Intramolecular charge transfer reaction, polarity, and dielectric relaxation in AOT/water/heptane reverse micelles: pool size dependence

Intramolecular charge transfer (ICT) reaction in a newly synthesized molecule, of 4-(1-morpholenyl) benzonitrile (M6C), in AOT/water/heptane reverse micelles at different pool sizes has been studied by using steady-state and time-resolved fluorescence emission spectroscopy. The pool size dependences of the reaction equilibrium constant and reaction rate have been explained in terms of the average polarity of the confined solvent pools estimated from the fluorescence emission Stokes shift of a nonreactive probe, coumarin 153, dissolved in these microemulsions. The complex permittivity measurements in the frequency range 0.01相似文献   

Photophysics and locations of IR125 and C152 in AOT reverse micelles

Many fluorescent chromophores have been employed to investigate the nature and dynamics of the water confined in reverse micelles (RMs). However, some questions remain as to the location of a probe in a RM and the diameter of the RM at which the physical characteristic of the water inside RMs becomes similar to that of bulk water. In this work, we systematically studied the photophysics of IR125 and C152 in AOT RMs at different w(0) by means of static absorption and fluorescence spectroscopy as well as time-resolved fluorescence spectroscopy. We obtained the absorption maxima, fluorescence emission maxima, fluorescence lifetime, and reorientation time of IR125 and C152 in AOT RMs at corresponding w(0). We found that all obtained photophysical parameters of IR125 and C152 in AOT RMs as a function of w(0) have a distinct changeover point around w(0) = 8, indicating that there is a dramatic change in the nature of the water confined in AOT RMs around w(0) = 8. The observed changeover point around w(0) = 8 is well in agreement with the Satpati's report (ChemPhysChem, 2009, 10, 2966). In addition, we observed that the measured reorientation time of IR125 in AOT RMs increases with the increase of w(0), which is opposite to the trend of change in the measured reorientation time of C152 in AOT RMs with the increase of w(0). We found that IR125 prefers to reside in the water pool of AOT RMs and that C152 prefers to reside in the outer side of the interfacial region or the nonpolar n-heptane phase of AOT RMs. Furthermore, we found that the time-resolved fluorescence anisotropy of IR125 in smaller w(0) AOT RMs primarily measures the reorientation of RMs and the time-resolved fluorescence anisotropy of IR125 in larger w(0) AOT RMs measures the reorientation of IR125 in the water pool confined in RMs. This work demonstrated that IR125 is an excellent probe to study the nature and dynamics of the water confined in AOT RMs.     

Correlating proton transfer dynamics to probe location in confined environments

The dramatic impact of differing environments on proton transfer dynamics of the photoacid HPTS prompted us to investigate these systems with two highly complementary methods: ultrafast time-resolved transient absorption and two-dimensional NMR spectroscopies. Both ultrafast time-resolved transient absorption spectroscopy and time-resolved anisotropy decays demonstrate the proton transfer dynamics depend intimately on the specific reverse micellar system. For w(0) = 10 reverse micelles formed with anionic AOT surfactant, the HPTS proton transfer dynamics are similar to dynamics in bulk aqueous solution, and the corresponding (1)H 2D NOESY NMR spectra display no cross peaks between HPTS and AOT consistent with the HPTS residing well hydrated by water in the interior of the reverse micelle water pool. In contrast, ultrafast transient absorption experiments show no evidence for HPTS photoinduced proton transfer reaction in reverse micelles formed with the cationic CTAB surfactant. In CTAB reverse micelles, clear cross peaks between HPTS and CTAB in the 2D NMR spectra show that HPTS embeds in the interface. These results indicate that the environment strongly impacts the proton transfer reaction and that complementary experimental techniques develop understanding of how location critically affects molecular responses.     

