-L4, L1 possessed the highest binding constant and sensitivity toward F⁻ implying the importance of the linking PEG chain. L1 was demonstrated to be an excellent probe for F⁻ in CHCl₃ with the detection limit as low as 46.2 μg/L.     

Calix[4]arenes containing urea and crown/urea moieties: effects of the crown ether unit and Na towards anion binding ability

Calix[4]arenes containing urea and crown/urea moieties, 7 and 10, respectively have been synthesized. ¹H NMR titrations of 7 and 10 with anions in DMSO-d₆ showed that 7 and 10 formed complexes with Cl⁻, Br⁻, NO₃⁻ and H₂PO₄⁻ to a different extent. The association constants of 7 and 10 towards anions were calculated and found to vary as H₂PO₄⁻>Cl⁻>Br⁻>NO₃⁻. However, compared to 7 the presence of the crown unit in 10 resulted in a slightly higher affinity to Cl⁻ and Br⁻, but a lower affinity to H₂PO₄⁻. Upon addition of Na⁺, the binding ability of 10 towards H₂PO₄⁻ is increased due to ion-pair enhancement.     

Anion recognition by 2,2′-binaphthalene derivatives bearing urea and thiourea groups at 8- and 8′-positions by UV-vis and fluorescence spectroscopies

Synthesis and anion recognition properties of 2,2′-binaphthalene derivatives bearing two thiourea (1) and urea (2) groups at 8- and 8′-positions were studied. The structure of receptor 1 was determined by X-ray crystallography. UV-vis spectra of the receptors showed characteristic changes around 300-400 nm through isosbestic points upon the addition of biologically relevant anions such as acetate, dihydrogenphosphate, and chloride in MeCN and DMSO due to restriction of the rotation around the single bond connecting two naphthyl moieties by cooperative guest binding of two recognition sites. Job’s plots showed 1:1 complexation for guest anions. The fluorescence quantum yields of free form of 1 and 2 in MeCN were determined to be 0.021 and 0.57, respectively. The fluorescence intensities of the receptors diminished upon the addition of anions in MeCN. The association constants of receptors 1 and 2 were one or two orders of magnitude greater than the corresponding monothiourea and urea receptors 3 and 4 indicating cooperative hydrogen bonding with guest anions. The selectivity trends of association of anions were F⁻>AcO⁻>H₂PO₄⁻>Cl⁻>>HSO₄⁻≈NO₃⁻≈Br⁻≈I⁻ for 1, and F⁻>AcO⁻≈Cl⁻>H₂PO₄⁻>Br⁻>HSO₄⁻>I⁻≈NO₃⁻ for 2. Receptor 2 showed remarkable Cl⁻ selectivity presumably owing to suitable orientation for effective hydrogen bond formation with Cl⁻.     

Urea and thiourea based efficient colorimetric sensors for oxyanions

Urea and thiourea based receptors 1 and 2 bind H₂PO₄⁻, OH⁻, CH₃CO₂⁻, and PhCO₂⁻ ions in an acetonitrile/DMSO (9:1, v/v) medium. Binding of these anions causes an appreciable change in the visible region of the spectrum, which can be detected by the naked eye. The affinity constant for H₂PO₄⁻ is higher by about an order of magnitude as compared to the other oxyanions mentioned above. Ab initio calculations predicted tweezer-like binding modes for receptors 1 and 2 with these anions and a higher affinity toward H₂PO₄⁻ was predicted in acetonitrile.     

Synthesis,spectroscopic and crystal structure investigation of [Cu(bzsmp)2Cl2];{bzsmp = 2-benzylsulfanyl-5-(2-methoxyphenyl)-1,3,4-oxadiazole}: cyclization of N-[bis(benzylsulfanyl)methylene]-2-methoxybenzohydrazide to 2-benzylsulfanyl-5-(2-methoxyphenyl)-1,3,4 -oxadiazole during complexation

The ligand N²-[bis(benzylsulfanyl)methylene]-2-methoxybenzohydrazide (N²-bmbh) (1) on reaction with CuCl₂.2H₂O yielded the mononuclear complex [Cu(bzsmp)₂Cl₂] (2) (2-benzylsulfanyl-5-(2-methoxyphenyl)-1,3,4-oxadiazole, bzsmp). Complex 2 has been characterized by analytical, spectroscopic and X-ray data. X-ray study of 2 reveals that the cyclized ligand 2-benzylsulfanyl-5-(2-methoxyphenyl)-1,3,4-oxadiazole (bzsmp) acts as neutral bidentate ligand to form six membered chelate ring and the presence of C–H?π (face to edge) and C–H?S and two type of C–H?Cl weak interactions.     

