Solid Complexes Research Articles

Complex Formation of Europium(III) with Photoditazine According to Luminescence and IR Spectroscopy

Europium(III) complexation with photoditazine, a photosensitizer for photodynamic therapy, was studied using luminescence and IR spectroscopy. The luminescence spectra of europium–photoditazine solutions and solid complex show emission bands in the 400–700 nm range, typical of both Eu3+ complexes and photoditazine. It was shown that Eu3+ luminescence intensity in the red region increases upon complex formation with photoditazine. Since the luminescence bands of solutions at 400–700 nm overlap with photoditazine absorption bands, the addition of europium chloride enhances the excitation energy transfer to photoditazine. A medication comprising a europium salt and photoditazine as a photosensitizer could serve for the targeted delivery of light radiation to photoditazine at UV excitation, which would result in more efficient formation of reactive oxygen species and can be promising for external photodynamic therapy.

Spin-crossover in iron(II)-phenylene ethynylene-2,6-di(pyrazol-1-yl) pyridine hybrids: toward switchable molecular wire-like architectures

Luminescent oligo(p-phenylene ethynylene) (OPE) and spin-crossover (SCO) active Fe(II)-2,6-di(pyrazol-1-yl) pyridine (BPP) systems are prominent examples proposed to develop functional materials such as molecular wires/memories. A marriage between OPE and Fe(II)-BPP systems is a strategy to obtain supramolecular luminescent ligands capable of metal coordination useful to produce novel spin-switchable hybrids with synergistic coupling between spin-state of Fe(II) and a physical property associated with the OPE skeleton, for example, electronic conductivity or luminescence. To begin in this direction, two novel ditopic ligands, namely L1 and L2, featuring OPE-type backbone end-capped with metal coordinating BPP were designed and synthetized. The ligand L2 tailored with 2-ethylhexyloxy chains at the 2 and 5 positions of the OPE skeleton shows modulated optical properties and improved solubility in common organic solvents relative to the parent ligand L1. Solution phase complexation of L1 and L2 with Fe(BF4)2·6H2O resulted in the formation of insoluble materials of the composition [Fe(L1)]n(BF4)2n and [Fe(L2)]n(BF4)2n as inferred from elemental analyses. Complex [Fe(L1)]n(BF4)2n underwent thermal SCO centred at T1/2 = 275 K as well as photoinduced low-spin to high-spin transition with the existence of the metastable high-spin state up to 52 K. On the other hand, complex [Fe(L2)]n(BF4)2n, tethered with 2-ethylhexyloxy groups, showed gradual and half-complete SCO with 50% of the Fe(II)-centres permanently blocked in the high-spin state due to intermolecular steric interactions. The small angle x-ray scattering (SAXS) pattern of the as-prepared solid complex [Fe(L1)]n(BF4)2n revealed the presence of nm-sized crystallites implying a possible methodology towards the template-free synthesis of functional-SCO nanostructures.

Copper(II) complexes of aroylhydrazones: Preparation and structural characterization

Structures of solid copper complexes with aroylhydrazones obtained from nicotinic acid hydrazide and salicylaldehyde derivatives differing in substituents on the benzene ring were analysed by means of infrared (IR) and Raman spectroscopy. Studied aromatic hydrazones acted as neutral, monoanionic or dianionic tridentate ligands, depending on the tautomer form adopted during the complexation process. Various additional substituents on the salicylaldehyde originated ring were not involved in metal coordination, thus carbonyl/enolic oxygen, azomethine nitrogen and oxygen of the phenolic hydroxyl group were proposed as the coordination sites for the copper(II) ion. In all applied synthesis conditions Cu(II) complexes were obtained in Cu(II)/hydrazone molar ratio of 1/1, except for a hydrazone with nitro group, which did not form a complex with Cu(II) regardless of the synthetic conditions. Vibrational spectra indicated that hydrazone having only ortho-hydroxyl group with respect to the double CN bond as well as a hydrazone with an additional OH group in para-position on the benzene ring, formed monomeric copper(II) complexes including water as a ligand, while hydrazones with meta-substituents (Cl, OCH3) formed binuclear copper complexes, in which two copper(II) ions bridge hydrazone molecules via phenolic oxygen atom. Thermal properties of prepared copper(II) complexes were investigated by means of thermogravimetric analysis.