Vibrational relaxation pathways of AI and AII modes in N-methylacetamide clusters

We studied the pathways of vibrational energy relaxation of the amide I (~1660 cm?1) and amide II (~1560 cm?1) vibrational modes of N-methylacetamide (NMA) in CCl? solution using two-color femtosecond vibrational spectroscopy. We measured the transient spectral dynamics upon excitation of each of these amide modes. The results show that there is no energy transfer between the amide I (AI) and amide II (AII) modes. Instead we find that the vibrational energy is transferred on a picosecond time scale to a common combination tone of lower-frequency modes. By use of polarization-resolved femtosecond pump-probe measurements we also study the reorientation dynamics of the NMA molecules and the relative angle between the transition dipole moments of the AI and AII vibrations. The spectral dynamics at later times after the excitation (>40 ps) reveal the presence of a dissociation process of the NMA aggregates, trimers, and higher order structures into dimers and monomers. By measuring the dissociation kinetics at different temperatures, we determined the activation energy of this dissociation E(a) = 35 ± 3 kJ mol?1.     

Dynamics of solvent and rotational relaxation of glycerol in the nanocavity of reverse micelles

The dynamics of solvent and rotational relaxation of Coumarin 480 and Coumarin 490 in glycerol containing bis-2-ethyl hexyl sulfosuccinate sodium salt (AOT) reverse micelles have been investigated with steady-state and time-resolved fluorescence spectroscopy. We observed slower solvent relaxation of glycerol confined in the nanocavity of AOT reverse micelles compared to that in pure glycerol. However, the slowing down in the solvation time on going from neat glycerol to glycerol confined reverse micelles is not comparable to that on going from pure water or acetonitrile to water or acetonitrile confined AOT reverse micellar aggregates. While solvent relaxation times were found to decrease with increasing glycerol content in the reverse micellar pool, rotational relaxation times were found to increase with increase in glycerol content.     

Excited-state proton transfer of 2-(2'-pyridyl)benzimidazole in microemulsions: selective enhancement and slow dynamics in aerosol OT reverse micelles with an aqueous core

Excited-state proton transfer (ESPT) of 2-(2'-pyridyl)benzimidazole (2PBI) in reverse micelles has been studied by steady-state and time-resolved fluorescence spectroscopy. The nanometer sized water pool in the n-heptane/Aerosol OT (AOT)/water microemulsion is found to promote tautomer emission of this probe, as is evident from the emergence of a Stokes shifted band at 450 nm at the expense of the normal emission band on increasing the water content of the system. In the nonaquous microemulsion with a methanol core, the normal emission is quenched but no tautomer emission is obtained. With an acetonitrile core, there is no change in emission properties. Similarly, there is no evidence of ESPT in Triton X-100 reverse micelles. This indicates the requirement of ESPT to occur in microheterogeneous media; the medium should be a ternary system comprised of water and a hydrophobic phase separated by a negatively charged interface. In the microemulsions with an aqueous core, the fluorescence decays of 2PBI at the red end exhibit rise times of 0.8 ns and the time-resolved area-normalized emission spectra (TRANES) exhibit an isoemissive point, indicating slow dynamics of the two-state ESPT of 2PBI in aqueous AOT reverse micelles. The origin of the selective enhancement in AOT microemulsions as well as the slow dynamics is explored using fluorescence spectroscopic techniques, with support from quantum chemical calculation.     

Validation and divergence of the activation energy barrier crossing transition at the AOT/lecithin reverse micellar interface