Naked eye sensing of anions using thiourea based chemosensors with real time application

Novel chromogenic sensors with thiourea moiety as receptor unit were synthesized and characterized using IR and NMR spectroscopic techniques. The receptors 1 and 2 bearing hydrogen bonding site demonstrate visually striking color change, UV–vis, and fluorescence responses for F⁻, AcO⁻, and OH⁻ over other anions such as Cl⁻, Br⁻, H₂PO₄⁻ and HSO₄⁻. Both the receptors 1 and 2 demonstrate detection limit at micro molar level. Further insight to the nature of interaction between receptors and anions was studied using ¹H NMR titration experiment. In particular, the fluoride of tooth paste and mouthwash in water phase can be detected by receptor 2.     

Hydrothermal synthesis and characterization of the first 1-D indiumphosphate chain In2(HPO4)2(H2PO4)2F2·C4N2H12, a precursor for high dimensional structures

The first one-dimensional (1-D) indiumphosphate chain, In₂(HPO₄)₂(H₂PO₄)₂F₂·C₄N₂H₁₂ (1), has been hydrothermally prepared using piperazine (PIP) as a template. The structure consists of infinite chains of trans,trans-corners-sharing InO₄F₂ octahedra with the adjacent octahedra being bridged by tetrahedral PO₃(OH) and PO₂(OH)₂ units, which are H-bonded with amine groups of the organic cations. Interestingly, this macroanionic chain InP₂O₈H₃F⁻ is similar to that found in the mineral tancoite-like chains and has potential to further set up higher-dimensional networks. On heating 1 in the presence of additional phosphoric acid at 180 °C under hydrothermal condition, compound 2, In₂(OH)(H₂O)(PO₄)₂·H₃O·H₂O, possessed a 3-D structure building from the repetition of a secondary building unit is obtained. When 1 is heated with additional PIP, an unknown phase, compound 3 is formed. Finally, on treatment with another amine, such as diethylenetriamine or 1,4-diaminobutane, at 180 °C, 1, as a precursor, can convert into a previously known 3-D framework structure with 16-membered ring compound 4. Compounds 1 and 2 are determined by single-crystal X-ray diffraction. Furthermore, 1 is characterized by X-ray powder diffraction, IR spectroscopy, inductively coupled plasma analysis, thermogravimetric analysis and differential thermal analysis.     

[1,1-Bis(diphenylphosphino)ferrocene]palladium(II) complexes with fluorinated benzenethiolate ligands: examination of the electronic effects in the solid state, solution and in the Pd-catalyzed Heck reaction with the catalytic system [Pd(dppf)(SRF)2]

A series of palladium thiolate complexes of the type [Pd(dppf)(SR_F)₂] have been synthesized in good yields by metathetical reactions of [Pd(dppf)Cl₂] with [Pb(SR_F)₂], (SR_F=⁻SC₆F₅, ⁻SC₆F₄-4-H, ⁻SC₆H₄-2-CF₃, ⁻SC₆H₄-4-F, ⁻SC₆H₄-3-F) and their crystal structures determined. The effect of the different thiolates in the structural properties of the complexes both in the solid state and in solution have been analyzed. Heck coupling reactions were carried out using the complexes [Pd(dppf)(SR_F)₂], SR_F=⁻SC₆F₅ (1), ⁻SC₆F₄-4-H (2), ⁻SC₆H₄-2-CF₃ (3), ⁻SC₆H₄-4-F (4), ⁻SC₆H₄-3-F (5) as catalysts in order to examine both the effect of the thiolates and the P-Pd-P bite angles in the reaction of bromobenzene and styrene. The results obtained indicate that electron-withdrawing substituents may favor higher yields in the Pd catalyzed Heck reaction using [Pd(dppf)(SR_F)₂] as catalysts.     