Heightening the solubility of poorly soluble fenofibrate by Solid Dispersion Technique

The intention of the current study was to boost the solubility of Fenofibrate by solid dispersion technique which is an efficient technique in improving the solubility and hence the dissolution rate of poorly soluble drugs in the form of eutectic mixtures by producing fine dispersion when in contact with gastrointestinal fluid and also the technique offers the choices of carriers to be combined with drug conveniently to improve the solubility to a considerable extent. Fenofibrate a BCS class II Antihyperlipidemic drug belongs to fibrate class and it is a lipid-lowering drug used in the treatment of hyperlipidemia. Fenofibrate is insoluble in water and hence shows poor dissolution in gastric fluid with reduced absorption characteristics. In order to improve the solubility, dissolution rate, gastrointestinal absorption and oral bioavailability, it was decided to prepare fenofibrate solid dispersion and evaluated. They were prepared using poly ethylene glycol 4000, 6000, 8000 and β-cyclodextrin by fusion technique and optimized solid dispersion was also lyophilized. Physical characterization of solid inclusion complex of fenofibrate was studied and showed that there were no drug excipients interactions. Dissolution studies showed a momentous rise in a dissolution of Fenofibrate when dispersed in polymers. Inturn aqueous solubility was enlarged linearly as a function of the concentration of β- Cyclodextrin.

The structure and composition of solid complexes comprising of Nd(III), Ca(II) and D-gluconate isolated from solutions relevant to radioactive waste disposal

Abstract Certain complexing agents (such as D-gluconate, D-isosaccharinate, etc.) as well as actinides and lanthanides are simultaneously present in cementitious radioactive waste repositories and (in the presence of water) are capable of forming complex compounds. Such processes may immobilize radionuclides and are of importance in the thermodynamic modelling of the aqueous chemistry of waste repositories. Nd(III) is considered to be a suitable model for trivalent lanthanides and actinides, due to the similarity of their ionic radii. In the current work, solid complexes isolated from aqueous solution containing Nd(III), Ca(II) and D-gluconate (Gluc−) were investigated. In an aqueous solution containing Nd(III) and Gluc−, the formation of a precipitate was observed at pH ≥ 8. This precipitate was found to redissolve around pH ~ 11, but reprecipitated when Ca(II) ions were added to the solution. In order to gain an insight in binary and ternary aqueous systems, in the present work we report the structure of these solid complexes obtained from XRD, FT-IR, Raman, SEM-EDAX and UV-DRS measurements. The structure of these solids, where possible, was compared with those identified in solution. The compositions of these complexes are suggested to be NdGlucH−1(OH) · 2H2O and CaNdGlucH−1(OH)3 · 2H2O, respectively. In these, the chemical environment of the Nd(III) was found to be the same as that in the NdGlucH−1(OH)0(aq) solution species.

Measurements and calculations of solid-liquid equilibria in two quaternary systems: LiCl–NaCl–SrCl2–H2O and LiCl–KCl–SrCl2–H2O at 298 K

Using the method of isothermal dissolution equilibrium, stable phase equilibria of unreported strontium-containing systems LiCl–NaCl–SrCl2–H2O and LiCl–KCl–SrCl2–H2O at 298 K have been studied in accordance with the compositions of the underground brine in western Sichuan Basin. The experimental results show that there are no solid solution and complex salt in two quaternary systems. The phase diagram of quaternary system LiCl–NaCl–SrCl2–H2O consists of two invariant points, five isothermal dissolution curves and four crystallization regions. The quaternary system LiCl–KCl–SrCl2–H2O belongs to a simple type and the phase diagram consists of two invariant points, five isothermal dissolution curves and four crystallization regions. The solubilities of salts in the above systems were accurately calculated with Pitzer electrolyte solution theory. It was found that the calculated phase diagrams coincided basically with the experimental phase diagrams by evaluated the accuracy through the experimental results. Meanwhile, the applicability of Pitzer parameters selected in this paper was validated.

Chain length effect on the structure and thermotropic phase transitions of solid catanionic complexes built of cetyltrimethylammonium bromide and saturated n-fatty acids

Chain length effect on the structure and thermotropic properties of asymmetric solid catanionic complexes (CAC) built of cetyltrimethylammonium bromide (C16TABr) and saturated n-fatty acids (CnSFA, CnH2nO2, n = 12, 18, 20, and 22) was investigated by XRD, DSC, and FTIR spectroscopy. All CAC show a lamellar crystalline structure and a series of solid–solid phase transitions below the melting point. The phase transitions are suggested to be caused by sequential melting of the methylene chains in the hydrophobic layer followed by a change in the crystalline structure. C16TABr stabilizes the bilayer structure of CAC and raises its melting point compared to initial CnSFA.