In this report, the validity and divergence of the activation energy barrier crossing model for the bound to free type water transition at the interface of the AOT/lecithin mixed reverse micelle (RM) has been investigated for the first time in a wide range of temperatures by time-resolved solvation of fluorophores. Here, picosecond-resolved solvation dynamics of two fluorescent probes, ANS (1-anilino-8-naphthalenesulfonic acid, ammonium salt) and Coumarin 500 (C-500), in the mixed RM have been carefully examined at 293, 313, 328, and 343 K. Using the dynamic light scattering (DLS) technique, the size of the mixed RMs at different temperatures was found to have an insignificant change. The solvation process at the reverse micellar interface has been found to be the activation energy barrier crossing type, in which interface-bound type water molecules get converted into free type water molecules. The activation energies, Ea, calculated for ANS and C-500 are 7.4 and 3.9 kcal mol(-1), respectively, which are in good agreement with that obtained by molecular dynamics simulation studies. However, deviation from the regular Arrhenius type behavior was observed for ANS around 343 K, which has been attributed to the spatial heterogeneity of the probe environments. Time-resolved fluorescence anisotropy decay of the probes has indicated the existence of the dyes in a range of locations in RM. With the increase in temperature, the overall anisotropy decay becomes faster revealing the lability of the microenvironment at elevated temperatures.     

Excited-state double proton transfer of 7-azaindole in water nanopools

The excited-state proton-transfer dynamics of 7-azaindole occurring in the water nanopools of reverse micelles has been investigated by measuring time-resolved fluorescence spectra and kinetics, as well as static absorption and emission spectra, with varying water content and isotope. 7-Azaindole molecules are found to exist in the bound-water regions of reverse micelles. The rate constant and the kinetic isotope effect of proton transfer are smaller than those in bulk water although both increase with the size of the water nanopool. The retardation of proton transfer in the bound regions is attributed to the increased free energy of prerequisite solvation to form a cyclically H-bonded 1:1 7-azaindole/water complex.     

Local environment and property of water inside the hollow cylinder of a lipid nanotube

We investigated the local environment of water confined inside the hollow cylinder of lipid nanotubes (LNTs) by time-resolved fluorescent measurements and attenuated-total-reflectance infrared (ATR-IR) spectroscopy. The LNT was obtained by self-assembly of cardanyl glucosides in water at room temperature and had an open-ended cylindrical nanospace with a diameter of 10-15 nm, a length of 10-100 microm, and hydrophilic inner and outer surfaces. We introduced a fluorescent probe of 8-anilinonaphthalene-1-sulfonate into the confined water and observed an extremely slow dynamic Stokes shift with a correlation time of 1.26 ns, which was 2-3 orders of magnitude longer than that of bulk-phase water. From the peak shift of the fluorescent spectrum, the local solvent polarity (ET(30)) of the confined water was estimated as 50 kcal/mol, which is 20% lower than that in bulk water. ATR-IR measurements showed that the hydrogen-bond network of water inside the LNT was more developed than that in bulk water at room temperature, which is in contrast to the water in other self-assembled confined geometries, such as Aerosol-OT (AOT) reversed micelles.     

An Experimental Study on the Relationship between the Physical Properties of CTAB/Hexanol/Water Reverse Micelles and ZrO2-Y2O3 Nanoparticles Prepared

Based on the studies of their physical properties such as aqueous solution uptake, electric conductivity, and microstructure, CTAB/hexanol/water reverse micelles (CTAB, cetyltrimethyl ammonium bromide) were used to prepare ZrO2-Y2O3 nanoparticles. The relationship between the micelle microstructure and size, morphology, and aggregate properties of particles prepared was also investigated. It has been found that with high CTAB concentration ([CTAB] > 0.8 mol/l), the reverse micelles can solubilize a sufficient amount of aqueous solution with high metallic ion concentration ( approximately 1.0 mol/L), while the microstructure of the reverse micelles keeps unchanged. The most important factor affecting the size and shape of reverse micelles was found to be the water content w0 (w0, molar ratio of water to surfactant used). When both the CTAB concentration and the w0 values are low, the diameters of reverse micelles are below 20 nm, and the ZrO2-Y2O3 particles prepared are also very small. However, the powders obtained were found to form a lot of aggregates after drying and calcination. High CTAB concentration, high w0 value, and high metallic ion concentration in the aqueous phase for high powder productivity were found to be the suitable compositions of reverse micelles for preparing high-quality ZrO2-Y2O3 nanoparticles. Under these conditions, the reverse micelles are still spherical in shape even the reverse micellar system is nearly saturated with aqueous solutions. These reverse micelles were found to have a diameter of between 60 and 150 nm and the ZrO2-Y2O3 particles prepared therefrom range from 30 to 70 nm with spherical shape and not easy to form aggregates. Copyright 1999 Academic Press.     