Transition metal cyclopentadienyl complexes bearing perfluoro-4-tolyl substituents

Depending on the ratio of starting materials and the reaction conditions, perfluorotoluene (C₆F₅CF₃) reacts with sodium cyclopentadienide (NaCp; Cp = C₅H₅) and excess sodium hydride to afford, after acidic aqueous workup, moderate to high yields of mono-, bis-, tris-, and tetrakis(perfluoro-4-tolyl)cyclopentadiene (1, 2, 3, and 4, respectively). Treatment of 1 with excess NaH in THF afforded sodium (perfluoro-4-tolyl)cyclopentadienide (5) in 90% yield. Reaction of FeBr₂ with 2 equiv. of 5 afforded a 68% yield of (η⁵-C₅H₄C₇F₇)₂Fe (6). Reaction of ZrCl₄(THF)₂ with 2 equiv. of 5 afforded a 58% yield of (η⁵-C₇F₇C₅H₄)₂ZrCl₂ (7). Reaction of Mn(CO)₅Br with 5 afforded a 74% yield of (η⁵-C₇F₇C₅H₄)Mn(CO)₃ (8). Treatment of 3b with NaH and then with Mn(CO)₅Br in DME afforded a 26% yield of [η⁵-1,2,4-(C₇F₇)₃C₅H₂]Mn(CO)₃ (9). Treatment of 3b with NaH and then with FeBr₂ in DME afforded a trace yield of [η⁵-1,2,4-(C₇F₇)₃C₅H₂]₂Fe (10), which was not fully characterized. Dienes 2a, 3a, and 3b and metal complexes 7, 8, and 9 were structurally characterized by single-crystal X-ray diffraction. Infrared spectroscopic analysis of the substituted CpMn(CO)₃ complexes showed a linear increase of 5 cm⁻¹ in the A-symmteric stretching frequency for each C₇F₇ substituent, compared to the analogous value of 4 cm⁻¹ reported earlier for each pentafluorophenyl (C₆F₅) substituent. Solution voltammetric analysis of the substituted ferrocene 6 revealed a shift in the E_1/2 of 465 mV relative to ferrocene, compared to the analogous value of about 340 mV for 1,1′-bis(pentafluorophenyl)ferrocene.     

Synthesis and properties of novel 5-(cyclohepta-2′,4′,6′-trienylidene)pyrimidine-2(1H),4(3H),6(5H)-triones: methodology for synthesizing cyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dionylium tetrafluoroborates

Novel condensation reaction of tropone with N-substituted and N,N′-disubstitued barbituric acids in Ac₂O afforded 5-(cyclohepta-2′,4′,6′-trienylidene)pyrimidine-2(1H),4(3H),6(5H)-trione derivatives (8a-f) in moderate to good yields. The ¹³C NMR spectral study of 8a-f revealed that the contribution of zwitterionic resonance structures is less important as compared with that of 8,8-dicyanoheptafulvene. The rotational barriers (ΔG^‡) around the exocyclic double bond of mono-substituted derivatives 8a-c were obtained to be 14.51-15.03 kcal mol⁻¹ by the variable temperature ¹H NMR measurements. The electrochemical properties of 8a-f were also studied by CV measurement. Upon treatment with DDQ, 8a-c underwent oxidative cyclization to give two products, 7 and 9-substituted cyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dionylium tetrafluoroborates (11a-c·BF₄⁻ and 12a-c·BF₄⁻) in various ratios, while that of disubstituted derivatives 8d-f afforded 7,9-disubstituted cyclohepta[b]pyrimido[5,4-d]furan-8(7H),10(9H)-dionylium tetrafluoroborate (11d-f·BF₄⁻) in good yields. Similarly, preparation of known 5-(1′-oxocycloheptatrien-2′-yl)-pyrimidine-2(1H),4(3H),6(5H)-trione derivatives (14a-d) and novel derivatives 14e,f was carried out. Treatment of 14a-c with aq. HBF₄/Ac₂O afforded two kinds of novel products 11a-c·BF₄⁻ and 12a,c·BF₄⁻ in various ratios, respectively, while that of 14d-f afforded 11d-f. The product ratios of 11a-c·BF₄⁻ and 12a-c·BF₄⁻ observed in two kinds of cyclization reactions were rationalized on the basis of MO calculations of model compounds 20a and 21a. The spectroscopic and electrochemical properties of 11a-f·BF₄⁻ and 12a-c·BF₄⁻ were studied, and structural characterization of 11c·BF₄⁻ based on the X-ray crystal analysis and MO calculation was also performed.     