Preparation ,Characterization and The Biological Activity Study of A new heterocyclic (Azo-Schiff base) ligand and Their Complexation with {Co,Ni,Cu,Zn(II)}Ions

A new tetra dentate Schiff base ligand has been synthesized from condensation of compound (1): [( 4 -((1-H-imidazol-2-yldiazenyl)-1,5-dimethyl-2-phenyl-1Hpyrazol-3(2H)-one)]with compound (2) thio semicarbazaide. The general formula of complexes are [M(L)]Cl2 Where. M= Co(II) ,Ni (II)and Cu(II)Zn(II) are reported. The geometry structures of ligand and the complexes were determined through Fourier-transform infrared spectroscopy (FT-IR), Mass spectra, X-ray diffraction analysis, Ultra violet-Visible(UV-Vis), Proton nuclear magnetic resonance(1H NMR) spectral studies, magnetic moment measurement, elemental analysis, and molar conductance. These studies revealed square planar geometries for Ni(II)and Co(II) and Cu(II)complexes, except the Zn(II) complex was a tetrahedral geometry around the central metal ion. Complex formation studies via molar ratio and continuous variation methods were consisted to those found in the solid complexes with a ratio of (M:L) as (1:1) . Stability constant of complexes were calculated by spectrophotometric methods. Hyper Chem-8 program has been used to predict geometries structures of compounds in gas phase. The heat of formation (∆Hf) and binding energy (∆E b) at 298 K for the metal complexes were calculated by PM3 method. Biological activity studies of the ligand and their metal complexes against several organisms, bacteria Gram positive G(+ve)staphylococcus aureus and bacteria Gram negative G(- ve)Escherichia coli, klebsiella pneumonic, In addition to fungi like Aspergillus Niger, Rhizoclonia bataicola and Aspergillus flavus , are reported. Compounds exhibited the high activity on the growth of all types microorganisms in this study. This may be attributed to the impact of both the chelate effect of Schiff bases ligand and the role of the metal in these complexes.

Spectroscopic Characterization, Molecular Modeling and DFT/TD-DFT/PCM Calculations of Novel Hydrogen-Bonded Charge Transfer Complex between Chloranilic Acid and 2-Amino-4,6-Dimethylpyridine

A charge transfer hydrogen bonded complex between the electron donor (proton acceptor) 2-amino-4,6-dimethylpyridine with the electron acceptor (proton donor) chloranilic acid has been synthesized and studied experimentally and theoretically. The stability constant recorded high values indicating the high stability of the formed complex. In chloroform, ethanol, methanol and acetonitrile were found the stoichiometric ratio 1:1. The solid complex was prepared and characterized by different spectroscopy techniques. FTIR, 1H and 13C NMR studies supported the presence of proton and charge transfers in the formed complex. Complemented with experimental results, molecular modelling using the density functional theory (DFT) calculations was carried out in the gas, chloroform and methanol phases where the existence of charge and hydrogen transfers. Finally, a good consistency between experimental and theoretical calculations was found confirming that the applied basis set is the suitable one for the system under investigation.

Synthesis, Characterization, Physicochemical Studies and Antimicrobial Evaluation of Mixed Ligand Complexes Involving Co(II) with 2,2′-Dipyridylamine and Dicarboxylic Acids