2,4-二硝基氯苯碱性水解胶团催化的活化能

研究了阳离子表面活性剂氯化十六烷基吡啶(CPC)和十六烷基三甲基氯化铵(CTAC)胶团对2,4-二硝基氯苯(DNCB)碱性水解的催化作用和小分子极性有机物丁醇的加入对该反应的影响,计算了反应活化能.结果表明:(1)CPC和CTAC胶团对DNCB碱性水解都有明显的催化作用;(2)加入少量叔丁醇略有利于提高催化效果;(3)在CPC和CTAC胶团溶液中DNCB碱性水解反应的活化能约为49kJ/mol,比纯水中的91kJ/mol低得多,说明反应机制可能存在差异.     

An example of how to use AOT reverse micelle interfaces to control a photoinduced intramolecular charge-transfer process

6-Propionyl-2-(N,N-dimethyl)aminonaphtahalene, PRODAN, is widely used as a fluorescent molecular probe due to its significant Stokes shift in polar solvents. It is an aromatic compound with intramolecular charge-transfer (ICT) states which can be particularly useful as sensors. In this work, we performed absorption, steady-state, time-resolved fluorescence (TRES), and time-resolved area normalized emission (TRANES) spectroscopies on PRODAN dissolved in nonaqueous reverse micelles. The reverse micelles are composed of polar solvents/sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT)/n-heptane. Sequestered polar solvents included ethylene glycol (EG), propylene glycol (PG), glycerol (GY), formamide (FA), dimethylformamide (DMF), and dimethylacetamide (DMA). The experiments were performed with varying surfactant concentrations at a fixed molar ratio W(S) = [polar solvent]/[AOT]. In every reverse micelle studied, the results show that PRODAN undergoes a partition process between the external solvent and the reverse micelle interface. The partition constants, K(p), are quantified from the changes in the PRODAN emission and/or absorption spectra with the surfactant concentration. The K(p) values depend strongly on the encapsulated polar solvent and correlate quite well with the AOT reverse micelle interface's zones where PRODAN can exist and emits. Thus, the partition toward the reverse micelle interface is strongly favored in DMF and DMA containing micelles where the PRODAN emission comes only from an ICT state. For GY/AOT reverse micelles, the K(p) value is the lowest and only emission from the local excited (LE) state is observed. On the other hand, for EG/AOT, PG/AOT, and water/AOT reverse micelles, the K(p) values are practically the same and emission from both states (LE and ICT) is simultaneously detected. We show here that it is possible to control the PRODAN state emission by simply changing the properties of the AOT reverse micelle interfaces by choosing the appropriate polar solvent to make the reverse micelle media. Indeed, we present experimental evidence with the answer to the long time question about from which state does PRODAN emit, a process that can be controlled using the unique reverse micelle interfaces properties.     