Macrocyclic bis(amidonaphthol)s for anion sensing: tunable selectivity by ring size in proton transfer process

The investigation on anion sensing properties for a series of macrocyclic bis(amidonaphthol)s 3a-3c reveals the significant effects of macrocyclic ring size. Among them, macrocycle 3c with the largest ring size shows F⁻ ion selectivity by causing clear red shift (24 nm) in fluorescence emission after complexation with F⁻, which results in significant color change of fluorescence from blue to green. This excellent selectivity toward F⁻ ion might be attributed to the fitness between the acidity of -OH group and the basicity of F⁻ ion. Further exploration indicates that the acidity of -OH group can be tuned by ring size to give it the capability to discriminate the subtle difference in the affinity of F⁻, CH₃COO⁻, and H₂PO₄⁻ to -OH proton.     

Iron,copper and zinc ammonium-1-hydroxyalkylidene-diphosphonates with zero-, one- and two-dimensional covalent metal–ligand structures extended into three-dimensional supramolecular networks by charge-assisted hydrogen-bonding

Hydrothermal synthesis with MCl₂ (M = Fe, Cu, and Zn) and disodium 5-ammonium-1-hydroxypentylidene-1,1-bisphosphonate, (Na⁺)₂[⁺H₃N(CH₂)₄C(OH)(PO₃²⁻)(PO₃H⁻)] (Na₂HAC₅OHP₂) or sodium 3-ammonium-1-hydroxypropylidene-1,1-bisphosphonate hydrate, Na⁺[⁺H₃N(CH₂)₂C(OH)(PO₃H^–)(PO₃H^–)]·H₂O (NaH₂PAM·H₂O) the sodium salt of pamidronic acid, H₃PAM) yielded the one-dimensional (1D) iron, molecular copper and two-dimensional (2D) zinc compounds 1D-{[Fe(μ₃-η⁵-HAC₅OHP₂)]·H₂O}, 1, [Cu(η²-H₂AC₅OHP₂)₂], 2, 2D-{[Zn₂(μ₅-η⁷-AC₅OHP₂)Cl], 3, and 2D-{[Zn(μ₂-η³-H₂PAM)₂], 4, respectively. The bisphosphonate ligand bridges (μ_n) between 2–5 metal atoms and uses 2–7 oxygen donor atoms towards metal coordination (ηⁿ). The zwitterionic nature of the now bis- or tetrakis-deprotonated ammonium–bisphosphonate is retained in the metal complexes. From the reaction of NiCl₂ and Na₂HAC₅OHP₂ the zwitterionic 5-ammonium-1-hydroxypentylidene-1-phosphonic acid, ⁺H₃N(CH₂)₄CH(OH)PO₃H⁻, 5 was obtained as a product of the ligand P–C bond hydrolysis. Adjacent strands, molecules or layers in 1–4, respectively are organized through the Coulomb attraction between the positive ammonium group and the negative phosphonate groups, supported by hydrogen-bonding. Each protic H atom on the C–OH, NH₃⁺ and –PO₃H⁻ group is involved in charge-assisted hydrogen-bonding. The ammonium-pentylidene groups act as hydrophobic separators between the hydrophilic units with the polar M{C(OH)(PO₃)₂} and {NH₃} units. Bond valence sum calculations support the Fe(II) oxidation state in 1, which was experimentally determined from a quantitative polarographic Fe(II)/Fe(III) speciation analysis as well as a temperature variable magnetic study.     

Fluorescent sensor based on dimesitylborylthiophene derivative for probing fluoride and cyanide

A new D-π-A dimesitylboron derivative with terminal phenothiazine bridged by fluorenevinyl (PFTB) has been synthesized. It was found that PFTB could selectively recognize fluoride and cyanide anions by naked eyes. Upon addition of F⁻ and CN⁻, the color of the solution of PFTB in DCM turned to yellowish-green from yellow and strong green emitting was observed under UV light, while the emission of PFTB in DCM was weak. Moreover, the presence of 10 equiv of tetrabutylammonium salts of other anions, such as Cl⁻, Br⁻, I⁻, AcO⁻, HSO₄⁻, H₂PO₄⁻, could not lead to obvious changes of the UV–vis absorption and the fluorescent emission spectra of PFTB. The detection limits of PFTB towards F⁻ and CN⁻ were 7.52×10⁻⁸ mol/L and 6.12×10⁻⁸ mol/L in DCM, respectively. Therefore, the D-π-A type triarylborane derivatives can be used as ‘turn on’ fluorescent sensors for detecting F⁻ and CN⁻.     

