[Determination of multiple restricted and prohibited ingredients in hair dyes using a novel 3D stationary phase coupled with gas chromatography-mass spectrometry].

Hair dyes (HDs) are mainly composed of various benzene series, amines, and phenolic compounds. These ingredients are well known to have allergenic, teratogenic, and carcinogenic properties. As such, the presence of these ingredients in HDs has received increased attention in recent years. At present, the applications of traditional analytical and detection methods and commercial chromatographic columns are limited by problems such as poor qualitative analysis and inaccurate quantification. Thus, the development of new analytical and detection technologies and stationary phases is an urgent endeavor. Moreover, HDs contain complex compounds and exhibit significant matrix interference. Hence, appropriate sample pretreatment methods are necessary to analyze HDs. In this study, the 3D nonpolar rigid structure of triptycene (TP) was combined with the polar flexible chains of polyethylene glycol (PEG) to design and synthesize a TP derivative, TP-PEG, as a stationary phase for chromatographic columns. The stationary phase enabled the expansion of the selection range for polar and nonpolar analytes. Subsequently, gas chromatography-mass spectrometry (GC-MS) was used to quantitatively analyze 22 ingredients in HDs. The experimental results demonstrated that analytes with different polarities exhibited sharp and symmetrical peak shapes on the stationary phase, and all 22 analytes achieved baseline separation on the chromatographic column. The 22 ingredients in HDs showed good linear relationships within their respective ranges, with correlation coefficients greater than 0.9985. The average recovery rates at three spiked levels were in the range of 89.2%-103.2%, and RSDs were less than 5%. Compared with traditional methods, the proposed method has higher efficiency and better accuracy, thus verifying the excellent separation performance of the new stationary phase and the effectiveness of the established GC-MS detection method. The findings indicated the applicability of the developed method to the detection and analysis of various compounds in HDs.

Hydroxyl-Functionalized Polymers of Intrinsic Microporosity and Dual-Functionalized Blends for High-Performance Membrane-Based Gas Separations.

Membrane technology has shown significant growth during the past two decades in the gas separation industry due to its energy-savings, compact and modular design, continuous operation, and environmentally benign nature. Robust materials with higher permeability and selectivity are key to reduce capital and operational cost, pushing it forward to replace or debottleneck conventional energy-intensive unit operations such as distillation. Recently designed ladder polymers of intrinsic microporosity (PIM) and polyimides of intrinsic microporosity (PIM-PI) with pores <20 Å have demonstrated excellent gas permeation performance. Here, a series of plasticization-resistant PIM-based membrane materials is reported, including the first example of a hydroxyl-functionalized triptycene- and Tröger's base-derived ladder PIM and two PIM-PI homopolymers and a series of dual-functionalized polyimide blends containing hydroxyl- and carboxyl-functionalized groups. Specifically, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)-based PIM-PI blends demonstrated extremely high selectivity for a variety of industrially important applications. An optimized polyimide blend containing ─OH and ─COOH groups showed permselectivity values of 136 for CO2/CH4, 11.4 for O2/N2 and 636 for H2/CH4. Such extreme size-sieving capabilities are attributed to physical crosslinking induced by strong hydrogen bonding forming tightly structured polymer networks. The study provides a new general strategy for developing plasticization resistant, robust, and highly-selective PIM-based membrane materials.

Triptycene-Based Tripodal Molecular Platforms.

Molecular platforms are essential components of various surface-mounted molecular devices. Here, we document the synthesis of two universal triptycene-based tripodal pedestals featuring terminal alkynes in the axial position. We showcase their versatility by incorporating them into the structures of diverse functional molecules such as unidirectional light-driven molecular motors, photoswitches, and Brownian molecular rotors using standard cross-coupling reactions. We also present their fundamental physical properties, including acidity constants, data from differential scanning calorimetry, and crystallographic analysis of two parent and five derived structures. Finally, and importantly, we demonstrate that the photochemical properties of selected photoswitch representatives remain uncompromised when fused with tripods.

Covalently Linked 5,6,11,12-Tetraazanaphthacene Dimer and Its Triptycene-Capped Derivatives as Electron Acceptors.