SOMATOSTATIN IN A WATER-RESTRICTED ENVIRONMENT: FLUORESCENCE AND CIRCULAR DICHROISM STUDY IN AOT REVERSE MICELLES

Abstract— Steady-state and time-resolved fluorescence emission from the single tryptophan residue of somatostatin, and the kinetics of quenching of this emission, were studied in aqueous solution and in reverse micelles of sodium bis (2-ethylhexyl) sulfosuccinate (AOT)/water/isooctane, a system that mimics the water-membrane interface well- Incorporation into micelles caused blue shifts and reduced band-widths of the emission peaks and altered the quantum yields with respect to emission from bulk water. Steady-state anisotropy values also increased considerably on micellization. These observations point to reduced polarity of the environment around the Tip residue of the peptide, as well as restricted freedom of its rotational motions, due to transfer from the aqueous to the micellar phase. Fluorescence emission kinetics of the Tip moiety followed biexponential decay laws in both aqueous and micellar media. Static and dynamic quenching constants were measured for acrylamide and CC1₄ quenchers localized in the micellar and organic pseudophases, respectively, using both steady-state and time-resolved experiments. The efficiency of dynamic quenching by acrylamide became vanishingly small in going from water to reverse micelles, in sharp contrast to the comparable quenching efficiencies exhibited by CC1₄ in micelles and acrylamide in water. The circular dichroic (CD) spectrum of the native peptide in water indicated the possibility of some amount of P-type secondary structure being present. Conformational analysis of CD spectra in micelles showed that the relative amount of this structural feature was enhanced for the micellized peptide but was insensitive to the water content of micelles. The above results, put together, indicate that the Trp-8 residue in somatostatin is likely to be located in the close neighborhood of the water-AOT molecular interface, where the water molecules are strongly immobilized. This work also demonstrates the role of reverse micelles as a convenient membrane-mimetic medium for the study of membrane interactions of bioactive peptides.     

Aggregation Behaviors of Tricarbocyanine Dye in Water and in AOT Reverse Micelles

The photophysical property of the tricarbocyanine dye IR144 has been extensively studied in non‐aqueous solvents. However, as a potential near‐infrared biomedical imaging probe, the photophysical property of IR144 in water is still little known. So, the aggregation behaviors of IR144 in water with steady‐state absorption spectroscopy and integrated polarization dependent femtosecond pump‐probe spectroscopy were investigated. Through comparing the absorption spectral bandshape of IR144 in water and in water pool of AOT reverse micelles, It is found that IR144 form dimer aggregates in water even at very low concentration (<1.0×10^?7 mol·L^?1). And the absorption spectrum of the IR144 aggregates always displays a bimodal feature, which is independent of the dye concentration ranging from 1.0×10^?7 to 1.0×10^?4 mol·L^?1. For better understanding the aggregation behaviors of IR144 in water, we measured the ground state recovery kinetics and the reorientation kinetics of IR144 in water and in water pool of AOT reverse micelles (W₀=[H₂O]/[AOT], W₀=40). It is found that the fluorescence quantum yield of IR144 in water is lower than that in water pool of AOT reverse micelles, and the reorientation time of IR144 in water is slower than that in water pool of AOT reverse micelles. Those kinetic measurements also verify that IR144 exists as dimer aggregates in water.     

Temperature dependence of looping rates in a short peptide

Knowledge of the influence of chain length and amino acid sequence on the structural and dynamic properties of small peptides in solution provides essential information on protein folding pathways. The combination of time-resolved optical spectroscopy and molecular dynamics (MD) simulation methods has become a powerful tool to investigate the kinetics of end-to-end collisions (looping rates) in short peptides, which are relevant in early protein folding events. We applied the combination of both techniques to study temperature-dependent (280-340 K) looping rates of the Dbo-AlaGlyGln-Trp-NH2 peptide, where Dbo represents a 2,3-diazabicyclo[2.2.2]oct-2-ene-labeled asparagine, which served as a fluorescent probe in the time-resolved spectroscopic experiments. The experimental looping rates increased from 4.8 x 10(7) s(-1) at 283 K to 2.0 x 10(8) s(-1) at 338 K in H2O. The corresponding Arrhenius plot provided as activation parameters Ea = 21.5 +/- 1.0 kJ mol(-1) and ln(A/s-1) = 26.8 +/- 0.2 in H2O. The results in D2O were consistent with a slight solvent viscosity effect, i.e., the looping rates were 10-20% slower. MD simulations were performed with the GROMOS96 force field in a water solvent model, which required first a parametrization of the synthetic amino acid Dbo. After corrections for solvent viscosity effects, the calculated looping rates varied from 1.5 x 10(8) s(-1) at 280 K to 8.2 x 10(8) s(-1) at 340 K in H2O, which was about four times larger than the experimental data. The calculated activation parameters were Ea = 24.7 +/- 1.5 kJ mol(-1) and ln(A/s(-1)) = 29.4 +/- 0.1 in H2O.     