In the current research, the complex formation equilibria of 2,2′-dipyridylamine (DPA) with the metal ions Cu(II), Ni(II), Co(II), Mn(II), and Zn(II) are investigated potentiometrically. The relation between the stability constants of the formed complexes and the properties of the central metal ions was investigated. In addition, the solvent effect on the protonation of DPA and Co-DPA complex formation was also investigated and discussed. The formation of the ternary complexes Co(DPA)L (L = some selected dicarboxylic acids) was studied in aqueous solutions at 25 °C and 0.1 mol dm−3 ionic strength. Stability constants and stoichiometry are reported for the complexes formed in solution. The results show that ternary complexes are formed by a simultaneous reaction mechanism. The speciation of all the complexes was resolved. The effect of chelate ring size of the dicarboxylic acid complexes on their stability constants was also examined. The concentration distribution of the complexes in solution was evaluated. The solid complexes [Co(DPA)L] (where L is oxalic, malonic, succinic or 1,1-cyclobutanedicarboxylic (CBDC) acid) have been synthesized and fully characterized with the help of elemental analyses, infrared spectra, magnetic and conductance measurements. Spectroscopic studies and magnetic measurements (Meff) suggest a tetrahedral geometry for Co(II)-complexes. The measured molar conductance values in DMSO indicate that the complexes are nonelectrolytic in nature. The isolated solid complexes have also been screened for their pharmacological activities against some selected bacteria and fungi. The activity data show that the complexes have a significant activity against Escherichia coli (gram negative) and Staphylococcus aureus (gram positive), as well as an antifungal activity against Aspergillus flavus and Candida albicans.

Comparative Study of Etoricoxib Loaded Solid Dispersion and Beta-cyclodextrin Complexes for improvement of Dissolution Profile

Comparative Study of Etoricoxib Loaded Solid Dispersion and Beta-cyclodextrin Complexes for improvement of Dissolution Profile

ENHANCEMENT OF DISSOLUTION OF CILOSTAZOLE BY COMPLEXATION METHOD USING CYCLODEXTRINS

The study was designed to investigate the effect of cyclodextrins (CDs) on the solubility, dissolution rate, and bioavailability of cilostazol by forming inclusion complexes. Natural CDs like β-CD, γ-CD, and the hydrophilic β-CD derivatives, DM-β-CD and HP-β-CD, were used to prepare inclusion complexes with cilostazol. Phase solubility study was carried out and the stability constants were calculated assuming a 1:1 stoichiometry. Solid cilostazol complexes were prepared by coprecipitation and kneading methods and compared with physical mixtures of cilostazol and cyclodextrins. Prepared inclusion complexes were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) studies. In vitro dissolution study was performed using phosphate buffer pH 6.4, distilled water, and HCl buffer pH 1.2 as dissolution medium. The optimized inclusion complex was studied for its bioavailability in rabbit and the results were compared with those of pure cilostazol and Pletoz-50. Phase solubility study showed dramatic improvement in the solubility of drug by formation of complexes, which was  further increased by  pH  adjustment. The in vivo study revealed that DM-β-CD increased the bioavailability of cilostazol with low variability in the absorption. Among all cilostazol–cyclodextrins complexes, cilostazol–DM-β-CD inclusion complex (1:3) prepared by coprecipitation method showed 1.53-fold and 4.11-fold increase in absorption along with 2.1-fold and 2.97-fold increase in dissolution rate in comparison with Pletoz-50 and pure cilostazol, respectively.

Spectral Characterization, Thermal and Antimicrobial Studies of Some Divalent Metal Chelates of 7-((3-Phenyl-4,5-dihydroisoxazol-5-yl)methyl)quinolin-8-ol

A series of Cu(II), Ni(II) and Co(II) azo chelates (AZC1-AZC3) of 7-((3-phenyl-4,5-dihydroisoxazol-5-yl)methyl)quinolin-8-ol have been designed and obtained. Thermal measurements, molar conductance, magnetic moment, elemental analyses, spectral (IR, UV-Vis, 1H and 13C NMR, ESR, mass) were used to characterize insulated solid complexes. The metal complexes were assumed to be non-electrolytic by molar conductance values. Thermal properties and decomposition kinetics of the metal chelates are investigated using Coats-Redfern method. The kinetic parameters like activation energy (E*), pre-exponential factor (A) and entropy of activation (ΔS*) were quantified. Results of spectral studies of mass and TGA data confirmed the octahedral geometry for all chelates. Finally, the synthesized metalcomplexes were tested for their in vitro antimicrobial efficacy.