The development of electron transport and n-type materials is still largely dominated by a limited number of organic semiconductors, with fullerenes at the forefront. In contrast, substantial progress has been made in developing hole transport and p-type materials. Therefore, expanding the range of electron acceptors, making them solution-processable, and elucidating their structural arrangement by X-ray crystallography is essential. We synthesised 2,2'-bi-(5,6,11,12-tetraazanaphthacene) (bi-TANC) and its triptycene end-capped derivative, 2,2'-bi(8,13-dihydro-8,13-[1,2]benzenonaphtho-5,6,15,16-tetraazanaphthacene) (bi-TpTANC), as electron acceptors. Bi-TANC exhibits a herringbone-like crystal packing with intermolecular π-π overlap, which is observed in typical organic n-type semiconductors. However, it showed poor solubility, similar to larger acenes. In contrast, bi-TpTANC exhibited favourable solubility, and its electrochemistry in solution was investigated. In the cyclic voltammogram of bi-TpTANC, reversible redox waves corresponding to 3-step/4-electron transfer were observed at -0.795 V (1e-), -0.927 V (1e-), and -1.44 V (2e-) as half-wave potentials. The redox wave associated with the two-electron transfer on the negative low-potential side indicates the presence of through-bond charge delocalisation in the monoanionic state. Furthermore, the LUMO level of bi-TpTANC is -4.1 eV, which indicates its potential as a promising air-stable n-type material.

Ultrafast Removal of Thorium and Uranium from Radioactive Waste and Groundwater Using Highly Efficient and Radiation-Resistant Functionalized Triptycene-Based Porous Organic Polymers.

Thorium (Th) and uranium (U) are important strategic resources in nuclear energy-based heavy industries such as energy and defense sectors that also generate significant radioactive waste in the process. The management of nuclear waste is therefore of paramount importance. Contamination of groundwater/surface water by Th/U is increasing at an alarming rate in certain geographical locations. This necessitates the development of strategic adsorbent materials with improved performance for capturing Th/U species from radioactive waste and groundwater. This report describes the design of a unique, robust, and radiation-resistant porous organic polymer (POP: TP-POP-SO3NH4), which demonstrates ultrafast removal of Th(IV) (<30 s)/U(VI) (<60 s) species present in simulated radioactive wastewater/groundwater samples. Thermal, chemical, and radiation stabilities of these POPs were studied in detail. The synthesized ammoniated POP revealed exceptional capture efficiency for trace-level Th (<4 ppb) and U (<3 ppb) metal ions through the cation-exchange mechanism. TP-POP-SO3NH4 shows a significant sorption capacity [Th (787 mg/g) and U (854 mg/g)] with an exceptionally high distribution coefficient (Kd) of 107 mL/g for Th. This work also demonstrates a facile protocol to convert a nonperforming POP, by simple chemical modifications, into a superfast adsorbent for efficient uptake/removal of U/Th.

Structure-Property Relationships for Potential Inversion From Electron Acceptors Based on Thiophene-Fused Triptycene Quinones, 1,4-Diketones and Their Malononitrile Adducts.

The synthesis and properties of a series of 11,11,12,12-tetracyano-9,10-anthraquinodimethane (TCAQ) inspired electron acceptors based on thiophene-fused quinone and triptycene motifs is presented. This has yielded insights into structure-property relationships for establishing and modulating simultaneous two-electron reduction processes in TCAQ analogues. These new compounds were synthesised using a Friedel-Crafts acylation between triptycene and thiophene-3,4-dicarbonyl chloride. Isomeric para-quinones featuring a [c]-fused thiophene on one side and a ß,ß- or α,ß-fused triptycene on the other were isolated alongside a thiophene-3,4-diketone which bears two triptycene fragments. Knoevenagel condensation of these products with malononitrile produced a quinoidal bis(dicyanomethylene), an oxo-dicyanomethylene and an acyclic bis(dicyanomethylene). This series of new electron accepting molecules has been studied using X-ray crystallography and the implications of their 3D structures on NMR and UV/vis absorbance spectroscopy and cyclic voltammetry results have been ascertained with conclusions underpinned by computational methods.

Rigidity with Flexibility: Porous Triptycene Networks for Enhancing Methane Storage.