Water dynamics--the effects of ions and nanoconfinement

Hydrogen bond dynamics of water in highly concentrated NaBr salt solutions and reverse micelles are studied using ultrafast 2D-IR vibrational echo spectroscopy and polarization-selective IR pump-probe experiments performed on the OD hydroxyl stretch of dilute HOD in H(2)O. The vibrational echo experiments measure spectral diffusion, and the pump-probe experiments measure orientational relaxation. Both experimental observables are directly related to the structural dynamics of water's hydrogen bond network. The measurements performed on NaBr solutions as a function of concentration show that the hydrogen bond dynamics slow as the NaBr concentration increases. The most pronounced change is in the longest time scale dynamics which are related to the global rearrangement of the hydrogen bond structure. Complete hydrogen bond network randomization slows by a factor of approximately 3 in approximately 6 M NaBr solution compared to that in bulk water. The hydrogen bond dynamics of water in nanoscopically confined environments are studied by encapsulating water molecules in ionic head group (AOT) and nonionic head group (Igepal CO 520) reverse micelles. Water dynamics in the nanopools of AOT reverse micelles are studied as a function of size by observing orientational relaxation. Orientational relaxation dynamics deviate significantly from bulk water when the size of the reverse micelles is smaller than several nm and become nonexponential and slower as the size of the reverse micelles decreases. In the smallest reverse micelles, orientational relaxation (hydrogen bond structural randomization) is almost 20 times slower than that in bulk water. To determine if the changes in dynamics from bulk water are caused by the influence of the ionic head groups of AOT or the nanoconfinement, the water dynamics in 4 nm nanopools in AOT reverse micelles (ionic) and Igepal reverse micelles (nonionic) are compared. It is found that the water orientational relaxation in the 4 nm diameter nanopools of the two types of reverse micelles is almost identical, which indicates that confinement by an interface to form a nanoscopic water pool is a primary factor governing the dynamics of nanoscopic water rather than the presence of charged groups at the interface.     

Effect of pH on the fluorescence and absorption spectra of hypericin in reverse micelles

The well-characterized, monodispersed nature of reverse micelles formed by sodium bis(2-ethylhexyl)sulfosuccinate/heptane and their usefulness in approximating a membrane-like environment have been exploited to investigate the effect of pH and water pool size on the photophysical properties of hypericin (Hyp). Our measurements reveal two titratable groups of pKa approximately 1.5 and approximately 12.5. These are assigned to the HypH+/Hyp equilibrium (the deprotonation of a carbonyl group) and the Hyp-/Hyp2- equilibrium (the deprotonation of a peri hydroxyl group). The low-energy absorbance maxima of HypH+, of Hyp and Hyp- and of Hyp2- are 583, 594 and 613 nm, respectively. Neither at pH 13 nor at 1 M HCl is the system entirely in the Hyp2- or the HypH+ forms. Ours is the first study of Hyp in reverse micelles as well as the first time-resolved study of Hyp as a function of pH.     