Electron and Mass Transfer during Solid Carbon Reduction of Metals in Solid Complex Oxides

The possibility of iron and chromium reduction in the composition of complex oxides by gaseous carbon monoxide and solid carbon was studied in a laboratory resistance furnace with a graphite heater. Holding only a CO atmosphere does not reduce chromium and iron in both chromites and silicates. In a mixture with solid carbon, chromium and iron were completely reduced in chromites, and iron precipitated in an iron–magnesia silicate matrix in the part having undergone hydration in nature and dehydration upon heating. Continuous carbide shells, which exactly reproduce a surface relief, appear on the surfaces of solid oxide and carbon in a mixture of solid reagents. Similar shells consisting of a carbon-free FeCr alloy form on the surfaces of chromite crystals disseminated in a silicate phase. These results do not correspond to the concepts of both direct and indirect reduction, and they are analyzed in terms of electronic reduction theory developed by us. According to this theory, a low-temperature plasma appears in a mixture of solid reagents due to thermionic electron emission from the carbon surface. As a result, charged particles, namely, electrons and carbon cations, appear near the reagent surfaces. Their interaction with oxide anions causes the formation of CO and anion vacancies, which are charged by two electrons and are scattered in the anion sublattice of oxide. The saturated vacancy solution in the anion sublattice of oxide decomposes to form anion void at the site where the chemical potential of free electrons reaches the Fermi level of certain cations. These cations in anion void regroup to form a metallic phase. The high reducibility of solid carbon is explained by the exponential temperature dependence of the number of electrons emitted by it. This dependence takes place when the plasma flows around the surfaces of both reagents. The formation of carbide shells on the reagent surfaces is caused by the secondary interaction of carbon with a reduced metal on the oxide surface or of oxide lattice fragments with carbon on the corrosion resistance surface. The formation of carbide shells “poisons” the reagent surface and retards and stops reduction. This process renews after breaking the shells upon melting and flowing carbides. The detected laws manifest themselves during both direct and indirect reduction, make the concepts of both mechanisms closer, and eliminate the theoretical discrepancies observed between them in practice.

Antimicrobial activity of selective transition metal co-ordination complexes of myristic acid

A series of co-ordination complexes of Mn(II), Cu(II) and Zn(II) with myristic acid have been synthesized by simple precipitation method. The shift in the absorption peaks of these selective transition metal complexes were well characterized by UV–Visible spectroscopy. Elemental and EDX analysis of these complexes were consistent with the proposed formula. FT-IR spectrum confirmed the transition metal linkage with myristic acid. Thermogravimetric studies of these co-ordination complexes depicted its thermal stability and molecular structure arrangement. Further, these transition metal complexes and its ligand have been screened for their antibacterial and antifungal activity. The cell viability of the solid complexes was also studied from MTT assay.

Inclusion complex vs. conjugation of hydrophobic photosensitizers with β-cyclodextrin: Improved disaggregation and photodynamic therapy efficacy against glioblastoma cells.

Self-aggregation of hydrophobic porphyrin-based photosensitizers (PSs) in aqueous biological environment decreases their bioavailability and in vivo therapeutic efficacy, which hampers their clinical use in photodynamic therapy (PDT). In the current study, we explore three new supramolecular systems based of hydrophobic PSs (i.e. 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (mTHPP) or 5-(4-carboxyphenyl)-10,15,20-triphenylporphyrin (P1COOH)) non-covalently or covalently attached to β-CD. The two non-covalent solid inclusion complexes (β-CD)2/mTHPP and [(β-CD)/P1COOH]4 are prepared by a new co-precipitation@lyophilization combined method and the covalent conjugate β-CD-P1 by click chemistry. The binding type effect and effectiveness on the disaggregation in aqueous medium and in vitro PDT efficacy against glioblastoma cancer cells of PSs are investigated for the three β-CD/PS systems. The findings reveal a remarkable improvement of the disaggregation and in vitro PDT activity of these β-CD/PS systems compared to the free PSs, except for [(β-CD)/P1COOH]4 inclusion complex caused by J-type self-aggregation of the inclusion complex in tetrameric form. β-CD-P1 conjugate shows the higher in vitro PDT efficacy compared to the other β-CD/PS systems. Overall, the results indicate that the disaggregation in aqueous medium and in vitro PDT activity of hydrophobic PSs can be improved by their binding to β-CD and the covalent binding is the best approach.