In the pursuit of advancing materials for methane storage, a critical consideration arises given the prominence of natural gas (NG) as a clean transportation fuel, which holds substantial potential for alleviating the strain on both energy resources and the environment in the forthcoming decade. In this context, a novel approach is undertaken, employing the rigid triptycene as a foundational building block. This strategy is coupled with the incorporation of dichloromethane and 1,3-dichloropropane, serving as rigid and flexible linkers, respectively. This combination not only enables cost-effective fabrication but also expedites the creation of two distinct triptycene-based hypercrosslinked polymers (HCPs), identified as PTN-70 and PTN-71. Surprisingly, despite PTN-71 manifesting an inferior Brunauer-Emmett-Teller (BET) surface area when compared to the rigidly linked PTN-70, it showcases remarkably enhanced methane adsorption capabilities, particularly under high-pressure conditions. At a temperature of 275 K and a pressure of 95 bars, PTN-71 demonstrates an impressive methane adsorption capacity of 329 cm3 g-1. This exceptional performance is attributed to the unique flexible network structure of PTN-71, which exhibits a pronounced swelling response when subjected to elevated pressure conditions, thus elucidating its superior methane adsorption characteristics. The development of these advanced materials not only signifies a significant stride in the realm of methane storage but also underscores the importance of tailoring the structural attributes of hypercrosslinked polymers for optimized gas adsorption performance.

Highly Luminescent Chiral Carbon Nanohoops via Symmetry Breaking with a Triptycene Unit: Bright Circularly Polarized Luminescence and Size-Dependent Properties.

Chiral carbon nanohoops with both high fluorescence quantum yield and large luminescence dissymmetry factor are essential to the development of circularly polarized luminescence (CPL) materials. Herein, the rational design and synthesis of a series of highly fluorescent chiral carbon nanohoops TP-[8-13]CPPs via symmetry breaking with a chiral triptycene motif is reported. Theoretical calculations revealed that breaking the symmetry of nanohoops causes a unique size-dependent localization in the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular obtitals (LUMOs) as the increasing of sizes, which is sharply different from those of [n]cycloparaphenylenes. Photophysical investigations demonstrated that TP-[n]CPPs display size-dependent emissions with high fluorescence quantum yields up to 92.9% for TP-[13]CPP, which is the highest value among the reported chiral conjugated carbon nanohoops. The high fluorescence quantum yields are presumably attributed to both the unique acyclic, and radial conjugations and high radiative transition rates, which are further supported by theoretical investigations. Chiroptical studies revealed that chiral TP-[n]CPPs exhibit bright CPL with CPL brightness up to 100.5 M-1 cm-1 for TP-[11]CPP due to the high fluorescence quantum yield. Importantly, the investigations revealed the intrigued size-dependent properties of TP-[n]CPPs with regards to (chir)optical properties, which follow a nice linear relationship versus 1/n. Such a nice linear relationship is not observed in other reported conjugated nanohoops including CPPs.

Triptycene Branched Poly(aryl-co-aryl piperidinium) Electrolytes for Alkaline Anion Exchange Membrane Fuel Cells and Water Electrolyzers.

Alkaline polymer electrolytes (APEs) are essential materials for alkaline energy conversion devices such as anion exchange membrane fuel cells (AEMFCs) and water electrolyzers (AEMWEs). Here, we report a series of branched poly(aryl-co-aryl piperidinium) with different branching agents (triptycene: highly-rigid, three-dimensional structure; triphenylbenzene: planar, two-dimensional structure) for high-performance APEs. Among them, triptycene branched APEs showed excellent hydroxide conductivity (193.5 mS cm-1 @80 °C), alkaline stability, mechanical properties, and dimensional stability due to the formation of branched network structures, and increased free volume. AEMFCs based on triptycene-branched APEs reached promising peak power densities of 2.503 and 1.705 W cm-2 at 75/100 % and 30/30 % (anode/cathode) relative humidity, respectively. In addition, the fuel cells can run stably at a current density of 0.6 A cm-2 for 500 h with a low voltage decay rate of 46 µV h-1 . Importantly, the related AEMWE achieved unprecedented current densities of 16 A cm-2 and 14.17 A cm-2 (@2 V, 80 °C, 1 M NaOH) using precious and non-precious metal catalysts, respectively. Moreover, the AEMWE can be stably operated under 1.5 A cm-2 at 60 °C for 2000 h. The excellent results suggest that the triptycene-branched APEs are promising candidates for future AEMFC and AEMWE applications.

Palladium(II)-immobilized Triptycene based Hypercrosslinked Polymers: An Efficient, Green, and Reusable Heterogenous Catalyst for Suzuki-Miyaura Cross-coupling Reaction.