设计p-n同质结构实现碳氮光催化剂的全解水性能

非金属氮化碳(CN)因其独特的光催化性能而备受关注.本文利用水热处理、高温烧结、高能球磨和烧结的方法成功制得一种具有混合结构的CN光催化剂.先以三聚氰胺为原料进行水热处理(180℃,24 h),过滤干燥后,转移到高纯氩气保护下的管式炉中,于550℃处理1 h得到CN材料.然后将CN用三聚氰胺和氟化铵水热180℃处理24 h,过滤、干燥、煅烧(550℃,1 h)得到第二种材料.最后将其与CN材料按等比例混合,经高能球磨研磨,再于管式炉中在气氛保护下淬火,得到最终催化剂样品.由于这种结构的界面作用,使CN光催化剂显示出了高的光催化活性.它的产氢效果可以高达17028.82μmol h^–1g^–1,在420 nm光照下,其光量子效率也达到11.2%.随后,采用纳秒级别的时间分辨萤光(PL)光谱测得其荧光寿命为9.9 ns.有助于电子与空穴参与反应更有趣的是,在不加牺牲剂时,该光催化剂具有高效的全解水效果,其产氢效率为270.95μmol h^–1g^–1,产氧效率为115.21μmol h^–1g^–1,有望实际用于全解水反应中.另外,通过紫外可见漫反射光谱,PL光谱和材料的比表面等测试来考察该CN光催化剂效果好的原因.发现该材料具有更高比表面积有更多活性点参与反应.同时,通过电化学测试获得了肖特基曲线和电流-电压曲线,发现该光催化剂里含有少量的pn结构,这种结构使材料在弱光下也会产生光生载流子,实际上它是起到光生载流子的激发作用,即在相同光照下,就会产生更多的光生载流子数量,从而进一步提高了其催化效果.因此,本工作对优化碳氮光催化剂的催化效果有很好的指导意义.     

Vibrational dynamics of ice in reverse micelles

The ultrafast vibrational dynamics of HDO:D(2)O ice at 180 K in anionic reverse micelles is studied by midinfrared femtosecond pump-probe spectroscopy. Solutions containing reverse micelles are cooled to low temperatures by a fast-freezing procedure. The heating dynamics of the micellar solutions is studied to characterize the micellar structure. Small reverse micelles with a water content up to approximately 150 water molecules contain an amorphous form of ice that shows remarkably different vibrational dynamics compared to bulk hexagonal ice. The micellar amorphous ice has a much longer vibrational lifetime than bulk hexagonal ice and micellar liquid water. The vibrational lifetime is observed to increase linearly from 0.7 to 4 ps with the resonance frequency ranging from 3100 to 3500 cm(-1). From the pump dependence of the vibrational relaxation the homogeneous linewidth of the amorphous ice is determined (55+/-5 cm(-1)).     

Charge-transfer guest interactions in luminescent MOFs: implications for solid-state temperature and environmental sensing

One of the ongoing goals in the field of porous materials is the design and synthesis of materials that possess chemical structures amenable for use in sensing applications. We describe the preparation, luminescence characteristics, and environmental sensing properties of variants of the aluminum-based MOF [Al(OH)(O(2)C-C(10)H(6)-CO(2))](∞). Careful activation of the open framework complex, 1, yielded a dynamic structural transformation to a non-porous form, 2, that exhibited strong inter-linker interactions and red-shifted emission characteristics indicative of dimer formation. We also demonstrate the formation of highly luminescent ground-state charge-transfer (CT) complexes between 1 and the electron-donating amines dimethylamine (DMA) (1a), and N,N-diethylaniline (DEA) (1b), both of which exhibit dual-emission characteristics and a ratiometric luminescence response that is sensitive to temperature and solvent polarity. Steady-state and time-resolved measurements on 1a, 1b, and 2 indicate that the MOF structures stabilize ground-state CT interactions that are distinct from the weakly-bound exciplexes formed in comparable mixtures of purely organic components. The spectra for 1a and 1b also indicate different temperature dependencies that correspond to thermally-activated complex formation (ΔH(f) = +1.1 ± 0.2 kcal mol(-1)) in 1a and static quenching effects (ΔH(f) = -2.2 ± 0.3 kcal mol(-1)) in 1b. The addition of ethanol, isopropanol, toluene, or chloroform to suspensions of 1b indicate destabilization of the CT state with increasing solvent polarity, which suggests the generalized application of this or related materials in sensor applications.