Aqueous solubility of kinase inhibitors: II the effect of hexadimethrine bromide on the dovitinib/γ-cyclodextrin complexation

Dovitinib is a small molecule kinase inhibitor (KI) that is practically insoluble in water but demonstrates high antitumor activity. The aqueous solubility of dovitinib can be improved through formation of water-soluble γ-cyclodextrin (γCD) complexes. However, the very low intrinsic solubility hammers the complex formation. The aim of the present study was to investigate dovitinib binary and ternary complexes with both γCD and hexadimethrine bromide (HDMBr) in both aqueous solution and the solid state. The phase-solubility diagrams of dovitinib were of Bs-type. Addition of HDMBr to the complexation media, that is formation of ternary dovitinib/γCD/HDMBr complex, resulted in four-fold increase in the complexation efficacy (CE). The enhanced CE can decrease the amount of γCD needed to solubilize given amount of dovitinib. The solid dovitinib complexes were characterized by differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR), and in vitro dissolution. The dissolution test showed that γCD did stabilize supersaturated dovitinib solution.

Utilization of tannic acid into spherical structured carbons based on charge-transfer complexation with tetracyanoethylene acceptor: Liquid-liquid and solid-solid interactions

In this study, liquid-liquid and solid-solid interactions between tannic acid (TA) as a donor with tetracyanoethylene (TCNE) acceptor were investigated toward understanding the effect of starting material phase on the end product of a charge transfer (CT) reaction. The liquid-liquid interaction generated a reddish-brown, soluble CT complex, while the solid-solid interaction produced a deep-violet, solid CT complex. The stoichiometry of the interaction was obtained using an elemental analysis of the solid product and spectrophotometric titration and Job's method for the soluble product and these data both indicated a 1:5 (TA:TCNE) molar ratio. The UV–visible and IR measurements support the presence of π-π interactions between the TA donor and TCNE acceptor. The two CT complexes obtained from the two interactions were directly carbonized into particles. These resultant carbon particles were fully characterized using IR, XRD, SEM, and TEM. These analyses revealed that carbon particles with spherical morphology were obtained after the carbonization of the CT complex generated through the solid-solid interaction, while the liquid-liquid interaction led to carbon particles with semi-porous, irregular morphology.

Synthesis, Characterization, and Biological Evaluation of a New Hydrogen-Bonded Charge-Transfer Complex of 2-Amino-4-methoxy-6-methylpyrimidine

A new hydrogen-bonded charge-transfer (HB-CT) complex formed between the donor 2-amino-4-methoxy-6-methylpyrimidine (AMMP) and theπ-acceptor 2,5-dihydroxy-p-benzoquinone (DHBQ) was investigated in both solid and solution states. The investigation was conducted using UV-Vis, CHN, FTIR,1H NMR, XRD, and TG-DTA analyses. The molecular composition of the CT complex in MeOH was found to be 1 : 1. The formation constant (KCT), molecular extinction coefficient (ε), and several other spectroscopic physical parameters were evaluated at different temperatures. The thermodynamic properties of the CT interaction in MeOH were studied by calculating the enthalpy (ΔH°), entropy (ΔS°), and free energy (ΔG°). The thermodynamic parameters indicated that van der Waals interactions and hydrogen bonding occur between AMMP and DHBQ in MeOH. The CHN, FTIR, and TG-DTA measurements confirmed that the solid HB-CT complex forms in a 2 : 1 ratio, i.e., [(AMMP)2(DHBQ)], and exhibits high stability. Moreover, XRD analysis was used to establish that the mean particle size of the complex is 23 nm. Finally, the solid HB-CT complex was screened for its antibacterial, antifungal, and antioxidant activities. It shows good activity against various bacterial and fungal species. Furthermore, the HB-CT complex exhibits good DPPH scavenging activity.

Self-Assembly of Bispentadecylphenol Substituted Perylenediimide with PS-b-P4VP for Structure–Property Insight into the Core of Core–Shell Micelles

We report the use of a ditopic molecular probe bispentadecylphenol substituted perylenediimide (PBI–PDP) to examine the molecular level self-assembly of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) in tetrahydrofuran (THF). A series of complexes were prepared between PS-b-P4VP copolymers with varying lengths of the 4-vinylpyridine chain and PBI–PDP. Light scattering and NMR spectroscopic studies reveal that the self-assembled structures of the solid complexes are not fully disrupted when the complexes are dissolved in THF. NMR experimental parameters measured for the small probe molecule provide detailed insights into the structure of the assemblies in solution as well as the interaction between the small molecule and the block copolymer. Such insights can have important implications in manipulating the nanostructure of block copolymer micelles to suit various application requirements. The dynamics and distribution of the PBI–PDP molecules within the assemblies in solution show a dependence on the leng...