The Suzuki-Miyaura cross-coupling (SMCC) involves the coupling of organohalides and organoboron molecules in the presence of Pd(II)-based catalysts. Often SMCC reactions employ homogenous catalysts. However, such homogenous SMCC reactions are associated with certain limitations which has motivated design of effective and sustainable Pd(II)-based heterogeneous catalytic systems. Herein, we report a systematic development of a Pd(II)-immobilized and triptycene based ionic hyper crosslinked polymer (Pd@TP-iHCP) and explored its application as a heterogeneous catalyst for SMCC reaction. Pd@TP-iHCP has ample N-heterocyclic carbene (NHC) pendants that anchor Pd(II) centres on the polymeric matrix. Pd@TP-iHCP was characterized satisfactorily using FT-IR, 13 C CP-MAS NMR, BET surface area analysis, SEM, EDX and HRTEM. The performance of Pd@TP-iHCP as a heterogeneous catalyst for SMCC reactions was explored using various combinations of aryl boronic acids and aryl halides. Experimental results show that Pd@TP-iHCP is associated with a moderately high surface area. It is an efficient catalyst for SMCC (in aqueous media) with a modest loading of 0.8 mol % Pd(II)-catalyst since high yields of the expected products were obtained in shorter time intervals. Pd@TP-iHCP also features excellent stability and catalyst recyclability since it could be re-used for several cycles without any significant decrease in catalytic efficiency.

A Molecular Dynamics Study of Single-Gas and Mixed-Gas N2 and CH4 Transport in Triptycene-Based Polyimide Membranes.

Fluorinated polyimides incorporated with triptycene units have gained growing attention over the last decade since they present potentially interesting selectivities and a higher free volume with respect to their triptycene-free counterparts. This work examines the transport of single-gas and mixed-gas N2 and CH4 in the triptycene-based 6FDA-BAPT homopolyimide and in a block 15,000 g mol-1/15,000 g mol-1 6FDA-mPDA/BAPT copolyimide by using molecular dynamics (MD) simulations. The void-space analyses reveal that, while the free volume consists of small-to-medium holes in the 6FDA-BAPT homopolyimide, there are more medium-to-large holes in the 6FDA-mPDA/BAPT copolyimide. The single-gas sorption isotherms for N2 and CH4 over the 0-70 bar range at 338.5 K show that both gases are more soluble in the block copolyimide, with a higher affinity for methane. CH4 favours sites with the most favourable energetic interactions, while N2 probes more sites in the matrices. The volume swellings remain limited since neither N2 nor CH4 plasticise penetrants. The transport of a binary-gas 2:1 CH4/N2 mixture is also examined in both polyimides under operating conditions similar to those used in current natural gas processing, i.e., at 65.5 bar and 338.5 K. In the mixed-gas simulations, the solubility selectivities in favour of CH4 are enhanced similarly in both matrices. Although diffusion is higher in 6FDA-BAPT/6FDA-mPDA, the diffusion selectivities are also close. Both triptycene-based polyimides under study favour, to a similar extent, the transport of methane over that of nitrogen under the conditions studied.

Zn-Based Metal-Organic Frameworks Using Triptycene Hexacarboxylate Ligands: Synthesis, Structure, and Gas-Sorption Properties.

A series of metal-organic frameworks (MOFs) based on zinc ions and two triptycene ligands of different size have been synthesized under solvothermal conditions. Structural analyses revealed that they are isostructural 3D-network MOFs. The high porosity and thermal stability of these MOFs can be attributed to the highly rigid triptycene-based ligands. Their BET specific surface areas depend on the size of the triptycene ligands. In contrast to these surface-area data, the H2 and CO2 adsorption of these MOFs is larger for MOFs with small pores. Consequently, we introduced functional groups to the bridge-head position of the triptycene ligands and investigated their effect on the gas-sorption properties. The results unveiled the role of the functional groups in the specific CO2 binding via an induced interaction between adsorbates and the functional groups. Excellent H2 and CO2 properties in these MOFs were achieved in the absence of open metal sites.

Ultra-stable fully-aromatic microporous polyamide membrane for molecular sieving of nitrogen over volatile organic compound.