Ion pair symmetrization in metallocenium cations partnered with diborane derived borate counteranions

The thermodynamics of ion pair symmetrization in a series of metallocenium species generated from were studied using a variety of solution dynamic techniques including line broadening, 2D-EXSY, and 1D-DPFGSE-NOE. Ion pairs were generated by methide abstraction using the corresponding trityl salts [1-A] to yield (A = {C₆F₄-1,2-[B(C₆F₅)₂]₂(μ-O(C₆F₅))}⁻, 2-O(C₆F₅); {C₆F₄-1,2-[B(C₆F₅)₂]₂(μ-OPh)}⁻, 2-OPh; {C₆F₄-1,2-[B(C₆F₅)₂]₂(μ-OMe)}⁻, 2-OMe; and [B(C₆F₅)₄]⁻, 2-B(C₆F₅)₄). The observed activation parameters were interpreted on the basis of a solvent-assisted mechanism of ion pair symmetrization.     

The preparation of [closo-1-CB9H8-1-COOH-10-(4-C3H7C5H9S)] as intermediate to polar liquid crystals

The preparation of iodo acid [closo-1-CB₉H₈-1-COOH-10-I]⁻ (1) is optimized and scaled from 1 to 40 g of B₁₀H₁₄. The improved preparation of the [arachno-6-CB₉H₁₃-6-COOH]⁻ (5) uses four times smaller volume and can be run conveniently in up to 40 g scale in a 3-L vessel. The optimized oxidation of 5 to [closo-2-CB₉H₉-2-COOH]⁻ (4) requires less oxidant, 12 times smaller volume, and significantly shorter reaction time. The overall yields of the iodo acid 1 as the [NMe₄]⁺ salt are typically 8-10% (10-12 g) for 40 g of B₁₀H₁₄. The iodo acid 1 was transformed to amino acid 8, then to dinitrogen acid 10, and finally to sulfonium acid 2[3] in overall yield of about 13%. The search for a more efficient phosphine ligand for the Pd-catalyzed amination process was not fruitful. Three routes to the sulfonium acid 2[n] were investigated, and the best yield of about 47% was obtained for Cs₂CO₃-assisted cycloalkylation. Liquid crystalline ester of acid 2[3] and 4-butoxyphenol was prepared and investigated.     

Colorimetric response of spiropyran derivative for anions in aqueous or organic media

We previously found that a simple spiropyran derivative (1:1′,3′,3′-trimethyl-6-nitro-spiro-[2H-1-benzopyran-2,2′-indoline]) behaves as a selective and sensitive cyanide anion (CN⁻) receptor in aqueous media under UV irradiation¹³. The receptor, when irradiated by UV light in a water/MeCN mixture, creates a CN⁻-selective absorption band via a nucleophilic addition of CN⁻ to 1 (formation of the 1-CN⁻ species) and allows quantitative determination of very low levels of CN⁻. In the present work, effects of pH and water content on the response of 1 to anions were studied to clarify the detailed properties of 1. In aqueous media, 1 reacts selectively with CN⁻regardless of pH and water content, but the reaction is suppressed by a decrease in pH and an increase in water content due to the protonation of CN⁻. In contrast, in pure MeCN, addition of F⁻ also creates a new absorption band, as does CN⁻. This is promoted via a nucleophilic interaction between 1 and F⁻ in a 1:2 stoichiometry (formation of the 1-2F⁻ species). The 1-CN⁻ and 1-2F⁻ species have different photochemical properties; the 1-CN⁻ species is stable upon UV irradiation, while the UV irradiation of the 1-2F⁻ species leads to a decomposition of the spiropyran platform.     

Synthesis and anion binding properties of new dihomooxacalix[4]arene diurea and dithiourea receptors

Functionalization of the lower rim of p-tert-butyldihomooxacalix[4]arene with two (thio)ureido moieties provided new diurea (n-propyl 5a, tert-butyl 5b and phenyl 5c) and dithiourea (phenyl 5d) derivatives, all in the cone conformation, as shown by NMR studies. The X-ray crystal structure of 5c is reported. The binding ability of these neutral receptors towards a large variety of anions was assessed by ¹H NMR titrations. The structures and complexation energies of some complexes were also studied using DFT methods. The data showed that, in general, the association constants decrease with decrease of anion basicity and they are strongly dependent on the nature of the substituent at the urea moiety. Phenyl-(thio)urea derivatives 5c and 5d are the best anion receptors, showing the strongest complexation for F⁻ (log K_ass=2.70 and 2.75, respectively) and also for the oxoanions AcO⁻, BzO⁻ and H₂₄PO⁻${{\text{H}}_2{\text{PO}}_4}^{-}$. These results were corroborated by DFT calculations.