Microporous polymer membranes are promising candidates for industrial membrane-based gas separation because of their high separation performance. However, their relatively low stability due to the local rearrangement of polymer chains during usage remains a problem. Hence, we propose the construction of a fully aromatic polymer structure in a microporous polymer membrane to enhance membrane stability. Four triptycene-based microporous polyamides were synthesized via the polymerization of 2,6,14-triaminotriptycene with aromatic acyl chloride and/or aliphatic acyl chlorides. Their properties were characterized and compared by using nuclear magnetic resonance (NMR) and Brunauer-Emmett-Teller analyses. The synthesized polyamides were fabricated into composite membranes by employing a solution process; their stability was evaluated for the molecular sieving of nitrogen over volatile organic compounds such as cyclohexane. Low-field NMR and X-ray photoelectron spectroscopy were used to investigate the differences in the properties of membranes with different structures at different times. The results showed that the fully aromatic polyamide membrane made from 2,6,14-triaminotriptycene and aromatic acyl chloride displayed constant rejection (99 %) and nitrogen permeability (approximately 50 Barrer) for the molecular sieving of nitrogen over cyclohexane during 100-d experiments, indicating good stability. This approach paves the way for the industrialization of microporous polymer membranes from a theoretical perspective.

Porous Triptycene Network Based on Tröger's Base for CO2 Capture and Iodine Enrichment.

A three-dimensional rigid "six-connected" porous triptycene network based on Tröger's base (TB-PTN) was synthesized by using triptycenes as connectors and Tröger's base as linkers. With characteristics of a high surface area of 1528 m2 g-1, nitrogen-enriched groups, and superior thermal stability, TB-PTN displays a high CO2 uptake of 22.3 wt % (273 K, 1 bar) and excellent iodine vapor adsorption (240 wt %).

Triptycene-Fused Sterically Shielded Multi-Resonance TADF Emitter Enables High-Efficiency Deep Blue OLEDs with Reduced Dexter Energy Transfer.

Designing multi-resonance (MR) emitters that can simultaneously achieve narrowband emission and suppressed intermolecular interactions is challenging for realizing high color purity and stable blue organic light-emitting diodes (OLEDs). Herein, a sterically shielded yet extremely rigid emitter based on a triptycene-fused B,N core (Tp-DABNA) is proposed to address the issue. Tp-DABNA exhibits intense deep blue emissions with a narrow full width at half maximum (FWHM) and a high horizontal transition dipole ratio, superior to the well-known bulky emitter, t-DABNA. The rigid MR skeleton of Tp-DABNA suppresses structural relaxation in the excited state, with reduced contributions from the medium- and high-frequency vibrational modes to spectral broadening. The hyperfluorescence (HF) film composed of a sensitizer and Tp-DABNA shows reduced Dexter energy transfer compared to those of t-DABNA and DABNA-1. Notably, deep blue TADF-OLEDs with the Tp-DABNA emitter display higher external quantum efficiencies (EQEmax =24.8 %) and narrower FWHMs (≤26 nm) than t-DABNA-based OLEDs (EQEmax =19.8 %). The HF-OLEDs based on the Tp-DABNA emitter further demonstrate improved performance with an EQEmax of 28.7 % and mitigated efficiency roll-offs.

Construction of palladium porphyrins and triptycene photo-activated nanomaterial for enhanced colorimetric detection and inactivation of bacteria.

In the face of increasing bacterial resistance, design of high-performing and dual-functional nanomaterials to satisfy the requirements for both detecting and eradicating bacteria is of immense importance, but still remains a great challenge. Herein, a hierarchically three-dimensional (3D) porous organic frameworks (PdPPOPHBTT) was rationally designed and fabricated for the first time to realize ideal simultaneous detection and eradication of bacteria. PdPPOPHBTT covalently integrated palladium 5,10,15,20-tetrakis-(4'-bromophenyl) porphyrin (PdTBrPP, an excellent photosensitizer) with 2,3,6,7,12,13-hexabromotriptycene (HBTT, a 3D building module). The resulting material had outstanding NIR absorption, narrow bad gap and robust singlet oxygen (1O2) production capacity, which is responsible for the sensitive detection and effective removal of bacteria. We successfully realized the colorimetric detection of S. aureus and the efficient removal of S. aureus and E. coli. The first-principles calculations found at the highly activated 1O2 derived from the 3D conjugated periodic structures and ample palladium adsorption site in PdPPOPHBTT. The bacterial infection wound model revealed that PdPPOPHBTT possesses good disinfection ability and negligible side effect to normal tissue in vivo. This finding provides an innovative strategy for designing individual porous organic polymer (POPs) with multi-function and also broaden the applications of POPs as powerful nonantibiotic type of antimicrobials.

Intramolecular Hiyama Coupling: Synthesis of 1,8,13-Trisubstituted Chiral Triptycenes with Three Different Substituents by Intramolecular Substituent Transfer.

Herein, we describe Hiyama coupling via intramolecular substituent transfer from silicon on one blade of triptycenes to another to yield 1,8,13-trisubstituted chiral triptycenes. This reaction is attributed to the proximity effect of substituents on triptycene, which plays an important role in not only the formation of the oxy-palladacycle but also the activation of the silyl group to facilitate σ-bond metathesis. After bromination and nucleophilic ring opening, the second intramolecular Hiyama coupling provided various 1,8,13-trisubstituted chiral triptycenes. The optical resolution of 1,8,13-triptycene afforded an optically active form for the first time.

The heterometallic one-dimensional solvated coordination polymer [NiPt2Cl6(TRIP-Py)4]n.

The ditopic ligand 10-[4-(pyridin-4-yl)phenyl]-9-phospha-10-silatriptycene (TRIP-Py, C29H20NPSi) binds as a pyridine donor to NiII and as a phosphatriptycene donor towards PtII. The selectivity relies entirely on the Pearson character of the donor sites and the matching hardness of the respective metal cations. The product is the one-dimensional coordination polymer catena-poly[[[dichloridonickel(II)]-bis{µ-10-[4-(pyridin-4-yl)phenyl]-9-phospha-10-silatriptycene}-bis[dichloridoplatinum(II)]-bis{µ-10-[4-(pyridin-4-yl)phenyl]-9-phospha-10-silatriptycene}] dichloromethane pentasolvate ethanol icosasolvate], {[NiPt2Cl6(TRIP-Py)4]·5CH2Cl2·20EtOH}n (1), which retains large pores due to the inherent rigidity of the ligand. This is enabled by the caged triptycene scaffold which fixes the direction of the phosphorus donor with respect to the remaining molecule and especially the pyridyl moiety. In its crystal structure, which was determined from synchrotron data, the pores of the polymer are filled with dichloromethane and ethanol molecules. Finding a suitable model for the pore content is complicated as it is too disordered to give a reasonable atomic model but too ordered to be described by an electron gas solvent mask. This article presents an in-depth description of this polymer, as well as a discussion on the use of the bypass algorithm for solvent masks.

A Triptycene-Based 2D MOF with Vertically Extended Structure for Improving the Electrocatalytic Performance of CO2 to Methane.

Two-dimensional conductive metal-organic frameworks (2D-c-MOFs) have attracted extensive attention owing to their unique structures and physical-chemical properties. However, the planarly extended structure of 2D-c-MOFs usually limited the accessibility of the active sites. Herein, we designed a triptycene-based 2D vertically conductive MOF (2D-vc-MOF) by coordinating 2,3,6,7,14,15-hexahydroxyltriptycene (HHTC) with Cu2+ . The vertically extended 2D-vc-MOF(Cu) possesses a weak interlayer interaction, which leads to a facile exfoliation to the nanosheet. Compared with the classical 2D-c-MOFs with planarly extended 2D structures, 2D-vc-MOF(Cu) exhibits a 100 % increased catalytic activity in terms of turnover number and a two-fold increased selectivity. Density functional theory (DFT) calculations further revealed that higher activity originated from the lower energy barriers of the vertically extended 2D structures during the CO2 reduction reaction process.

Influence of Triptycene Annulation on the Photochromism of Diphenylnaphthopyrans: Entropic Control of Thermal Reversion.

Regioisomeric naphthopyrans annulated with triptycene, i. e., Prox-NP and Dist-NP, display divergent photochromic behaviors. While steady-state photolysis of Dist-NP led to a very labile colored intermediate that is not observable at room temperature, Prox-NP yielded a remarkably stable species characterized by X-ray crystallography as the TT isomer of o-quinonoid intermediate (Prox-NPQ) with t1/2 ca. 0.18 years at 298 K. The kinetic analysis of thermal reversion reveals that the bleaching of Prox-NPQ is entropically controlled; the steric effect due to the rigid triptycene scaffold renders Prox-NP a highly constrained system such that the photogenerated colored o-quinonoid form is more entropically relaxed. This constitutes the first instance of an entropically-controlled thermal reversion for the celebrated class of photochromic naphthopyrans. Based on the response of Prox-NP and its colored intermediate Prox-NPQ to different stimuli, namely, light, heat, and acid, the molecular system can be likened to a logic gate with the 'INHIBIT' function.